[woodb01]

Why do people continue to accept the ridiculous idea that evolution is anything but religious dogma? The "cute" little arguments offered by supporters of evolution simply DEFY common sense.

Unfortunately, when it comes to the subject of evolution, blind fanaticism override common sense and reason.

I just can't believe that order "magically" appears from disorder. The whole idea that a mess cleans itself up, and makes itself neat and orderly is completely beyond rational thinking... It shows how absurd the "scientific" arguments from evolutionists really is... Come on folks, stop and THINK about what evolution insists you believe!

[King Prout]

put your drinks down first.

[Izzy Dunne]

I just can't believe that order "magically" appears from disorder.

Please name a scientist who has asked you to believe that magic creates things.

[Izzy Dunne]

arguments offered by supporters of evolution simply DEFY common sense.

Common sense says that the sun revolves around the Earth.

[Moral Hazard]

This debate is so stupid. Creationists are like people arguing with Neil Armstrong after he got back from the moon that the Earth is actually flat.

[Manic_Episode]

Evolution: The ultimate in revisionist history.

[Ichneumon]

Why do people continue to accept the ridiculous idea that evolution is anything but religious dogma?

Because contrary to your ignorant and incorrect propaganda, there is a *MASSIVE* amount of evidence supporting evolution, it has passed tens of thousands of validation tests, and passed countless falsification tests.

Deal with it.

The "cute" little arguments offered by supporters of evolution simply DEFY common sense.

Endogenous retroviruses defy common sense? How?

Unfortunately, when it comes to the subject of evolution, blind fanaticism override common sense and reason.

And that's just the creationists, who want to blindly rail against evolution without actually being familiar with the evidence.

I just can't believe that order "magically" appears from disorder.

Neither can I. Magic has nothing to do with it. However, being well-versed in information science, and having studied the topic for over three decades, I'm well aware that information can and does arise naturally from "disorder" when certain natural processes are at work. Deal with it.

The whole idea that a mess cleans itself up, and makes itself neat and orderly is completely beyond rational thinking...

Translation: Because *YOU* can't understand how that can happen, it *must* be impossible...

Learn some science before you attempt to critique it.

[mikeus_maximus]

Anthony Flew, the guru of dogmatic atheism, was at least honest enough to follow the socratic path and go where the strongest evidence leads: Design by an intelligent mind.

Those with a more emotional objection to the evidence have an emotiobnal objection to overcome.

But they have to be able to see that self-created barrier first. And many simply won't.

[tallhappy]

The Golden Calf of Evolution is on Fire…

Does gold burn?

[Ichneumon]

[From: http://www.talkorigins.org/faqs/comdesc/]

29+ Evidences for Macroevolution

The Scientific Case for Common Descent

Version 2.85

Copyright © 1999-2004 by Douglas Theobald, Ph.D.

[Last Update: April 15, 2005]

Permission is granted to copy and print these pages in total for non-profit personal, educational, research, or critical purposes.

Introduction

volution, the overarching concept that unifies the biological sciences, in fact embraces a plurality of theories and hypotheses. In evolutionary debates one is apt to hear evolution roughly parceled between the terms "microevolution" and "macroevolution". Microevolution, or change beneath the species level, may be thought of as relatively small scale change in the functional and genetic constituencies of populations of organisms. That this occurs and has been observed is generally undisputed by critics of evolution. What is vigorously challenged, however, is macroevolution. Macroevolution is evolution on the "grand scale" resulting in the origin of higher taxa. In evolutionary theory it thus entails common ancestry, descent with modification, speciation, the genealogical relatedness of all life, transformation of species, and large scale functional and structural changes of populations through time, all at or above the species level (Freeman and Herron 2004; Futuyma 1998; Ridley 1993).

Common descent is a general descriptive theory that concerns the genetic origins of living organisms (though not the ultimate origin of life). The theory specifically postulates that all of the earth's known biota are genealogically related, much in the same way that siblings or cousins are related to one another. Thus, macroevolutionary history and processes necessarily entail the transformation of one species into another and, consequently, the origin of higher taxa. Because it is so well supported scientifically, common descent is often called the "fact of evolution" by biologists. For these reasons, proponents of special creation are especially hostile to the macroevolutionary foundation of the biological sciences.

This article directly addresses the scientific evidence in favor of common descent and macroevolution. This article is specifically intended for those who are scientifically minded but, for one reason or another, have come to believe that macroevolutionary theory explains little, makes few or no testable predictions, is unfalsifiable, or has not been scientifically demonstrated.

Outline

Introduction Universal Common Descent Defined Evidence for Common Descent is Independent of Mechanism What Counts as Scientific Evidence Other Explanations for the Biology How to Cite This Document Scientific Evidence and the Scientific Method Phylogenetics introduction Figure 1: A consensus universal phylogeny Cladistics and phylogenetic reconstruction Maximum parsimony Maximum likelihood Distance matrix methods Statistical support for phylogenies Does phylogenetic inference find correct trees? Caveats with determining phylogenetic trees	Part I. A unique, historical phylogenetic tree Unity of life Nested hierarchies Convergence of independent phylogenies Statistics of incongruent phylogenies Transitional forms Reptile-birds Reptile-mammals Ape-humans Legged whales Legged seacows Chronology of common ancestors	Part 2. Past history Anatomical vestiges Atavisms Whales with hindlimbs Humans tails Molecular vestiges Ontogeny and developmental biology Mammalian ear bones, reptilian jaws Pharyngeal pouches, branchial arches Snake embryos with legs Embryonic human tail Marsupial eggshell and caruncle Present biogeography Past biogeography Marsupials Horses Apes and humans
Part 3. Evolutionary opportunism Anatomical parahomology Molecular parahomology Anatomical convergence Molecular convergence Anatomical suboptimal function Molecular suboptimal function	Part 4. Molecular evidence Protein functional redundancy DNA functional redundancy Transposons Redundant pseudogenes Endogenous retroviruses	Part 5. Change Genetic Morphological Functional The strange past Stages of speciation Speciation events Morphological rates Genetic rates Closing remarks

[.cnI redruM]

>>>>>Contrary to popular myth, the theory of evolution has many holes.

So does most accepted science. An honest scientific thinker accepts the theory that has the fewest logical problems. Right now, I think ID still has it's share of holes. An intelligent design should be logical in the sense that it could be mapped and replicated once understood.

In other words, ID would quite literally imply that anyone who understood the design and had enough resources on hand, could, ipso facto, start playing God.

[Izzy Dunne]

and through a bunch of accidents, order is created

The old deck-of-cards analogy.
If you throw an unboxed, unordered deck of cards into the air, the odds are astronomically against them landing in order on the ground.
The odds are so great, that you might say they are a billion to one, maybe more.
Even if you do it a billion times, common sense says that "it won't happen".

"Therefore evolution didn't happen", is the conclusion.

Never mind that nobody has ever said that a microorganism will turn into a giraffe.
The deck-of-cards analogy fails because it assumes the same starting point each time.
Evolution says that you start from the BETTER of the original, or the mutation. The lesser dies out.
If you could put the cards back the way they were before you threw them, then you could choose to keep the new throw or the old throw, depending on whether it was more ordered or not.

[Ichneumon]

My rebuttal:

Background: Retroviruses reproduce by entering a cell of a host (like, say, a human), then embedding their own viral DNA into the cell's own DNA, which has the effect of adding a "recipe" for manufacturing more viruses to the cell's "instruction book". The cell then follows those instructions because it has no reason (or way) to "mistrust" the DNA instructions it contains. So the virus has converted the cell into a virus factory, and the new viruses leave the cell, and go find more cells to infect, etc.

However, every once in a while a virus's invasion plans don't function exactly as they should, and the virus's DNA (or portions of it) gets embedded into the cell's DNA in a "broken" manner. It's stuck into there, becoming part of the cell's DNA, but it's unable to produce new viruses. So there it remains, causing no harm. If this happens in a regular body cell, it just remains there for life as a "fossil" of the past infection and goes to the grave with the individual it's stuck in. All of us almost certainly contain countless such relics of the past viral infections we've fought off.

However... By chance this sometimes happens to a special cell in the body, a gametocyte cell that's one of the ones responsible for making sperm in males and egg cells in females, and if so subsequent sperm/eggs produced by that cell will contain copies of the "fossil" virus, since now it's just a portion of the entire DNA package of the cell. And once in a blue moon such a sperm or egg is lucky enough to be one of the few which participate in fertilization and are used to produce a child -- who will now inherit copies of the "fossilized" viral DNA in every cell of his/her body, since all are copied from the DNA of the original modified sperm/egg.

So now the "fossilized" viral DNA sequence will be passed on to *their* children, and their children's children, and so on. Through a process called neutral genetic drift, given enough time (it happens faster in smaller populations than large) the "fossil" viral DNA will either be flushed out of the population eventually, *or* by luck of the draw end up in every member of the population X generations down the road. It all depends on a roll of the genetic dice.

Due to the hurdles, "fossil" retroviral DNA strings (known by the technical name of "endogenous retroviruses") don't end up ubiquitous in a species very often, but it provably *does* happen. In fact, the Human DNA project has identified literally *thousands* of such fossilized "relics" of long-ago ancestral infections in the human DNA.

And several features of these DNA relics can be used to demonstrate common descent, including their *location*. The reason is that retroviruses aren't picky about where their DNA gets inserted into the host DNA. Even in an infection in a *single* individual, each infected cell has the retroviral DNA inserted into different locations than any other cell. Because the host DNA is so enormous (billions of basepairs in humans, for example), the odds of any retroviral insertion event matching the insertion location of any other insertion event are astronomically low. The only plausible mechanism by which two individuals could have retroviral DNA inserted into exactly the same location in their respective DNAs is if they inherited copies of that DNA from the same source -- a common ancestor.

Thus, shared endogenous retroviruses between, say, ape and man is almost irrefutable evidence that they descended from a common ancestor. *Unless* you want to suggest that they were created separately, and then a virus they were both susceptible to infected both a man and an ape in EXACTLY the same location in their DNAs (the odds of such a match by luck are literally on the order of 1,000,000,000,000,000,000 to 1...), *and* that the infections both happened in their gametocyte cells (combined odds on the order of 1,000,000 to 1) *and* that the one particular affected gametocyte is the one which produces the egg or sperm which is destined to produce an offspring (*HUGE* odds against), and *then* the resulting modified genome of the offspring becomes "fixed" in each respective population (1 out of population_size^squared)...

Then repeat that for *each* shared endogenous retrovirus (there are many) you'd like to claim was acquired independently and *not* from a shared ancestor...

Finally, you'd have to explain why, for say species A, B, and C, the pattern of shared same-location retroviruses is always *nested*, never *overlapped*. For example, all three will share some retroviruses, then A and B will both share several more, but if so then B *never* shares one with C that A doesn't also have (or at least remnants of).

In your "shared infection due to genetic similarities" suggestion, even leaving aside the near statistical impossibility of the infections leaving genetic "scars" in *exactly* the same locations in independent infections, one would expect to find cases of three species X, Y, and Z, where the degree of similarity was such that Y was "between" X and Z on some similarity scale, causing the same disease to befall X and Y but not Z, and another disease to affect Y and Z but not X. And yet, we don't find this in genetic markers. The markers are found in nested sequence, which is precisely what we would expect to see in cases of inheritance from common ancestry.

Here, for example, is an ancestry tree showing the pattern of shared same-location endogenous retroviruses of type HERV-K among primates:

This is just a partial list for illustration purposes -- there are many more.

Each labeled arrow on the chart shows an ERV shared in common by all the branches to the right, and *not* the branches that are "left-and-down". This is the pattern that common descent would make. And common descent is the *only* plausible explanation for it. Furthermore, similar findings tie together larger mammal groups into successively larger "superfamilies" of creatures all descended from a common ancestor.

Any presumption of independent acquisition is literally astronomically unlikely. And "God chose to put broken relics of viral infections that never actually happened into our DNA and line them up only in patterns that would provide incredibly strong evidence of common descent which hadn't actually happened" just strains credulity (not to mention would raise troubling questions about God's motives for such a misleading act).

Once again, the evidence for common descent -- as opposed to any other conceivable alternative explanation -- is clear and overwhelming.

Wait, want more? Endogenous retroviruses are just *one* type of genetic "tag" that makes perfect sense evolutionary and *no* sense under any other scenario. In addition to ERV's, there are also similar arguments for the patterns across species of Protein functional redundancies, DNA coding redundancies, shared Processed pseudogenes, shared Transposons (including *several* independent varieties, such as SINEs and LINEs), shared redundant pseudogenes, etc. etc. Here, for example, is a small map of shared SINE events among various mammal groups:

Like ERV's, any scenario which suggests that these shared DNA features were acquired separately strains the laws of probability beyond the breaking point, but they make perfect sense from an evolutionary common-descent scenario. In the above data, it is clear that the only logical conclusion is that, for example, the cetaceans, hippos, and ruminants shared a common ancestor, in which SINE events B and C entered its DNA and then was passed on to its descendants, yet this occurred after the point in time where an earlier common ancestor had given rise both to that species, and to the lineage which later became pigs.

And this pattern (giving the *same* results) is repeated over and over and over again when various kinds of molecular evidence from DNA is examined in detail.

The molecular evidence for evolution and common descent is overwhelming. The only alternative is for creationists to deny the obvious and say, "well maybe God decided to set up all DNA in *only* ways that were consistent with an evolutionary result even though He'd have a lot more options open to him, even including parts which by every measure are useless and exactly mimic copy errors, ancient infections, stutters, and other garbage inherited from nonexistent shared ancestors"...

Or how about:

Humans have 23 pairs of chromosomes ---chimps and gorillas have 24 pairs. How many pairs of chromosomes did the "common ancestor" have? Was it 23 or 24 pairs? How do you "evolve" missing or added chromosomes ---that would happen all at one time.

The common ancestor had 24 chromosomes.

If you look at the gene sequences, you'll find that Chromosome 2 in humans is pretty much just 2 shorter chimpanzee chromosomes pasted end-to-end, with perhaps a slight bit of lost overlap:

(H=Human, C=Chimpanzee, G=Gorilla, O=Orangutan)

Somewhere along the line, after humans split off from the other great apes, or during the split itself, there was an accidental fusion of two chromosomes, end-to-end. Where there used to be 24 chromosomes, now there were 23, but containing the same total genes, so other than a "repackaging", the DNA "instructions" remained the same.

If a chimpanzee gives birth to a creature with 23 chromosomes, that offspring isn't going to be a well-formed chimpanzee able to survive well.

It is if the same genes are present, which they would be in the case of a chromosome fusion.

Evolve would imply the genetic material changes little by little --not some big loss of two chromosomes at once but I don't see how they'd go away gene by gene.

Tacking two chromosomes together end-to-end is not a "big loss" of genes, and it really is a "little by little" change in the total genetic code. It's just been "regrouped" a bit. Instead of coming in 24 "packages", it's now contained in 23, but the contents are the same.

So how, you might ask, would the chromosomes from the first 23-chromosome "fused" individual match up with the 24 chromosomes from its mate when it tried to produce offspring? Very well, thanks for asking. The "top half" of the new extra-long Chromosome 2 would adhere to the original chromosome (call it "2p") from which it was formed, and likewise for the "bottom half" which would adhere to the other original shorter chromosome (call it "2q"). In the picture above, imagine the two chimp chromosomes sliding over to "match up" against the human chromosome. The chimp chromosomes would end up butting ends with each other, or slightly overlapping in a "kink", but chromosomes have overcome worse mismatches (just consider the XY pair in every human male -- the X and the Y chromosome are *very* different in shape, length, and structure, but they still pair up).

In fact, the "rubbing ends" of the matched-up chimp chromosomes, adhering to the double-long human-type chromosome, would be more likely to become fused together themselves.

For studies in which recent chromosome fusions have been discovered and found not to cause infertility, see:

Chromosomal heterozygosity and fertility in house mice (Mus musculus domesticus) from Northern Italy. Hauffe HC, Searle JB Department of Zoology, University of Oxford, Oxford OX1 3PS, United Kingdom. hauffe@novanet.it

An observed chromosome fusion: Hereditas 1998;129(2):177-80 A new centric fusion translocation in cattle: rob (13;19). Molteni L, De Giovanni-Macchi A, Succi G, Cremonesi F, Stacchezzini S, Di Meo GP, Iannuzzi L Institute of Animal Husbandry, Faculty of Agricultural Science, Milan, Italy.

J Reprod Fertil 1979 Nov;57(2):363-75 Cytogenetics and reproduction of sheep with multiple centric fusions (Robertsonian translocations). Bruere AN, Ellis PM

J Reprod Fertil Suppl 1975 Oct;(23):356-70 Cytogenetic studies of three equine hybrids. Chandley AC, Short RV, Allen WR.

In that last reference, the Przewalski horse, which has 33 chromosomes, and the domestic horse, with 32 chromosomes (due to a fusion), are able to mate and produce fertile offspring.

Meanwhile, the question may be asked, how do we know that the human Chromosome 2 is actually the result of a chromsome fusion at/since a common ancestor, and not simply a matter of "different design"?

Well, if two chromsomes accidentally merged, there should be molecular remnants of the original chromosomal structures (while a chromosome designed from scratch would have no need for such leftover "train-wreck" pieces).

Ends of chromosomes have characteristic DNA base-pair sequences called "telomeres". And there are indeed remnants of telomeres at the point of presumed fusion on human Chromosome 2 (i.e., where the two ancestral ape chromosomes merged end-to-end). If I may crib from a web page:

Telomeres in humans have been shown to consist of head to tail repeats of the bases 5'TTAGGG running toward the end of the chromosome. Furthermore, there is a characteristic pattern of the base pairs in what is called the pre-telomeric region, the region just before the telomere. When the vicinity of chromosome 2 where the fusion is expected to occur (based on comparison to chimp chromosomes 2p and 2q) is examined, we see first sequences that are characteristic of the pre-telomeric region, then a section of telomeric sequences, and then another section of pre-telomeric sequences. Furthermore, in the telomeric section, it is observed that there is a point where instead of being arranged head to tail, the telomeric repeats suddenly reverse direction - becoming (CCCTAA)3' instead of 5'(TTAGGG), and the second pre-telomeric section is also the reverse of the first telomeric section. This pattern is precisely as predicted by a telomere to telomere fusion of the chimpanzee (ancestor) 2p and 2q chromosomes, and in precisely the expected location. Note that the CCCTAA sequence is the reversed complement of TTAGGG (C pairs with G, and T pairs with A).

Another piece of evidence is that if human Chromosome 2 had formed by chromosome fusion in an ancestor instead of being designed "as is", it should have evidence of 2 centromeres (the "pinched waist" in the picture above -- chromosomes have centromeres to aid in cell division). A "designed" chromosome would need only 1 centromere. An accidentally "merged" chromosome would show evidence of the 2 centromeres from the two chromosomes it merged from (one from each). And indeed, as documented in (Avarello R, Pedicini A, Caiulo A, Zuffardi O, Fraccaro M, Evidence for an ancestral alphoid domain on the long arm of human chromosome 2. Hum Genet 1992 May;89(2):247-9), the functional centromere found on human Chromosome 2 lines up with the centromere of the chimp 2p chromosome, while there are non-functional remnants of the chimp 2q centromere at the expected location on the human chromosome.

As an aside, the next time some creationist claims that there is "no evidence" for common ancestry or evolution, keep in mind that the sort of detailed "detective story" discussed above is repeated literally COUNTLESS times in the ordinary pursuit of scientific research and examination of biological and other types of evidence. Common ancestry and evolution is confirmed in bit and little ways over and over and over again. It's not just something that a couple of whacky anti-religionists dream up out of thin air and promulgate for no reason, as the creationists would have you believe.

And:

[The poster known as Mr. LLLICHY wrote:] Here is that Vitamin C data

After discovering this same data on another thread along with more discussion than has appeared here (I've taken the liberty of pinging the participants of that discussion), I see what the "mystery" is supposed to be -- it's supposed be why did some sites have multiple mutations while (small) stretches of other sites had none? In other words, why do the mutations appear clustered?

(You know, it would really help if people explained their points and questions in more detail, instead of leaving people to guess what the poster was thinking...)

[LLLICHY wrote:] "U238" that decays thrice, pretty good trick when there is "U238" that does not decay at all in 50,000,000 years.

Actually, no site had mutations "thrice". Three different bases at a given site is only *two* mutations (one original base, plus two mutations from it to something else).

Here's the "mutation map" from the actual DNA data:

--1-12--1-1-1-1--------1112112--1---1-11-1--------1 ALL/n

No mutations ("-") in about half the sites, one mutation at several (17) sites, two mutations at three sites.

The first thing to keep in mind that random processes tend to "cluster" more than people expect anyway. People expect "randomness" to "spread out" somewhat evenly, but instead it's usually more "clumped", for statistical reasons that would be a diversion to go into right now. So "that looks uneven" isn't always a good indication that something truly is non-random.

If you don't believe me on that, I wrote a program which made 23 mutations totally at random on a 51-site sequence, then repeated the process to see what different random outcomes would look like:

10 X$=STRING$(51,"-")
20 FOR I=1 TO 23
30 J%=INT(RND*51)+1
40 C$=MID$(X$,J%,1)
50 IF C$="-" THEN MID$(X$,J%,1)="1" ELSE MID$(X$,J%,1)=CHR$(ASC(C$)+1)
60 NEXT I
70 PRINT X$
80 GOTO 10

Yeah, it's BASIC, so sue me. Here's a typical screenful of the results:

-21---1---2---111----2-----2-1121-------1---1--11-1
-1--1--21-11---1-1--1-1---1----1---21-11111---11---
3-11---3-----1-----11-2-1---1--1----3--2---1--1----
---1-1--22--1-1--2-2111--1-1111---1------1-------1-
---32----1-11-1-----1---2-231----1------1-----11--1
----2---21--1---4----1-------------11-1--111-11-211
11--1-1---1-----1--1------1----3111--1----111-2-1-2
1112---1-3-1----1-1-----1-1------121--111-------1-1
-111121--1----1----1-1-1-1-11-2---1-1-------1-111--
-----------11-1---11-11--------21----12211--1---131
--1-211-1-1----21--11-1-2----1--1----11---11-----11
12---1-13------------2---21-21---11-1-1-1--2-------
-----2-1---1-1----21--11-11-1---111-1--111-----2--1
-----1-----1-1-1-1---1-2----11-21-11--1-111---1-21-
---11--1-1-122-1-1-1--1-----2-1-1-1-------1-1---111
--2--11----2--1---12-2----1-1---1-1--1--12----1-1-1
-111-1-----1-1----------1-21111--1-2-11-11-1----11-
11-1--211-1221-----1--1-----11--1-2-1----------11--
-----1-12-11---2-1---11--1-2--1----11---111-1----11
11----1--12---12----1---31---1-11----2--1-11-1-----
---1--111-1--1-1-111----1-21----1-1-3---1------2--1
-2-11----1-1------1------2-1-1--111-111-1-1----1111
1--1--1-1---1-111111--2--1-1------112----2---11----

Notice how oddly "clustered" most of them look, including one run which left a 13-site stretch "absolutely untouched", contrary to intuition (while having *4* mutations at a single site!)

Frankly, I don't see anything in the real-life DNA mutation map which looks any different from these truly random runs. Random events tend to cluster more than people expect. That solves the "mystery" right there.

Also, there may be a selection factor -- the GLO gene is a *lot* bigger than this. One has to wonder if this small 51-bp section was presented just because it was the one that looked "least random". That would be a no-no, since one can always hand-select the most deviant subset out of larger sample in order to artificially skew the picture.

However, since there are some interesting evolutionary observations to be made, let's look at that DNA data again, slightly rearranged:

TAC CCC GTG GAG GTG CGC TTC ACT CGG GCG GAC GAC ATC CTG CTG AGC CCC  PIG
TAC CCC GTG GAG GTA CGC TTC ACT CGC GGG GAC GAC ATC CTG CTG AGC CCC  BOS

TAC CCC GTA GAG GTG CGC TTC ACC CGA GGC GAT GAC ATT CTG CTG AGC CCC  RAT
TAC CCC GTG GAG GTG CGC TTC ACC CGA GGT GAT GAC ATC CTG CTG AGC CCG  MOUSE

TAC CCT GTG GGG GTG CGC TTC ACC CGG GGG GAC GAC ATC CTG CTG AGC CCC  GUIN PIG

TAC CTG GTG GGG GTA CGC TTC ACC TGG AG* GAT GAC ATC CTA CTG AGC CCC  HUMAN
TAC CTG GTG GGG CTA CGC TTC ACC TGG AG* GAT GAC ATC CTA CTG AGC CCC  CHIMPANZEE
TAC CCG GTG GGG GTG CGC TTC ACC CAG AG* GAT GAC GTC CTA CTG AGC CCC  ORANGUTAN
TAA CCG GTG GGG GTG CGC TTC ACC CAA GG* GAT GAC ATC ATA CTG AGC CCC  MACAQUE

Here I've put spaces between codons, and clustered the closely-related species together: pig/cow as ungulates, rat/mouse for their obvious relationship, guinea pig right below them but separated because of the pseudogene nature of its GLO gene, then primates all in a group, with man's closest relative, the chimp, immediately below him, followed by the more distant orangutan, and the even more distant macaque. Also note that the top four have "working" GLO genes, and the bottom five have "broken" GLO pseudogenes.

First, let's consider just the four species with working GLO genes. Evolution predicts that even over large periods of time, these genes will be "highly conserved", with natural selection weeding out mutations that could "break" the gene. Note that the mutations will still have occurred in individuals of the population, but natural selection will "discourage" that mutation from spreading into the general population.

And before we go any further, let's talk about the "universal genetic code". In all mammals (indeed, in almost all living organisms), each triplet of DNA sites cause a particular amino acid to be formed. The mapping of triplets (called "codons") to amino acids is as follows:

Second Position of Codon

T

C

A

G

F
i
r
s
t

P
o
s
i
t
i
o
n

T

TTT	Phe	[F]
TTC	Phe	[F]
TTA	Leu	[L]
TTG	Leu	[L]

TCT	Ser	[S]
TCC	Ser	[S]
TCA	Ser	[S]
TCG	Ser	[S]

TAT	Tyr	[Y]
TAC	Tyr	[Y]
TAA	Ter	[end]
TAG	Ter	[end]

TGT	Cys	[C]
TGC	Cys	[C]
TGA	Ter	[end]
TGG	Trp	[W]

T

C

A

G

T
h
i
r
d

P
o
s
i
t
i
o
n

C

CTT	Leu	[L]
CTC	Leu	[L]
CTA	Leu	[L]
CTG	Leu	[L]

CCT	Pro	[P]
CCC	Pro	[P]
CCA	Pro	[P]
CCG	Pro	[P]

CAT	His	[H]
CAC	His	[H]
CAA	Gln	[Q]
CAG	Gln	[Q]

CGT	Arg	[R]
CGC	Arg	[R]
CGA	Arg	[R]
CGG	Arg	[R]

T

C

A

G

A

ATT	Ile	[I]
ATC	Ile	[I]
ATA	Ile	[I]
ATG	Met	[M]

ACT	Thr	[T]
ACC	Thr	[T]
ACA	Thr	[T]
ACG	Thr	[T]

AAT	Asn	[N]
AAC	Asn	[N]
AAA	Lys	[K]
AAG	Lys	[K]

AGT	Ser	[S]
AGC	Ser	[S]
AGA	Arg	[R]
AGG	Arg	[R]

T

C

A

G

G

GTT	Val	[V]
GTC	Val	[V]
GTA	Val	[V]
GTG	Val	[V]

GCT	Ala	[A]
GCC	Ala	[A]
GCA	Ala	[A]
GCG	Ala	[A]

GAT	Asp	[D]
GAC	Asp	[D]
GAA	Glu	[E]
GAG	Glu	[E]

GGT	Gly	[G]
GGC	Gly	[G]
GGA	Gly	[G]
GGG	Gly	[G]

T

C

A

G

(The above table imported from http://psyche.uthct.edu/shaun/SBlack/geneticd.html, which also has a nice introduction to the genetic code.)

Another version of the same table with nifty Java features and DNA database lookups can be found here.

The thing which is most relevant to the following discussion is the fact that most of the genetic codes are "redundant" -- more than one codon (triplet) encodes to exactly the same amino acid. This means that even in genes which are required for the organism, certain basepair mutations make absolutely no difference if the change is from one codon which maps into amino acid X to another codon which still maps into amino acid X. (This fact allows certain kinds of evolutionary "tracers" to be "read" from the DNA, as described here).

Now back to our DNA data. The redundancy in the genetic code means that some basepair sites will have more "degrees of freedom" than others (i.e., ways in which they can mutate without disrupting the gene's biological function in any way). Let's look at the four species with working GLO genes again:

TAC CCC GTG GAG GTG CGC TTC ACT CGG GCG GAC GAC ATC CTG CTG AGC CCC  PIG
TAC CCC GTG GAG GTA CGC TTC ACT CGC GGG GAC GAC ATC CTG CTG AGC CCC  BOS
TAC CCC GTA GAG GTG CGC TTC ACC CGA GGC GAT GAC ATT CTG CTG AGC CCC  RAT
TAC CCC GTG GAG GTG CGC TTC ACC CGA GGT GAT GAC ATC CTG CTG AGC CCG  MOUSE
  T   T   T   A   T A T   T   T A T   C   C   T   T T T T T   T   T
      A   A       A   A       A   C   A           A   A   A       A
      G   C       G   G       G   G   G               C   C       C
--- --- --1 --- --1 --- --- --1 --2 -12 --1 --- --1 --- --- --- --1

Under each site of the mouse DNA, I've listed the "alternative" bases which could be be substituted for the mouse base at that site WITHOUT ALTERING THE GENE'S FUNCTION (because of genetic code redundancy). And under that I show the "mutation map" of just those four species.

Note that most of the "alternative" bases are in the third base of each codon, *and* that this is where all but one of the mutations have appeared. This is because these were the sites which were "free" to mutate in the way they did, because the mutation was genetically neutral. That doesn't mean that the first and second sites of each codon were immune from mutation, it's just that when mutations did occur at those sites, natural selection weeded them out quickly because they most likely "broke" the GLO gene for the individuals which received that mutuation. What we see above is the results after natural selection has already "filtered" the undesirable mutations and left the ones which "do no harm".

Additionally, the two sites which have mutated twice (i.e. have a "2" in the mutation map) are ones which had more "allowable" mutations. Also note that the sites which had the fewest allowable alternatives (only one alternate letter allowed) didn't have any mutations fix at those sites, which is unsurprising since a "safe" mutation would be less likely to occur there versus a site that "allowed" two or three alternatives.

All this is as predicted by evolutionary theory, you'll note.

It also explains the one anomoly of the original mutation map, which is that the mutation counts do tend to be higher at the third base of a codon.

However... What about the one exception? The pig DNA has had one mutation at a site which does not encode to exactly the same amino acid (which is the case for *all* the other ones). In the pig DNA, the GGG codon (mapping to Glycine) has changed to a GCG codon (mapping to Alanine). What's up with that? Well, one of two things. First and most likely, just as base values in codons have a built-in redundancy, so do the amino acids which make up the proteins which result from the DNA templates. In other words, certain amino acids can be substituted for other ones at some sites in given proteins without making any functional difference. (This "protein functional redundancy" also has implications for "evolutionary tracer" analysis, see here.) That may well be the case for Alanine versus Glycine in the GLO protein, but I'm not enough of a biochemist to be able to say. The other option is that it *does* make some difference in the function of the pig GLO protein, but not enough to "break" the vitamin-C synthesis (as proven by the fact that pigs *can* synthesize vitamin C). So one way or another, it's not a deal-breaker even though pig GLO will not be 100% identical to cow/mouse/rat GLO. It's yet another "allowable" mutation.

More interesting evolutionary observations: The number of mutational differences between pig/cow is 3, the number between mouse/rat is 4, and the difference between rat/cow is 7 -- all roughly as one would expect from the evolutionary relatedness of these animals (cows/pigs and rats/mice are each closer to each other than the rodents are to the ungulates).

Now let's take a close look at the guinea pig:

TAC CCT GTG GGG GTG CGC TTC ACC CGG GGG GAC GAC ATC CTG CTG AGC CCC  GUIN PIG
--- --1 --- -1- --- --- --- --- --1 --1 --1 --- --- --- --- --- ---

The "mutation map" under the guinea pig DNA is compared to the mouse DNA. Fascinating: Note that four of the five mutations are in the third base of a codon, *and* are of the type "allowed" by the genetic code redundancy. This indicates strongly that most of the evolutionary divergence between guinea pigs and mice likely occurred while the guinea pig's ancestors still had a working GLO gene. This is the sort of prediction implied by the evolutionary theory which could be cross-checked by further research of various types, and if verified, would be yet further confirmation that evolutionary theory is likely correct. So far, evolutionary theory has been subjected to literally countless tests like this, large and small, and the vast majority of results have confirmed the evolutionary prediction. This track record is hard to explain if evolution is an invalid theory, as some assert...

Finally, let's look over the primate DNA and mutation map (relative to each other):

TAC CTG GTG GGG GTA CGC TTC ACC TGG AG* GAT GAC ATC CTA CTG AGC CCC  HUMAN
TAC CTG GTG GGG CTA CGC TTC ACC TGG AG* GAT GAC ATC CTA CTG AGC CCC  CHIMPANZEE
TAC CCG GTG GGG GTG CGC TTC ACC CAG AG* GAT GAC GTC CTA CTG AGC CCC  ORANGUTAN
TAA CCG GTG GGG GTG CGC TTC ACC CAA GG* GAT GAC ATC ATA CTG AGC CCC  MACAQUE
--1 -1- --- --- 1-1 --- --- --- 111 1-- --- --- 1-- 1-- --- --- ---

Evolutionary theory predicts that because the GLO gene is "broken" in primates (i.e. is a pseudogene), mutations in it are highly likely to be neutral (i.e., make no difference, since it can't get much more broken), and thus mutations are just as likely to accumulate at any site as any other. Is that what we see? Yup. There's no obvious pattern to the mutations between primates in the above mutation map, and unlike the pig/cow/mouse/rat mutation map, the mutations aren't predominantly at the "safer" third base of a codon, nor of a type that would be "safe". In fact, one base has vanished entirely, but no biggie, the gene's already broken.

Also, although primates share a more recent common ancestor than cows/pigs/mice/rats, note that they've already racked up almost as many relative mutations as the cow/pig/mouse/rat DNA. This too is just as evolutionary theory predicts, because many mutations in a functional gene (GLO in this case) will be "non-safe" and weeded out by natural selection, making for a slower mutation fixation rate overall than in a pseudogene (as GLO is in primates) where natural selection doesn't "care" about the vast majority of mutations since *most* are neutral. So pseudogenes accumulate mutations faster than functional genes (even though rate of mutation *occurence* in both are likely the same).

Finally, note that there are ZERO mutational differences between the human DNA and the chimpanzee DNA, our nearest living relative.

I also see some interesting implications in the DNA sequences concerning which specific mutation fixed during what branch of the common-descent evolutionary tree for all the species represented, but reconstructing that would not only take another couple hours, at least, but would be a major bear to code in HTML, since I'd have to draw trees with annotations on the nodes... Bleugh.

In any case, I hope I've clarified some of the methods by which biologists find countless confirmations of evolution in DNA data. This is just a "baby" example, and to be more statistically valid would have to be done over much vaster sections of DNA sequences, but my intent was to demonstrate some of the concepts.

And if such a small amount of DNA as this can make small confirmations of evolutionary predictions, imagine the amount of confirmation from billion-basepair DNA data from each species compared across thousands of species... The amount of confirmatory discoveries for evolution from DNA analysis has already been vast, and promises to only grow in the future. For an overview of some of the different lines of evidence being studied, see The Journal of Molecular Evolution -- abstracts of all articles, current and back issues, can be browsed free online.

Theropod dinosaur to bird evolutionary transition:

The cladogram for the evolution of flight looks like this:

(Note -- each name along the top is a known transitional fossil; and those aren't all that have been discovered.) Here's a more detailed look at the middle section:

Fossils discovered in the past ten years in China have answered most of the "which came first" questions about the evolution of birds from dinosaurs.

We now know that downy feathers came first, as seen in this fossil of Sinosauropteryx:

That's a close-up of downy plumage along the backbone. Here's a shot of an entire fossil

Sinosauropteryx was reptilian in every way, not counting the feathers. It had short forelimbs, and the feathers were all the same size. Presumably, the downy feathers evolved from scales driven by a need for bodily insulation.

Next came Protarchaeopteryx:

It had long arms, broad "hands", and long claws:

Apparently this species was driven by selection to develop more efficient limbs for grasping prey. One of the interesting things about this species is that the structure of the forelimb has been refined to be quite efficient at sweeping out quickly to grab prey, snap the hands together, then draw them back towards the body (mouth?). The specific structures in question are the semilunate carpal (a wrist bone), that moves with the hand in a broad, flat, 190 degree arc, heavy chest muscles, bones of the arm which link together with the wrist so as to force the grasping hands to spread out toward the prey during the forestroke and fold in on the prey during the upstroke. Not only is this a marvelously efficient prey-grabbing mechanism, but the same mechanism is at the root of the wing flight-stroke of modern birds. Evolution often ends up developing a structure to serve one need, then finds it suitable for adaptation to another. Here, a prey-grasping motion similar in concept to the strike of a praying mantis in a reptile becomes suitable for modifying into a flapping flight motion.

Additionally, the feathers on the hands and tail have elongated, becoming better suited for helping to sweep prey into the hands.

Next is Caudipteryx:

This species had hand and tail feathers even more developed than the previous species, and longer feathers, more like that of modern birds:

However, it is clear that this was still not a free-flying animal yet, because the forelimbs were too short and the feathers not long enough to support its weight, and the feathers were symmetrical (equal sized "fins" on each side of the central quill). It also had very reduced teeth compared to earlier specimens and a stubby beak:

But the elongation of the feathers indicates some aerodynamic purpose, presumably gliding after leaping (or falling) from trees which it had climbed with its clawed limbs, in the manner of a flying squirrel. Feathers which were developed "for" heat retention and then pressed into service to help scoop prey were now "found" to be useful for breaking falls or gliding to cover distance (or swooping down on prey?).

Next is Sinornithosaurus:

Similar to the preceding species, except that the pubis bone has now shifted to point to the back instead of the front, a key feature in modern birds (when compared to the forward-facing publis bone in reptiles). Here are some of the forearm feathers in detail:

Long feathers in detail:

Artists' reconstruction:

Next is Archaeopteryx:

The transition to flight is now well underway. Archaeopteryx has the reversed hallux (thumb) characteristic of modern birds, and fully developed feathers of the type used for flight (long, aligned with each other, and assymetrical indicating that the feathers have been refined to function aerodynamically). The feathers and limbs are easily long enough to support the weight of this species in flight. However, it lacks some structures which would make endurance flying more practical (such as a keeled sternum for efficient anchoring of the pectoral muscles which power the downstroke) and fused chest vertebrae. Archaeopteryx also retains a number of clearly reptilian features still, including a clawed "hand" emerging from the wings, small reptilian teeth, and a long bony tail. After the previous species' gliding abilities gave it an advantage, evolution would have strongly selected for more improvements in "flying" ability, pushing the species towards something more resembling sustained powered flight.

Next is Confuciusornis:

This species had a nearly modern flight apparatus. It also displays transitional traits between a reptilian grasping "hand" and a fully formed wing as in modern birds -- the outer two digits (the earlier species had three-fingered "hands") in Confuciusornis are still free, but the center digit has now formed flat, broad bones as seen in the wings of modern birds.

Additionally, the foot is now well on its way towards being a perching foot as in modern birds:

It also has a keeled sternum better suited for long flight, and a reduced number of vertebrae in the tail, on its way towards becoming the truncated tail of modern birds (which while prominent, is a small flap of muscle made to look large only because of the long feathers attached).

From this species it's only a small number of minor changes to finish the transition into the modern bird family.

(Hey, who said there are no transitional fossils? Oh, right, a lot of dishonest creationists. And there are a lot more than this, I've just posted some of the more significant milestones.)

There's been a very recent fossil find along this same lineage, too new for me to have found any online images to include in this article. And analysis is still underway to determine exactly where it fits into the above lineage. But it has well-formed feathers, which extend out from both the "arms" and the legs. Although it wasn't advanced enough to fully fly, the balanced feathering on the front and back would have made it ideally suited for gliding like a flying squirrel, and it may be another link between the stage where feathers had not yet been pressed into service as aerodynamic aids, and the time when they began to be used more and more to catch the air and developing towards a "forelimbs as wings" specialization.

So in short, to answer your question about how flight could have developed in birds, the progression is most likely some minor refinement on the following:

1. Scales modified into downy feathers for heat retention.
2. Downy feathers modified into "straight" feathers for better heat retention (modern birds still use their body "contour feathers" in this fashion).
3. Straight feathers modified into a "grasping basket" on the hands (with an accompanying increase in reach for the same purpose).
4. Long limbs with long feathers refined to better survive falls to the ground.
5. "Parachute" feathers refined for better control, leading to gliding.
6. Gliding refined into better controlled, longer gliding.
7. Long gliding refined into short powered "hops".
8. Short powered flight refined into longer powered flight.
9. Longer powered flight refined into long-distance flying.

Note that in each stage, the current configuration has already set the stage for natural selection to "prefer" individuals which better meet the requirements of the next stage. Evolution most often works like this; by taking some pre-existing ability or structure, and finding a better use for it or a better way to make it perform its current use.

Whale Evolution

The transitional fossils in the evolutionary origin of whales is especially striking. The following is an excerpt from The Origin of Whales and the Power of Independent Evidence . This excerpt is excellent all by itself, but one should really read the entire essay in order to get the "big picture" of whale evolution:

The evidence
The evidence that whales descended from terrestrial mammals is here divided into nine independent parts: paleontological, morphological, molecular biological, vestigial, embryological, geochemical, paleoenvironmental, paleobiogeographical, and chronological. Although my summary of the evidence is not exhaustive, it shows that the current view of whale evolution is supported by scientific research in several distinct disciplines.

1. Paleontological evidence
The paleontological evidence comes from studying the fossil sequence from terrestrial mammals through more and more whale-like forms until the appearance of modern whales. Although the early whales (Archaeocetes) exhibit greater diversity than I have space to discuss here, the examples in this section represent the trends that we see in this taxon. Although there are two modern suborders of whales (Odontocetes and Mysticetes), this discussion will focus on the origin of the whales as an order of mammals, and set aside the issues related to the diversification into suborders.

Sinonyx
We start with Sinonyx, a wolf-sized mesonychid (a primitive ungulate from the order Condylarthra, which gave rise to artiodactyls, perissodactyls, proboscideans, and so on) from the late Paleocene, about 60 million years ago. The characters that link Sinonyx to the whales, thus indicating that they are relatives, include an elongated muzzle, an enlarged jugular foramen, and a short basicranium (Zhou and others 1995). The tooth count was the primitive mammalian number (44); the teeth were differentiated as are the heterodont teeth of today's mammals. The molars were very narrow shearing teeth, especially in the lower jaw, but possessed multiple cusps. The elongation of the muzzle is often associated with hunting fish - all fish-hunting whales, as well as dolphins, have elongated muzzles. These features were atypical of mesonychids, indicating that Sinonyx was already developing the adaptations that later became the basis of the whales' specialized way of life.

Pakicetus
The next fossil in the sequence, Pakicetus, is the oldest cetacean, and the first known archaeocete. It is from the early Eocene of Pakistan, about 52 million years ago (Gingerich and others 1983). Although it is known only from fragmentary skull remains, those remains are very diagnostic, and they are definitely intermediate between Sinonyxand later whales. This is especially the case for the teeth. The upper and lower molars, which have multiple cusps, are still similar to those of Sinonyx, but the premolars have become simple triangular teeth composed of a single cusp serrated on its front and back edges. The teeth of later whales show even more simplification into simple serrated triangles, like those of carnivorous sharks, indicating that Pakicetus's teeth were adapted to hunting fish.
Gingrich and others (1983) published this reconstruction of the skull of
Pakicetus inachus (redrawn for RNCSE by Janet Dreyer).

A well-preserved cranium shows that Pakicetus was definitely a cetacean with a narrow braincase, a high, narrow sagittal crest, and prominent lambdoidal crests. Gingerich and others (1983) reconstructed a composite skull that was about 35 centimeters long. Pakicetus did not hear well underwater. Its skull had neither dense tympanic bullae nor sinuses isolating the left auditory area from the right one - an adaptation of later whales that allows directional hearing under water and prevents transmission of sounds through the skull (Gingerich and others 1983). All living whales have foam-filled sinuses along with dense tympanic bullae that create an impedance contrast so they can separate sounds arriving from different directions. There is also no evidence in Pakicetus of vascularization of the middle ear, which is necessary to regulate the pressure within the middle ear during diving (Gingerich and others 1983). Therefore, Pakicetus was probably incapable of achieving dives of any significant depth. This paleontological assessment of the ecological niche of Pakicetus is entirely consistent with the geochemical and paleoenvironmental evidence. When it came to hearing, Pakicetus was more terrestrial than aquatic, but the shape of its skull was definitely cetacean, and its teeth were between the ancestral and modern states.


Zhou and others (1995) published this reconstruction of the skull of
Sinonyx jiashanensis (redrawn for RNCSE by Janet Dreyer).

Ambulocetus
In the same area that Pakicetus was found, but in sediments about 120 meters higher, Thewissen and colleagues (1994) discovered Ambulocetus natans, "the walking whale that swims", in 1992. Dating from the early to middle Eocene, about 50 million years ago, Ambulocetus is a truly amazing fossil. It was clearly a cetacean, but it also had functional legs and a skeleton that still allowed some degree of terrestrial walking. The conclusion that Ambulocetus could walk by using the hind limbs is supported by its having a large, stout femur. However, because the femur did not have the requisite large attachment points for walking muscles, it could not have been a very efficient walker. Probably it could walk only in the way that modern sea lions can walk - by rotating the hind feet forward and waddling along the ground with the assistance of their forefeet and spinal flexion. When walking, its huge front feet must have pointed laterally to a fair degree since, if they had pointed forward, they would have interfered with each other.

The forelimbs were also intermediate in both structure and function. The ulna and the radius were strong and capable of carrying the weight of the animal on land. The strong elbow was strong but it was inclined rearward, making possible rearward thrusts of the forearm for swimming. However, the wrists, unlike those of modern whales, were flexible.

It is obvious from the anatomy of the spinal column that Ambulocetus must have swum with its spine swaying up and down, propelled by its back feet, oriented to the rear. As with other aquatic mammals using this method of swimming, the back feet were quite large. Unusually, the toes of the back feet terminated in hooves, thus advertising the ungulate ancestry of the animal. The only tail vertebra found is long, making it likely that the tail was also long. The cervical vertebrae were relatively long, compared to those of modern whales; Ambulocetus must have had a flexible neck.



Ambulocetus's skull was quite cetacean (Novacek 1994). It had a long muzzle, teeth that were very similar to later archaeocetes, a reduced zygomatic arch, and a tympanic bulla (which supports the eardrum) that was poorly attached to the skull. Although Ambulocetus apparently lacked a blowhole, the other skull features qualify Ambulocetus as a cetacean. The post-cranial features are clearly in transitional adaptation to the aquatic environment. Thus Ambulocetus is best described as an amphibious, sea-lion-sized fish-eater that was not yet totally disconnected from the terrestrial life of its ancestors.

Rodhocetus
In the middle Eocene (46-7 million years ago) Rodhocetus took all of these changes even further, yet still retained a number of primitive terrestrial features (Gingerich and others 1994). It is the earliest archaeocete of which all of the thoracic, lumbar, and sacral vertebrae have been preserved. The lumbar vertebrae had higher neural spines than in earlier whales. The size of these extensions on the top of the vertebrae where muscles are attached indicate that Rodhocetus had developed a powerful tail for swimming.


Gingrich and others (1994) published this reconstruction of the skeleton of
Rodhocetus kasrani (redrawn for RNCSE by Janet Dreyer).

Elsewhere along the spine, the four large sacral vertebrae were unfused. This gave the spine more flexibility and allowed a more powerful thrust while swimming. It is also likely that Rodhocetus had a tail fluke, although such a feature is not preserved in the known fossils: it possessed features - shortened cervical vertebrae, heavy and robust proximal tail vertebrae, and large dorsal spines on the lumbar vertebrae for large tail and other axial muscle attachments - that are associated in modern whales with the development and use of tail flukes. All in all, Rodhocetus must have been a very good tail-swimmer, and it is the earliest fossil whale committed to this manner of swimming.

The pelvis of Rodhocetus was smaller than that of its predecessors, but it was still connected to the sacral vertebrae, meaning that Rodhocetus could still walk on land to some degree. However, the ilium of the pelvis was short compared to that of the mesonychids, making for a less powerful muscular thrust from the hip during walking, and the femur was about 1/3 shorter than Ambulocetus’s, so Rodhocetus probably could not get around as well on land as its predecessors (Gingerich and others 1994).

Rodhocetus's skull was rather large compared to the rest of the skeleton. The premaxillae and dentaries had extended forward even more than its predecessors’, elongating the skull and making it even more cetacean. The molars have higher crowns than in earlier whales and are greatly simplified. The lower molars are higher than they are wide. There is a reduced differentiation among the teeth. For the first time, the nostrils have moved back along the snout and are located above the canine teeth, showing blowhole evolution. The auditory bullae are large and made of dense bone (characteristics unique to cetaceans), but they apparently did not contain the sinuses typical of later whales, making it questionable whether Rodhocetus possessed directional hearing underwater.

Overall, Rodhocetus showed improvements over earlier whales by virtue of its deep, slim thorax, longer head, greater vertebral flexibility, and expanded tail-related musculature. The increase in flexibility and strength in the back and tail with the accompanying decrease in the strength and size of the limbs indicated that it was a good tail-swimmer with a reduced ability to walk on land.

Basilosaurus
The particularly well-known fossil whale Basilosaurus represents the next evolutionary grade in whale evolution (Gingerich 1994). It lived during the late Eocene and latest part of the middle Eocene (35-45 million years ago). Basilosaurus was a long, thin, serpentine animal that was originally thought to have been the remains of a sea serpent (hence it is name, which actually means "king lizard"). Its extreme body length (about 15 meters) appears to be due to a feature unique among whales; its 67 vertebrae are so long compared to other whales of the time and to modern whales that it probably represents a specialization that sets it apart from the lineage that gave rise to modern whales.

What makes Basilosaurus a particularly interesting whale, however, is the distinctive anatomy of its hind limbs (Gingerich and others 1990). It had a nearly complete pelvic girdle and set of hindlimb bones. The limbs were too small for effective propulsion, less than 60 cm long on this 15-meter-long animal, and the pelvic girdle was completely isolated from the spine so that weight-bearing was impossible. Reconstructions of the animal have placed its legs external to the body - a configuration that would represent an important intermediate form in whale evolution.

Although no tail fluke has ever been found (since tail flukes contain no bones and are unlikely to fossilize), Gingerich and others (1990) noted that Basilosaurus's vertebral column shares characteristics of whales that do have tail flukes. The tail and cervical vertebrae are shorter than those of the thoracic and lumbar regions, and Gingerich and others (1990) take these vertebral proportions as evidence that Basilosaurus probably also had a tail fluke.

Further evidence that Basilosaurus spent most of its time in the water comes from another important change in the skull. This animal had a large single nostril that had migrated a short distance back to a point corresponding to the back third of the dental array. The movement from the forward extreme of the snout to the a position nearer the top of the head is characteristic of only those mammals that live in marine or aquatic environments.

Dorudon
Dorudon was a contemporary of Basilosaurus in the late Eocene (about 40 million years ago) and probably represents the group most likely to be ancestral to modern whales (Gingerich 1994). Dorudon lacked the elongated vertebrae of Basilosaurus and was much smaller (about 4-5 meters in length). Dorudon’s dentition was similar to Basilosaurus’s; its cranium, compared to the skulls of Basilosaurus and the previous whales, was somewhat vaulted (Kellogg 1936). Dorudon also did not yet have the skull anatomy that indicates the presence of the apparatus necessary for echolocation (Barnes 1984).


Gingrich and Uhen (1996) published this reconstruction of the skeleton of
Dorudon atrox (redrawn for RNCSE by Janet Dreyer).



Basilosaurus and Dorudon were fully aquatic whales (like Basilosaurus, Dorudon had very small hind limbs that may have projected slightly beyond the body wall). They were no longer tied to the land; in fact, they would not have been able to move around on land at all. Their size and their lack of limbs that could support their weight made them obligate aquatic mammals, a trend that is elaborated and reinforced by subsequent whale taxa.

Clearly, even if we look only at the paleontological evidence, the creationist claim of "No fossil intermediates!" is wrong. In fact, in the case of whales, we have several, beautifully arranged in morphological and chronological order.

In summarizing the paleontological evidence, we have noted the consistent changes that indicate a series of adaptations from more terrestrial to more aquatic environments as we move from the most ancestral to the most recent species. These changes affect the shape of the skull, the shape of the teeth, the position of the nostrils, the size and structure of both the forelimbs and the hindlimbs, the size and shape of the tail, and the structure of the middle ear as it relates to directional hearing underwater and diving. The paleontological evidence records a history of increasing adaptation to life in the water - not just to any way of life in the water, but to life as lived by contemporary whales.

The paleontological (i.e. fossil) evidence for evolutionary transitions is overwhelming to anyone who has actually examined the evidence with an open mind. However, a stubborn person attempting to deny the obvious can rationalize it away by refusing to see the clear sequences of morphological change, and insisting that one can't "prove" that the various fossil specimens are "really" necessarily related. That excuse crumbles when one compares the fossil evidence to the *many* other independent lines of evidence which confirm the fossil evidence. For example, concerning whale evolution:

Evolution of whales from terrestrial mammals

Links on whale evolution

(From Plagiarized Errors and Molecular Genetics)

.

A particularly impressive example of shared retroposons has recently been reported linking cetaceans (whales, dolphins and porpoises) to ruminants and hippopotamuses, and it is instructive to consider this example in some detail. Cetaceans are sea-living animals that bear important similarities to land-living mammals; in particular, the females have mammary glands and nurse their young. Scientists studying mammalian anatomy and physiology have demonstrated greatest similarities between cetaceans and the mammalian group known as artiodactyls (even-toed ungulates) including cows, sheep, camels and pigs. These observations have led to the evolutionist view that whales evolved from a four-legged artiodactyl ancestor that lived on land. Creationists have capitalized on the obvious differences between the familiar artiodactyls and whales, and have ridiculed the idea that whales could have had four-legged land-living ancestors. Creationists who claim that cetaceans did not arise from four-legged land mammals must ignore or somehow dismiss the fossil evidence of apparent whale ancestors looking exactly like one would predict for transitional species between land mammals and whales--with diminutive legs and with ear structures intermediate between those of modern artiodactyls and cetaceans (Nature 368:844,1994; Science 263: 210, 1994). (A discussion of fossil ancestral whale species with references may be found at http://www.talkorigins.org/faqs/faq-transitional/part2b.html#ceta) Creationists must also ignore or dismiss the evidence showing the great similarity between cetacean and artiodactyl gene sequences (Molecular Biology & Evolution 11:357, 1994; ibid 13: 954, 1996; Gatesy et al, Systematic Biology 48:6, 1999).

Recently retroposon evidence has solidified the evolutionary relationship between whales and artiodactyls. Shimamura et al. (Nature 388:666, 1997; Mol Biol Evol 16: 1046, 1999; see also Lum et al., Mol Biol Evol 17:1417, 2000; Nikaido and Okada, Mamm Genome 11:1123, 2000) studied SINE sequences that are highly reduplicated in the DNA of all cetacean species examined. These SINES were also found to be present in the DNA of ruminants (including cows and sheep) but not in DNA of camels and pigs or more distantly related mammals such as horse, elephant, cat, human or kangaroo. These SINES apparently originated in a specific branch of ancestral artiodactyls after this branch diverged from camels, pigs and other mammals, but before the divergence of the lines leading to modern cetaceans, hippopotamus and ruminants. (See Figure 5.) In support of this scenario, Shimamura et al. identified two specific insertions of these SINES in whale DNA (insertions B and C in Figure 5) and showed that in DNA of hippopotamus, cow and sheep these same two sites contained the SINES; but in camel and pig DNA the same sites were "empty" of insertions. More recently, hippopotamus has been identified as the closest living terrestrial relative of cetaceans since hippos and whales share retroposon insertions (illustrated by D and E in Figure 5) that are not found in any other artiodactyls (Nikaido et al, PNAS 96:10261, 1999). The close hippo-whale relationship is consistent with previously reported sequence similarity comparisons (Gatesy, Mol Biol Evol 14:537, 1997) and with recent fossil finds (Gingerich et al., Science 293:2239, 2001; Thewissen et al., Nature 413:277, 2001) that resolve earlier paleontological conflicts with the close whale-hippo relationship. (Some readers have wondered: if ruminants are more closely related to whales than to pigs and camels, why are ruminants anatomically more similar to pigs and camels than they are to whales? Apparently this results from the fact that ruminants, pigs and camels changed relatively little since their last common ancestor, while the cetacean lineage changed dramatically in adapting to an aquatic lifestyle, thereby obliterating many of the features -- like hooves, fur and hind legs -- that are shared between its close ruminant relatives and the more distantly related pigs and camels. This scenario illustrates the fact that the rapid evolutionary development of adaptations to a new niche can occur through key functional mutations, leaving the bulk of the DNA relatively unchanged. The particularly close relationship between whales and hippos is consistent with several shared adaptations to aquatic life, including use of underwater vocalizations for communication and the absence of hair and sebaceous glands.) Thus, retroposon evidence strongly supports the derivation of whales from a common ancestor of hippopotamus and ruminants, consistent with the evolutionary interpretation of fossils and overall DNA sequence similarities. Indeed, the logic of the evidence from shared SINEs is so powerful that SINEs may be the best available characters for deducing species relatedness (Shedlock and Okada, Bioessays 22:148, 2000), even if they are not perfect (Myamoto, Curr. Biology 9:R816, 1999).

Figure 5. Specific SINE insertions can act as "tracers" that illuminate phylogenetic relationships. This figure summarizes some of the data on SINEs found in living artiodactyls and shows how the shared insertions can be interpreted in relation to evolutionary branching. A specific SINE insertion event ("A" in the Figure) apparently occurred in a primitive common ancestor of pigs, ruminants, hippopotamus and cetaceans, since this insertion is present in these modern descendants of that common ancestor; but it is absent in camels, which split off from the other species before this SINE inserted. More recent insertions B and C are present only in ruminants, hippopotamus and cetaceans. Insertions D and E are shared only by hippopotamus and cetaceans, thereby identifying hippopotamus as the closest living relative of cetaceans (at least among the species examined in these studies). SINE insertions F and G occurred in the ruminant lineage after it diverged from the other species; and insertions H and I occurred after divergence of the cetacean lineage.

That's just a quick layman-level overview of *one* of the many ways that whale evolution has been verified. For more technical examinations along several independent lines of evidence, see for example:

SINE Evolution, Missing Data, and the Origin of Whales

Phylogenetic relationships among cetartiodactyls based on insertions of short and long interpersed elements: Hippopotamuses are the closest extant relatives of whales

Evidence from Milk Casein Genes that Cetaceans are Close Relatives of Hippopotamid Artiodactyls

Analyses of mitochondrial genomes strongly support a hippopotamus±whale clade

A new, diminutive Eocene whale from Kachchh (Gujarat, India) and its implications for locomotor evolution of cetaceans

A new Eocene archaeocete (Mammalia, Cetacea) from India and the time of origin of whales

Mysticete (Baleen Whale) Relationships Based upon the Sequence of the Common Cetacean DNA Satellite1

The Mitochondrial Genome of the Sperm Whale and a New Molecular Reference for Estimating Eutherian Divergence Dates

Limbs in whales and limblessness in other vertebrates: mechanisms of evolutionary and developmental transformation and loss

Eocene evolution of whale hearing

Novel Phylogeny of Whales Revisited but Not Revised

Land-to-sea transition in early whales: evolution of Eocene Archaeoceti (Cetacea) in relation to skeletal proportions and locomotion of living semiaquatic mammals

Subordinal artiodactyl relationships in the light of phylogenetic analysis of 12 mitochondrial protein-coding genes

New Morphological Evidence for the Phylogeny of Artiodactyla, Cetacea, and Mesonychidae

Cetacean Systematics

LIKELIHOOD ESTIMATION OF THE TIME OF ORIGIN OF CETACEA AND THE TIME OF DIVERGENCE OF CETACEA AND ARTIODACTYLA

Phylogenetic Relationships of Artiodactyls and Cetaceans as Deduced from the Comparison of Cytochrome b and 12s rRNA Mitochondrial Sequences

Molecular evolution of mammalian ribonucleases

And much, much more.

[Ichneumon]

When the details of various biological mechanisms are examined, coherent evolutionary histories are discovered for them, again consistent with the predictions of evolutionary theory. For example, here are discoveries about the origins of the vertebrate clotting mechanism -- all consistent with the predictions of evolution:

Evolution of the vertebrate clotting mechanism

In detail, discuss why gradual evolution of blood clotting with 10 protein feedback loops all working at once is actually quite feasible evolutionarily speaking.

Well, okay, since you insist... Check out The Evolution of Vertebrate Blood Clotting, or The evolution of vertebrate blood coagulation as viewed from a comparison of puffer fish and sea squirt genomes. Excerpt from the latter paper:

It is thought that 50–100 million years separate the appearances of urochordates (which include the sea squirt) and vertebrates. During that time the machinery for thrombin-catalyzed fibrin formation had to be concocted by gene duplication and the shuffling about of key modular domains. The relative times of duplicative events can be estimated by various means, the most obvious being the presence or absence of a gene in earlier diverging organisms, although it must be kept in mind that lineages may lose genes. Another way to gauge events is from the relative positions of various gene products on phylogenetic trees, earlier branching implying earlier appearance. In this regard, (pro)thrombin invariably appears lower on the phylogenetic trees than do the other vitamin K-dependent factors (Fig. 2).

The order of events can also be inferred by considering the most parsimonious route to assembling the various clusters of peripheral domains. Nine of the proteases under discussion can be accounted for by six domain-swapping events (Fig. 5). Indeed, the presence of a multiple-kringle protease in the sea squirt genome provides a reasonable model for a step-by-step parallel evolution of the clotting and lysis systems. It should be noted that a serine protease with only one kringle has been found in the ascidian Herdmania momus (36). Although numerous scenarios have been offered in the past about how modular exchange was involved in generating these schemes (refs. 4, 12, and 37–41, inter alia), the new genomic data now provide a realistic set of starting materials.

Also, Evolution of enzyme cascades from embryonic development to blood coagulation:

Recent delineation of the serine protease cascade controlling dorsal-ventral patterning during Drosophila embryogenesis allows this cascade to be compared with those controlling clotting and complement in vertebrates and invertebrates. The identification of discrete markers of serine protease evolution has made it possible to reconstruct the probable chronology of enzyme evolution and to gain new insights into functional linkages among the cascades. Here, it is proposed that a single ancestral developmental/immunity cascade gave rise to the protostome and deuterostome developmental, clotting and complement cascades. Extensive similarities suggest that these cascades were built by adding enzymes from the bottom of the cascade up and from similar macromolecular building blocks.

That was the abstract. An excerpt from the text:

The downstream protease of the vertebrate clotting cascade (Fig. 1d), thrombin, belongs to the same lineage as complement factors C1r and C1s. The upstream and middle proteases of the clotting cascade (factors VII, IX and X) belong to the most modern lineage, that of horseshoe crab clotting factor C. Therefore, the lineage of thrombin is parental to that of the upstream and middle proteases of the clotting cascade (Table 1) and distinguishes it from the other vitamin-K-dependent clotting proteases (factors VII, IX and X, and protein C). This conclusion agrees with sequence and species comparisons implying that thrombin was the ancestral blood-clotting protein [11]. It also suggests that vertebrate blood clotting emerged as a by-product of innate immunity, because the entire functional core of vertebrate clotting shares ancestry with complement proteases.

And if that's not enough, you could check these out:

Banyai, L., Varadi, A. and Patthy, L. (1983). “Common evolutionary origin of the fibrin-binding structures of fibronectin and tissue-type plasminogen activator.” FEBS Letters, 163(1): 37-41.

Bazan, J. F. (1990). “Structural design and molecular evolution of a cytokine receptor superfamily.” Proceedings of the National Academy of Sciences of the United States of America, 87(18): 6934-6938.

Blake, C. C. F., Harlos, K. and Holland, S. K. (1987). “Exon and Domain Evolution in the Proenzymes of Blood Coagulation and Fibrinolysis.” Cold Spring Harbor Symposia on Quantitative Biology: The Evolution of Catalytic Function, LII: 925-932.

Fornace AJ Jr, Cummings DE, Comeau CM, Kant JA, Crabtree GR. “The Structure of the human gamma-fibrinogen gene. Alternate mRNA splicing near the 3' end of the gene produces gamma A and gamma B forms of gamma-fibrinogen.” J Biol Chem. 1984 Oct 25;259(20):12826-30.

Crabtree, G. R., Comeau, C. M., Fowlkes, D. M., Fornace, A. J., Jr., Malley, J. D. and Kant, J. A. (1985). “Evolution and structure of the fibrinogen genes: Random insertion of introns or selective loss?” Journal of Molecular Biology, 185(1): 1-20.  

Di Cera, E., Dang, Q. D. and Ayala, Y. M. (1997). “Molecular mechanisms of thrombin function.” Cell Mol Life Sci, 53(9): 701-730.  

Doolittle, R. F. (1985). “More homologies among the vertebrate plasma proteins.” Biosci Rep, 5(10-11): 877-884.

Doolittle, R. F. (1990). “The Structure and Evolution of Vertebrate Fibrinogen A Comparison of the Lamprey and Mammalian Proteins,” in ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY: FIBRINOGEN, THROMBOSIS, COAGULATION, AND FIBRINOLYSIS. C. Y. Liu and Chien, S. New York, Plenum Press. 281.

Doolittle, R. F. (1992). “A detailed consideration of a principal domain of vertebrate fibrinogen and its relatives.” Protein Science, 1(12): 1563-1577.

Doolittle, R. F. (1992). “Early Evolution of the Vertebrate Fibrinogen Molecule.” Biophysical Journal, 61(2 PART 2): A410.  

Doolittle, R. F. (1992). “Stein and Moore Award address. Reconstructing history with amino acid sequences.” Protein Science, 1(2): 191-200.

Doolittle, R. F. (1993). “The Evolution of Vertebrate Blood Coagulation - a Case of Yin and Yang.” Thrombosis and Haemostasis, V70(N1): 24-28.

Doolittle, R. F. and Feng, D. F. (1987). “Reconstructing the Evolution of Vertebrate Blood Coagulation from a Consideration of the Amino Acid Sequences of Clotting Proteins.” Cold Spring Harbor Symposia on Quantitative Biology: The Evolution of Catalytic Function, LII: 869-874.

Doolittle, R. F., G., Spraggon and J., Everse S. (1997). “Evolution of vertebrate fibrin formation and the process of its dissolution.” Ciba Found Symp, 212: 4-17; discussion 17-23.

Doolittle, R. F. and Riley, M. (1990). “The amino-terminal sequence of lobster fibrinogen reveals common ancestry with vitellogenins.” Biochemical and Biophysical Research Communications, 167(1): 16-19.

Edgington, T. S., Curtiss, L. K. and Plow, E. F. (1985). “A linkage between the hemostatic and immune systems embodied in the fibrinolytic release of lymphocyte suppressive peptides.” Journal of Immunology, 134(1): 471-477.  

Ghidalia, W., Vendrely, R., Montmory, C., Coirault, Y., Samama, M., Lucet, B., Bellay, A. M. and Vergoz, D. (1989). “Overall study of the in vitro plasma clotting system in an invertebrate, Liocarcinus puber (Crustacea Decapoda): Considerations on the structure of the Crustacea plasma fibrinogen in relation to evolution.” Journal of Invertebrate Pathology, 53(2): 197-205.  

Hervio, L. S., Coombs, G. S., Bergstrom, R. C., Trivedi, K., Corey, D. R. and Madison, E. L. (2000). “Negative selectivity and the evolution of protease cascades: the specificity of plasmin for peptide and protein substrates.” Chemistry & Biology, V7(N6): 443-452.  

Hewett-Emmett, D., Czelusniak, J. and Goodman, M. (1981). “The evolutionary relationship of the enzymes involved in blood coagulation and hemostasis.” Annals of the New York Academy of Sciences, 370(20): 511-527.  

Holland, S. K., Harlos, K. and Blake, C. C. F. (1987). “Deriving the generic structure of the fibronectin type II domain from the prothrombin Kringle 1 crystal structure.” EMBO (European Molecular Biology Organization) Journal, 6(7): 1875-1880.  

Jordan, R. E. (1983). “Antithrombin in vertebrate species: conservation of the heparin-dependent anticoagulant mechanism.” Archives of Biochemistry and Biophysics, 227(2): 587-595.  

Kant, J. A., Fornace, A. J., Jr., Saxe, D., Simon, M. J., McBride, O. W. and Crabtree, G. R. (1985). “Evolution and organization of the fibrinogen locus on chromosome 4: Gene duplication accompanied by transposition and inversion.” Proceedings of the National Academy of Sciences of the United States of America, 82(8): 2344-2348.  

Kornblihtt, A. R., Pesce, C. G., Alonso, C. R., Cramer, P., Srebrow, A., Werbajh, S. and Muro, A. F. (1996). “The fibronectin gene as a model for splicing and transcription studies.” FASEB Journal, 10(2): 248-257.  

Laki, K. (1972). “Our ancient heritage in blood clotting and some of its consequences.” Annals of the New York Academy of Sciences, 202(4): 297-307.  

Neurath, H. (1984). “Evolution of proteolytic enzymes.” Science, 224(4647): 350-357.

Neurath, H. (1986). “The Versatility of Proteolytic Enzymes.” Journal of Cellular Biochemistry, 32(1): 35-50.  

Oldberg, A. and Ruoslahti, E. (1986). “Evolution of the fibronectin gene: Exon structure of cell attachment domain.” Journal of Biological Chemistry, 261(5): 2113-2116.  

Opal, S. M. (2000). “Phylogenetic and functional relationships between coagulation and the innate immune response.” Critical Care Medicine, V28(N9 SUPPS): S77-S80.  

Pan, Y. and Doolittle, R. F. (1991). “Distribution of Introns in Lamprey Fibrinogen Genes.” Journal of Cellular Biochemistry Supplement(15 PART D): 75.  

Pan, Y. and Doolittle, R. F. (1992). “cDNA sequence of a second fibrinogen alpha chain in lamprey: an archetypal version alignable with full-length beta and gamma chains.” Proceedings of the National Academy of Sciences of the United States of America, 89(6): 2066-2070.

Patthy, L. (1985). “Evolution of the Proteases of Blood Coagulation and Fibrinolysis by Assembly from Modules.” Cell, 41(3): 657-664.

Patthy, L. (1990). “Evolution of blood coagulation and fibrinolysis.” Blood Coagulation and Fibrinolysis, 1(2): 153-166.

Patthy, L. (1990). “Evolutionary Assembly of Blood Coagulation Proteins.” Seminars in Thrombosis and Hemostasis, 16(3): 245-259.

Patthy, L. (1999). “Genome evolution and the evolution of exon-shuffling—a review.” Gene, 238(1): 103-114.

Roberts, Lewis R., Nichols, Lanita A. and Holland, Lene J. (1995). “CDNA and amino-acid sequences and organization of the gene encoding the B-beta subunit of fibrinogen from Xenopus laevis.” Gene (Amsterdam), 160(2): 223-228.  

Sosnoski, D. M., Emanuel, B. S., Hawkins, A. L., Van Tuinen, P., Ledbetter, D. H., Nussbaum, R. L., Kaos, F. T., Schwartz, E., Phillips, D. and et al. (1988). “Chromosomal localization of the genes for the vitronectin and fibronectin receptors .alpha. subunits and for platelet glycoproteins IIb and IIIa.” Journal of Clinical Investigation, 81(6): 1993-1998.  

Wang, Y. Z., Patterson, J., Gray, J. E., Yu, C., Cottrell, B. A., Shimizu, A., Graham, D., Riley, M. and Doolittle, R. F. (1989). “Complete sequence of the lamprey fibrinogen .alpha. chain.” Biochemistry, 28(25): 9801-9806.  

Xu, X. and Doolittle, R. F. (1990). “Presence of a vertebrate fibrinogen-like sequence in an echinoderm.” Proceedings of the National Academy of Sciences of the United States of America, 87(6): 2097-2101.

Zhang, Y. L., Hervio, L., Strandberg, L. and Madison, E. L. (1999). “Distinct contributions of residue 192 to the specificity of coagulation and fibrinolytic serine proteases.” Journal of Biological Chemistry, V274(N11): 7153-7156.

Zimmermann, E. (1983). “[The evolution of the coagulation system from primitive defense mechanisms].” Behring Institute Mitteilungen, 82(73): 1-12.  

The 2.0-Å crystal structure of tachylectin 5A provides evidence for the common origin of the innate immunity and the blood coagulation systems

Davidson CJ, Tuddenham EG, McVey JH. 450 million years of hemostasis J Thromb Haemost. 2003 Jul;1(7):1487-94.

[Ichneumon]

Evolutionary theory predicted that there should be transitional forms between the reptilian-style jaw joint and the mammalian-style jaw joint (the earliest mammals evolved from reptiles). For years creationists crowed about the "missing links", and made their own predictions that not only would there be no such transitional fossils found, but that any creature with a jaw that was transitional between that of reptiles and mammals would die of starvation, since such a "half and half" jaw joint was "obviously" mechanically unworkable. Nonetheless, biologists kept searching for the fossils predicted by evolution, and not only found one or two, but found a *wealth* of them which provide a *very* complete and smooth transitional sequence -- exactly as evolution predicted. Oddly enough, I never hear the creationists bring that one up...

Reptile -> Mammal evolutionary transition:

Example 2: reptile-mammals

Figure 1.4.1. The jaws of three vertebrates—mammal, therapsid, and pelycosaur. A side view of three idealized skulls of mammals, therapsids (mammal-like reptiles), and pelycosaurs (early reptiles). The figure shows the differences between mammal and reptilian jaws and ear-bone structures. The jaw joint is shown as a large black dot, the quadrate (mammalian anvil or incus) is in turquoise, the articular (mammalian hammer or malleus) is in yellow, and the angular (mammalian tympanic annulus) is in pink. Note how, in the reptile, the jaw joint is formed between the blue quadrate and the yellow articular (with the pink angular close by), and how, in the mammal, the jaw joint is formed between the squamosal above and the dentary below. In the reptile, the squamosal is just above and contacting the quadrate. Advanced therapsids have two jaw joints: a reptile-like joint and a mammal-like joint (Figure based on Kardong 2002, pp. 275, reproduced with permission from the publisher, Copyright © 2002 McGraw-Hill)

We also have an exquisitely complete series of fossils for the reptile-mammal intermediates, ranging from the pelycosauria, therapsida, cynodonta, up to primitive mammalia (Carroll 1988, pp. 392-396; Futuyma 1998, pp. 146-151; Gould 1990; Kardong 2002, pp. 255-275). As mentioned above, the standard phylogenetic tree indicates that mammals gradually evolved from a reptile-like ancestor, and that transitional species must have existed which were morphologically intermediate between reptiles and mammals—even though none are found living today. However, there are significant morphological differences between modern reptiles and modern mammals. Bones, of course, are what fossilize most readily, and that is where we look for transitional species from the past. Osteologically, two major striking differences exist between reptiles and mammals: (1) reptiles have at least four bones in the lower jaw (e.g. the dentary, articular, angular, surangular, and coronoid), while mammals have only one (the dentary), and (2) reptiles have only one middle ear bone (the stapes), while mammals have three (the hammer, anvil, and stapes) (see Figure 1.4.1).

Early in the 20^th century, developmental biologists discovered something that further complicates the picture. In the reptilian fetus, two developing bones from the head eventually form two bones in the reptilian lower jaw, the quadrate and the articular (see the Pelycosaur in Figure 1.4.1). Surprisingly, the corresponding developing bones in the mammalian fetus eventually form the anvil and hammer of the unique mammalian middle ear (also known more formally as the incus and malleus, respectively; see Figure 1.4.2) (Gilbert 1997, pp. 894-896). These facts strongly indicated that the hammer and anvil had evolved from these reptilian jawbones—that is, if common descent was in fact true. This result was so striking, and the required intermediates so outlandish, that many anatomists had extreme trouble imagining how transitional forms bridging these morphologies could have existed while retaining function. Young-earth creationist Duane Gish stated the problem this way:

"All mammals, living or fossil, have a single bone, the dentary, on each side of the lower jaw, and all mammals, living or fossil, have three auditory ossicles or ear bones, the malleus, incus and stapes. ... Every reptile, living or fossil, however, has at least four bones in the lower jaw and only one auditory ossicle, the stapes. ... There are no transitional fossil forms showing, for instance, three or two jawbones, or two ear bones. No one has explained yet, for that matter, how the transitional form would have managed to chew while his jaw was being unhinged and rearticulated, or how he would hear while dragging two of his jaw bones up into his ear." (Gish 1978, p. 80)

Figure 1.4.2. A comparison of the ears of reptiles and mammals. The reptile ear is shown on the left, the mammal ear on the right. As in Figure 1.4.1, the quadrate (mammalian anvil or incus) is in turquoise and the articular (mammalian hammer or malleus) is in yellow. The stapes is shown in brown. Note how the relative arrangement of these bones is similar in both taxa, in the order of inner ear-stapes-quadrate-articular.

Gish was incorrect in stating that there were no transitional fossil forms, and he has been corrected on this gaff numerous times since he wrote these words. However, Gish's statements nicely delineate the morphological conundrum at hand. Let's review the required evolutionary conclusion. During their evolution, two mammalian middle ear bones (the hammer and anvil, aka malleus and incus) were derived from two reptilian jawbones. Thus there was a major evolutionary transition in which several reptilian jawbones (the quadrate, articular, and angular) were extensively reduced and modified gradually to form the modern mammalian middle ear. At the same time, the dentary bone, a part of the reptilian jaw, was expanded to form the major mammalian lower jawbone. During the course of this change, the bones that form the hinge joint of the jaw changed identity. Importantly, the reptilian jaw joint is formed at the intersection of the quadrate and articular whereas the mammalian jaw joint is formed at the intersection of the squamosal and dentary (see Figure 1.4.1).

How could hearing and jaw articulation be preserved during this transition? As clearly shown from the many transitional fossils that have been found (see Figure 1.4.3), the bones that transfer sound in the reptilian and mammalian ear were in contact with each other throughout the evolution of this transition. In reptiles, the stapes contacts the quadrate, which in turn contacts the articular. In mammals, the stapes contacts the incus, which in turn contacts the malleus (see Figure 1.4.2). Since the quadrate evolved into the incus, and the articular evolved into the malleus, these three bones were in constant contact during this impressive evolutionary change. Furthermore, a functional jaw joint was maintained by redundancy—several of the intermediate fossils have both a reptilian jaw joint (from the quadrate and articular) and a mammalian jaw joint (from the dentary and squamosal). Several late cynodonts and Morganucodon clearly have a double-jointed jaw. In this way, the reptilian-style jaw joint was freed to evolve a new specialized function in the middle ear. It is worthy of note that some modern species of snakes have a double-jointed jaw involving different bones, so such a mechanical arrangement is certainly possible and functional.

Since Figure 1.4.3 was made, several important intermediate fossils have been discovered that fit between Morganucodon and the earliest mammals. These new discoveries include a complete skull of Hadrocodium wui (Luo et al. 2001) and cranial and jaw material from Repenomamus and Gobiconodon (Wang et al. 2001). These new fossil finds clarify exactly when and how the malleus, incus, and angular completely detached from the lower jaw and became solely auditory ear ossicles.

Recall that Gish stated: "There are no transitional fossil forms showing, for instance, three or two jawbones, or two ear bones" (Gish 1978, p. 80). Gish simply does not understand how gradual transitions happen (something he should understand, obviously, if he intends to criticize evolutionary theory). These fossil intermediates illustrate why Gish's statement is a gross mischaracterization of how a transitional form should look. In several of the known intermediates, the bones have overlapping functions, and one bone can be called both an ear bone and a jaw bone; these bones serve two functions. Thus, there is no reason to expect transitional forms with intermediate numbers of jaw bones or ear bones. For example, in Morganucodon, the quadrate (anvil) and the articular (hammer) serve as mammalian-style ear bones and reptilian jaw bones simultaneously. In fact, even in modern reptiles the quadrate and articular serve to transmit sound to the stapes and the inner ear (see Figure 1.4.2). The relevant transition, then, is a process where the ear bones, initially located in the lower jaw, become specialized in function by eventually detaching from the lower jaw and moving closer to the inner ear.

Figure 1.4.3. A comparison of the jawbones and ear-bones of several transitional forms in the evolution of mammals. Approximate stratigraphic ranges of the various taxa are indicated at the far left (more recent on top). The left column of jawbones shows the view of the left jawbone from the inside of the mouth. The right column is the view of the right jawbone from the right side (outside of the skull). As in Figure 1.4.1, the quadrate (mammalian anvil or incus) is in turquoise, the articular (mammalian hammer or malleus) is in yellow, and the angular (mammalian tympanic annulus) is in pink. For clarity, the teeth are not shown, and the squamosal upper jawbone is omitted (it replaces the quadrate in the mammalian jaw joint, and forms part of the jaw joint in advanced cynodonts and Morganucodon). Q = quadrate, Ar = articular, An = angular, I = incus (anvil), Ma = malleus (hammer), Ty = tympanic annulus, D = dentary. (Reproduced from Kardong 2002, pp. 274, with permission from the publisher, Copyright © 2002 McGraw-Hill)

The above is from 29+ Evidences for Macroevolution, which compiles several hundred transitional fossils, which is itself just a *SMALL* sampling of the ENORMOUS numbers of fine transitional sequences found in the fossil record and well known to anyone who has bothered to CRACK OPEN A BOOK -- or even do a websearch -- in the past 25 years or so... So what's the anti-evolutionists' excuse for remaining abysmally ignorant of such things, and repeatedly making the false claim that there are "no" transitional fossils, etc.?

Here's another look:

Mammal-Like Reptiles

As previously stated, a succession of transitional fossils exists that link reptiles (Class Reptilia) and mammals (Class Mammalia). These particular reptiles are classifie as Subclass Synapsida. Presently, this is the best example of th e transformation of one major higher taxon into another. The morphologic changes that took place are well documented by fossils, beginning with animals essentially 100% reptilian and resulting in animals essentially 100% mammalian. Therefore, I have chosen this as the example to summarize in more detail (Table 1, Fig. 1).

Skulls and jaws of synapsid reptiles and mammals; left column side view of skull; center column top view of skull; right column side view of lower jaw. Hylonomus modified from Carroll (1964, Figs. 2,6; 1968, Figs. 10-2, 10-5; note that Hylonomus is a protorothyrod, not a synapsid). Archaeothyris modified from Reisz (1972, Fig. 2). Haptodus modified from Currie (1977, Figs, 1a, 1b; 1979, Figs. 5a, 5b). Sphenacodo n modified from Romer & Price (1940, Fig. 4f), Allin (1975, p. 3, Fig. 16);note: Dimetrodon substituted for top view; modified from Romer & Price, 1940, pl. 10. Biarmosuchus modified from Ivakhnenko et al. (1997, pl. 65, Figs. 1a, 1B, 2); Alin & Hopson (1992; Fig. 28.4c); Sigogneau & Tchudinov (1972, Figs. 1, 15). Eoarctops modified from Broom (1932, Fig. 35a); Boonstra (1969, Fig. 18). Pristerognathus modified from Broom (1932, Figs 17a, b,c); Boonstra (1963, Fig. 5d). Procynosuchus modified from Allin & Hopson (1992, Fig. 28.4e); Hopson (1987, Fig. 5c); Brink (1963, Fig. 10a); Kemp (1979, Fig. 1); Allin (1975, p. 3, Fig. 14). Thrinaxodon modified from Allin & Hopson (1992, Fig. 28.4f);Parrington (1946, Fig. 1); Allin (1975, p. 3, Fig. 13). Probainognathus modified from Allin & Hopson (1992, Fig. 28.4g); Romer (1970, Fig. 1); Allin (1975, p. 3, Fig. 12). Morga nucodon modified from Kermack, Mussett, & Rigney (1981, Figs. 95, 99a; 1973, Fig. 7a); Allin (1975, p. 3, Fig. 11). Asioryctes modified from Carroll (1988, Fig. 20-3b). Abbreviations: ag = angular; ar = articular; cp = coronoid process; d = dentary; f = lateral temporal fenestra; j = jugal; mm = attachment site for mammalian jaw muscles; o = eye socket; po = post orbital; q = quadrate; rl = reflected lamina; sq = squamosal; ty = tympanic.

TAXONOMY	LATERAL TEMPORAL FENESTRA	LOWER JAW DENTARY	TEETH	LOWER JAW: POST- DENTARY BONES	MIDDLE EAR & JAW ARTICULATION
M: Early Placental mammals Asioryctes Upper Cretaceous	Merged with eye socket; cheek arch bowed out laterally	100% of jaw length is the den- tary; condylar process in contact with squamosal	Fully differentiated teeth; incisors, canines, premolars; one tooth replacement	No post-dentary bones	3 middle ear bones (stapes, incus, malleus) + tympanic; squamosal-dentary jaw joint
L: "Pantothere" mammals Amphitherium Middle/Upper Jurassic	X	100% of jaw length is the den-  tary; condylar process contacts squamosal	Fully differentiated teeth; incisors, canines, premolars; one tooth replacement	Post-dentary bones migrated to middle ear	Probably 3 middle ear bones (stapes, incus, malleus) + tympanic; squamosal-dentary jaw joint
K: Morganucodontid mammals Morganucodon  Upper Triassic & Lower Jurassic	Merged with eye socket; cheeck arch bowed out laterally	100% of jaw length is the den- tary; condylar process expanded posteriorly to make contact with squamosal	Fully differentiated teeth; incisors, canines, premolars; one tooth replacement	20% of jaw length; reflected lamina decreased to narrow ribbon-like horseshoe	Stapes extends from inner ear capsule to quadrate; quadrate tiny; both quadrate-articular and squamosal-dentary jaw joints
J: Chiniquodontid cynodonts Probainognathus Middle Triassic	Much larger than eye socket; 40- 45% of skull length; expanded posterioirly, medially, & laterally; midline of skull narrow sagittal crest; chek arch bowed out laterally	95% of jaw length is the dentary; large coronoid process expanded posteriorly; condylar process expanded posteriorly	Large single canine; cheek teeth multicusped; tooth replacement reduced	20% of jaw length; angular notch widened ventrally; width of main part of angular decreased; reflec - ted lamina decreased to narrow ribbon-like horseshoe	Stapes extends from inner ear capsule to quadrate; quadrate tiny; quadrate-articular joint
I:Galesaurid cynodonts Thrinaxodon Lower Triassic	Much larger than eye socket; 40% of skull length; expanded pos- terioirly, medially, & laterally; midline of skull narrow sagittal crest; chek arch bowed out laterally	85% of jaw length is the dentary; large coronoid process expanded to top of eye socket and pos- teriorly; jaw muscles attached to most of coronoid process	Large single canine; cheek teeth multicusped; tooth replacement reduced	25% of jaw length; angular notch widened ventrally; width of reflec- ted lamina decreased; width of main part of angular decreased	Stapes extends from inner ear capsule to quadrate; quadrate small; quadrate-articular jaw joint
H: Procynosuchid cynodonts Procynosuchus upper Upper Permian	Much larger than eye socket; 40% of skull length; expanded pos- terioirly, medially, & laterally; midline of skull narrow sagittal crest; chek arch bowed out laterally	75-80% of jaw length is the den- tary; coronoid process expanded to near top of eye socket and posteriorly; jaw muscles  attached to dorsal part of coronoid process	Large single canine; cheek teeth multicusped	30% of jaw length; angular notch widened ventrally; width of reflected lamina decreased	Stapes extends from inner ear capsule to quadrate; quadrate small; quadrate-articular jaw joint
G: Early Therocephalians Pristerognathus lower Upper Permian	Larger than eye socket; expanded posteriorly and medially; 30% of skull length	75-80% of jaw length is the den- tary; posterior end of dentary expanded posteriorly and dorsally into narrow blade-like coronoid process; rises to middle of eye socket	Large single canine; other teeth simple cones.	35% of jaw length; angular notch deepened into a cleft; reflected lamina large, broad, blade-like	Stapes extends from inner ear capsule to quadrate; quadrate small; quadrate-articular jaw joint
F: Early Gorgonopsians Eoarctops lower Upper Permian	Slightly larger than eye socket; expanded posteriorly and medially (minimal); 20-25% of skull length	65-75% of jaw length is the den- tary; posterior end of dentary slightly expanded posteriorly and dorsally as incipient coronoid process	Large single canine; other teeth simple cones.	40% of jaw length; angular notch deepened into a cleft; reflected lamina large, broad, blade-like	Stapes extends from inner ear capsule to quadrate; quadrate- articular jaw joint
E: Eotitanosuchians Sphenacodon Lower Permian	Small; slightly smaller than eye socket; slightly expanded posteriorly and medially	65-75% of jaw length is the den- tary; posterodorsal edge rises broadly but slightly above tooth row	Large single canine; other teeth simple cones.	40% of jaw length; angular notch deepened into a cleft; reflected lamina large, broad, blade-like	Stapes extends from inner ear capsule to quadrate;  quadrate- articular jaw joint
D: Late sphenacodonts Sphenacodon Upper Pennsylvanian	Small; smaller than eye socket; confined to one side of skull	65% of jaw length is the dentary; posterodorsal edge rises broadly but slightly above the tooth row	Enlarged incipient canines; other teeth simple cones	60% of jaw length; venntral edge of angular notched ("angular notch") offsetting a short pro- tusion (reflected lamina)	Stapes extends from inner ear capsule to quadrate; quadrate large and plate-like; quadrate- articular jaw joint
C: Early spenacodonts Haptodus Upper Pennsylvanian	Tiny; smaller than eye socket; confined to one side of skull	65-75% of jaw length is the den- tary; posterodorsal edge rises broadly but slightly above tooth row	Undifferentiated; slightly enlarged incipient canines just behind nares	70% of jaw length; ventral edge of angular with shallow indentation	Stapes extends from inner ear capsule to quadrate; quadrate- articular jaw joint
B: Early ophiacodonts Archaothyris upper Middle Pennsylvanian	Tiny; smaller than eye socket; confined to one side of skull	x	Undifferentiated; slightly enlarged incipient canines just behind nares	x	Stapes extends from inner ear capsule to quadrate; quadrate- articular jaw joint
A: Protorothyrids Hylonomus lower Middle Pennsylvanian	Absent	65-75% of jaw length is the den- tary; posterodorsal edge rises broadly but slightly above tooth row	Undifferentiated; slightly enlarged incipient canines just behind nares	70% of jaw length; ventral edge of angular continuous	Stapes extends from inner ear capsule to quadrate; quadrate- articular jaw joint

Table 1: Morphology of synapsid reptiles and mammals (Note that Hylonomus is a protothyrid, not a synapsid). Data from references cited in text.

Modern reptiles and mammals are very distinctive, easily diagnosable, and do not intergrade. Reptiles are covered by scales, mammals by hair; reptiles are cold-blooded, mammals warm-blooded; reptiles do not suckle their young, mammals have mammary glands; reptiles have sprawling posture, mammals have upright posture. Most of these features are soft part anatomy or physiology that very rarely fossilize (although dinosaur skin impressions are known from Cretaceous sediments, and imprints of mammal hair are known from Eocene bats from Germany; Franzen, 1990). In the fossil record, we must look to skeletal features.

There are many skeletal features which allow us to distinguish the reptiles from the mammals (Carroll, 1988; Table 1, rows A, M). The single most important defining characteristic is the nature of the articulation of the lower jaw to the skull (Simpson, 1959). In reptiles, multiple bones comprise the lower jaw. A small bone at the posterior end of the lower jaw, the articular, articulates with the quadrate bone of the skull (Simpson, 1959; Carroll, 1988). In mammals, one large bone, the dentary, comprises the lower jaw. It articulates with the squamosal bone of the skull (Simpson, 1959; Carroll, 1988).

From comparative anatomy studies, it is certain that most of the bones of the reptiles and mammals are homologous (Crompton & Parker, 1978; Carroll, 1988). Of greatest importance, the middle ear bones of mammals (stapes, incus, malleus, and tympanic) are homologous with several of the skull and jaw bones of reptiles (stapes, quadrate, articular, and angular, respectively; Romer, 1956, p. 33-38, 1970a; Allin, 1975, 1986; Allin & Hopson, 1992; Crompton & Parker, 1978; Hopso n, 1987, 1994; Carroll, 1988). One group of reptiles, the synapsids (Subclass Synapsida), share with the mammals an additional homologous structure: the lateral temporal fenestra, which is an opening in the skull behind the eye socket at the triple junction between the squamosal, jugal , and post orbital bones (Broom, 1932; Frazetta, 1968; Kemp, 1982; Carroll, 1988). A band of bone composed of the jugal and the squamosal is adjacent to the lateral temporal fenestra (Broom, 1932; Kemp, 1982; Carroll, 1988). This is the cheek arch so characteristic of mammal skulls (Broom, 1932; Kemp, 1982; Carroll, 1988). Therefore, synapsids are commonly named the “mammal-like reptiles.”

The presence of diagnosable morphologic differences between reptiles (including the oldest reptiles and the oldest synapsids) and mammals distinguishes them as distinct taxa. This allows us to test evolution by looking for transitional forms between the two. Because many of the bones are homologous, we should find evidence illustrating how these bones were modified over time to become the new bones. Furthermore, these morphologic changes should happen in parallel and in geochronologic succession.

Synapsid reptiles inhabited Pangea from the Middle Pennsylvanian through the Early Jurassic (Kemp, 1982, 1985; Sloan, 1983; Carroll, 1988; Hopson, 1969, 1987, 1994; Hopson & Crompton, 1969; Hotton, et al., 1986; Crompton & Jenkins, 1973; Sidor & Hopson, 1998; Romer & Price, 1940; Broom, 1932; Boonstra, 1963, 1969, 1971; Tchudinov, 1983; Olson, 1944; Tatarinov, 1974; Vyushkov, 1955; Efremov, 1954). From the Early Permian through the Early Triassic, they were the largest and most abundant land animals (Sloan, 1983; Colbert, 1965). Though much less well known to the general public than dinosaurs, one of the “cereal box dinosaurs,” Dimetrodon (the sail-backed reptile), is a synapsid, not a dinosaur (Romer & Price, 1940; Carroll, 1988). The oldest mammals are Late Triassic (Kemp, 1982; Carroll, 1988). Below is a discussion of the geochronologic succession linking synapsids and mammals. The oldest reptiles (named protorothyrids; Carroll, 1964, 1988, p. 192-199) are from the lower Middle Pennsylvanian, and the oldest synapsids (Reisz, 1972) are from the upper Middle Pennsylvanian, both of Nova Scotia. Upper Pennsylvanian and Lower Permian forms are known primarily from the midcontinent and Permian Basin region of the United States (Romer & Price, 1940; Currie, 1977, 1979; Kemp, 1982; Sloan, 1983). The basal Upper Permian forms are known from Russia (Tchudinov, 1960, 1983; Efremov, 1954; Olson, 1962; Sigogneau & Tchudinov, 1972; Ivakhnenko et al., 1997). Most of the Upper Permian and Lower Triassic succession is known from southern Africa, especially the Great Karoo of South Africa (Broom, 1932; Boonstra, 1963, 1969, 1971; Hopson & Kitching, 1972; Kemp, 1982; Sloan, 1983). The Middle Triassic forms are from South America (Romer, 1969a, 1969b, 1970b, 1973; Romer & Lewis, 1973; Bonaparte & Barbarena, 1975), and the Upper Triassic and Lower Jurassic mammals are known from Eurasia (Kermack, Mussett, & Rigney, 1973, 1981; Kemp, 1982). Subsequent Mesozoic mammals are known from all over the world (Simpson, 1928; Lillegraven et al., 1979).

When placed in proper geochronologic succession, the synapsids naturally form a succession of taxa (genera and families) that progressively become more mammal-like and less reptile-like (Kemp, 1982, 1985; Sloan, 1983; Sidor & Hopson, 1998; Hopson, 1987, 1994). Morphologic changes, summarized in Table 1 and Figure 1, affect the entire skeletal anatomy of these animals, but are most clearly displayed in their skulls.

The lateral temporal fenestra increased in size from a tiny opening smaller than the eye socket to a giant opening occupying nearly half the length of the skull. Ultimately, it merged with the eye socket, thus producing the full development of the cheek arch so characteristic of mammals (Broom, 1932; Frazetta, 1968; Kemp, 1982; Sloan, 1983; Hopson, 1987, 1994; Carroll, 1988).

Successively, the relative proportion of the lower jaw comprised of the dentary bone (teeth-bearing bone) gradually increased until the entire lower jaw consisted of the dentary (Kemp, 1982; Sloan, 1983; Carroll, 1988; Hopson, 1987, 1994). In Pennsylvanian and Lower and basal Upper Permian synapsids, the postero-dorsal edge of the lower jaw rose broadly but only slightly above the level of the tooth row (Romer & Price, 1940; Currie, 1977, 1979; Ivakhnenko et al., 1997; Tchudinov, 1960, 1983; Efremov, 1954; Olson, 1962; Sigogneau & Tchudinov, 1972; Hopson, 1987, 1994). In succeeding forms, the posterior part of the dentary expanded dorsally and posteriorly as a blade-like process, and progressively became larger (Broom, 1932; Boonstra, 1963, 1969, 1971; Sigogneau, 1970; Brink, 1963; Kemp, 1979; Hopson, 1987, 1994), forming the coronoid process (Parrington, 1946; Fourie, 1974; Romer, 1969b, 1970b, 1973; Hopson, 1987, 1994) to which the mammalian-type jaw musculature is attached (Barghusen, 1968; Bramble, 1978; Crompton, 1972; Crompton & Parker, 1978; Kemp, 1982; Sloan, 1983; Carroll, 1988). Concomitantly, the post-dentary bones progressively reduced in size (Allin, 1975; Crompton, 1972; Crompton & Parker, 1978; Kemp, 1982; Sloan, 1983; Carroll, 1988; Hopson, 1987, 1994).

Beginning with the Upper Pennsylvanian sphenacodonts, a notch developed in the angular bone that offsets a projection, the reflected lamina (Allin, 1975; Allin & Hopson, 1992; Hopson, 1987, 1994; Romer & Price, 1940; Currie, 1977, 1979; Kemp, 1982; Sloan, 1983; Carroll, 1988). The reflected lamina first became a large blade-like flange (Allin, 1975; Allin & Hopson, 1992; Hopson, 1987, 1994; Ivakhnenko et al., 1997; Tchudinov, 1960, 1983; Efremov, 1954; Olson, 1962; Sigogneau & Tchudinov, 1972; Broom, 1932; Sigogneau, 1970; Boonstra, 1963, 1969, 1971), and then was progressively reduced to a delicate horseshoe-shaped bone (Allin, 1975; Allin & Hopson, 1992; Hopson, 1987, 1994; Brink, 1963; Parrington, 1946; Fourie, 1974; Romer, 1969b, 1970b, 1973; Kermack, Mussett, & Rigney, 1973, 1981; Kemp, 1979, 1982; Sloan, 1983; Carroll, 1988).

Simultaneously, the quadrate progressively decreased in size (Allin, 1975; Allin & Hopson, 1992; Hopson, 1987, 1994; Kemp, 1982; Sloan, 1983; Carroll, 1988). The articular did not decrease in size much, being small initially, but developed a downward-pointing prong (Allin, 1975; Allin & Hopson, 1992; Hopson, 1987, 1994; Kemp, 1982; Sloan, 1983; Carroll, 1988). In the synapsids, the lower jaw was hinged to the skull by the articular and quadrate bones (Crompton, 1972; Crompton & Parker, 1978; Allin, 1975; Allin & Hopson, 1992; Hopson, 1987, 1994). Thus they are classified as reptiles (Simpson, 1959; Kemp, 1982; Sloan, 1983; Carroll, 1988). As the quadrate and articular became smaller, they were relieved of their solid suture to the dentary and skull (Crompton, 1972; Allin, 1975, 1986; Allin & Hopson, 1992; Hopson, 1987, 1994; Crompton & Parker, 1978; Kemp, 1982; Sloan, 1983; Carroll, 1988). A projection of the dentary extended posteriorly and made contact with the squamosal. Morganucodon possessed the mammalian dentary-squamosal jaw joint adjacent to the reptilian articular-quadrate jaw joint (Kermack, Mussett, & Rigney, 1973, 1981; Carroll, 1988). It is classified as the first mammal, but it is a perfect intermediate. Now that a new jaw joint was established, the quadrate and articular were subsequently relieved of that function (Crompton, 1972; Allin, 1975, 1986; Allin & Hopson, 1992; Hopson, 1987, 1994; Crompton & Parker, 1978; Kemp, 1982; Sloan, 1983; Carroll, 1988). Ultimately, in Middle and Upper Jurassic mammals, the tiny quadrate, articular, and ring-like angular migrated as a unit to the middle ear where they joined the stapes and became the incus, malleus, and tympanic bones (Allin, 197 5, 1986; Allin & Hopson, 1992; Hopson, 1987, 1994; Kemp, 1982; Sloan, 1983; Carroll, 1988).

Progressively, the teeth became differentiated. The large canines developed first, followed by the development of multicusped cheek teeth, reduced tooth replacement (Osborn & Crompton, 1973; Crompton & Parker, 1978), and finally full y differentiated incisors, canines, premolars, and molars with one tooth replacement during life (Kemp, 1982; Hopson, 1994).

Many other morphologic changes are documented in the fossil record. These demonstrate the morphologic and geochronologic succession from sprawling limb posture to upright limb posture of mammals (Jenkins, 1971; Romer & Lewis, 197 3; Kemp, 1982; Carroll, 1988; Hopson, 1994). As Jenkins (1971, p. 210) stated, “In details of morphology and function, the cynodont post-cranial skeleton should be regarded as neither ‘reptilian’ nor ‘mammalian’ but as transitional between the two classes .” Other changes have been adequately summarized elsewhere (Kemp, 1982; Sloan, 1983; Carroll, 1988; Hopson, 1994). Obviously, fundamental physiologic changes must have taken place as well, many of which are not directly preserved in the fossil record, though some can be inferred from the skeletal anatomy (Findlay, 1968; Kemp, 1982; Sloan, 1983, Carroll, 1988; Hopson, 1994).

This is well documented in the fossil record by a massive volume of incontrovertible data that cannot be explained away. Such large-scale, progressive, continuous, gradual, and geochronologically successive morphologic change (Sidor & Hopson, 1998) is descent with modification, and provides compelling evidence for evolution on a grand scale.

(The above is from The Fossil Record: Evolution or "Scientific Creation", which is yet ANOTHER source the anti-evolutionists are obviously completely ignorant of -- not that that stops them from spouting off falsehoods about the subject anyway...

[Ichneumon]

Here, read this and get a clue: Thermodynamics, Evolution and Creationism

[Yo-Yo]

Tastes Great! Less Filling!

Maybe you're BOTH right. Who is to say that the original spark of life came from a Divine intervention, but today's biodiversity came about from evolution, an ongoing process?

2 Peter 3:8: "But you must not forget, dear friends, that a day is like a thousand years to the Lord, and a thousand years is like a day."

[Natty Boh III]

I'm no scientist, but I have to say through my layman's perspective, this is terribly unconvincing.

Evolution defies the Second Law of Thermodynamics. In plain terms, it expects people to accept, on blind, unverifiable faith, that out of disorder, and through a bunch of accidents, order is created--, disorder becomes order. Another way of looking at that would be to think of a deck of cards, carefully shuffled and thrown high in the air. With the expectation that eventually an “accident” would happen which would cause all 52 cards in the deck, to fall in perfect order, and perfectly aligned.

Working from my admittedly hazy recollection of high school statistics and an Excel spreadsheet, I think the chances of throwing a deck of cards in the air and having it come down in order is 1 in (52x51x50x49....x1) or 8.07^67. Seems like a small chance.

But then compare it to the number of chances there are in the natural world. Say you have a bacterium that divides once a day. Each division is like throwing the genetic deck of cards in the air. So first you have 1 bacterium, then you have 2, then 4, then 8 and so on. After a year, you have 3.8^109 bacteria -- that's way bigger than the 1 in 8.07^67 chance of getting the cards in order. In other words, even though the chances of getting the cards in order is so small, you will have so many bacteria that one of them is almost guaranteed to have the genetic cards in order. Even if you assume mutations only occur once in every trillion tosses of the genetic cards, it still seems like the chances of getting the generic cards in order is almost 100%.

Can someone with better math skills confirm this?

[Dimensio]

Evolution defies the Second Law of Thermodynamics.

I stopped here. Anyone who pulls the 2nd LoT as an argument against evolution is either fundamentally ignorant of science, in which case nothing that they say can be trusted, or shamelessly lying, in which case nothing that they can be trusted.

[Ichneumon]

Another way of looking at that would be to think of a deck of cards, carefully shuffled and thrown high in the air. With the expectation that eventually an “accident” would happen which would cause all 52 cards in the deck, to fall in perfect order, and perfectly aligned. [FN2]

Probability of Abiogenesis FAQs

And for a taste of just how *much* evolution can speed up things over purely random processes like the one you *incorrectly* try to use as an analogy for evolutionary processes, here's an older post of mine:

Or are you one of those who insist that a room full of monkeys with keyboards can write the complete works of Shakespeare?

In theory? Yes they can, if you're willing to wait long enough (where "enough" is an amount of time that boggles the imagination). In practice (by simple random output)? No they can't.

But they can do it pretty quickly and easily if a replication and selection process is involved.

You wanted to see a calculation, so let's do one.

Consider the Shakespeare phrase, "If you can look into the seeds of time, and say which grain will grow and which will not, speak then unto me." That's 109 characters (including spaces and punctuation). Upper and lower case letters, plus digits and puntuaction, make up a pool of about 70 different characters. This means that the odds of producing the Shakespeare phrase in one random trial is 1 out of 70¹⁰⁹, or 1 in 1,305,227,939,201,292,014, 528,313,176,276,968,928,001, 249,110,077,400,839,115,038, 451,821,150,802,274,449,576, 205,527,736,070,000,000,000, 000,000,000,000,000,000,000, 000,000,000,000,000,000,000, 000,000,000,000,000,000,000, 000,000,000,000,000,000,000, 000,000,000,000,000.

Needless to say, that's a big number. It's so huge that if every atom in the universe (about 10⁸⁰ of them) were a computer capable of making a billion (1,000,000,000) random trials per second, the expected time required to produce the above line from Shakespeare would be 2,585,011,097,170,911,314,802,759,827,024,569,612,393, 783,728,161,759,843,736,212,615,624,189,581,658,716,078, 309,043,891,309 times the expected lifespan of the universe. That's close enough to "never" in my book.

But that's for *purely* random production process. How much do you think an evolutionary process could cut down that figure? Knock a few zeros off the end, maybe?

Well let's try it. Using an evolutionary process, which couples random variation with replication and selection and *nothing* else, the above Shakespeare phrase can be produced on a *single* computer (mine), using a breeding population of 1024 character strings in a whopping... 15 seconds (using this applet):

Generation: 0
Tries <= 1024
Best Critter: "xSeOSEpc3Lm6rnRWnpFYL?QEDY7a67XlfRoJ0e8Len'X'1u'BhdrNqSNaXr7kVjondNozkf2CH9d96SaI?'f43M.CUGJ5XHbqfeR.UJP'tgNP"
Score (0 is best) 101

Generation: 100
Tries <= 26624
Best Critter: "vf,ioV c3RKlooioifBFQXh, PeHTskof!oJ0e,Lrn'X'1u BhkchESNaXr kVjo dNozpanSI div1Qwi8h taQ,jswMkk,us1S'ugYtmm7."
Score (0 is best) 72

[...]

Generation: 1115
Tries <= 286464
Best Critter: "If you can look into the seeds of time, and say which grain will grow and which will not, speak then unto me."
Score (0 is best) 0

Checked 286464 critters in 15 seconds == 19097 tries/sec.

Hmm, 15 seconds is a hell of a lot faster than zillions of times the lifespan of the universe, isn't it? Evolution sped things up (compared to a purely random process) by a factor of more than 10¹⁹⁵ -- that's a "1" followed by a hundred and ninety-five zeros, or: 1, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000, 000.

Lesson: Even simple evolutionary processes are *incredibly* more efficient and effective than simple randomness alone. Evolution can *easily* accomplish things which would be *impossibly* improbable by purely random means.

[shuckmaster]

If I understand you correctly, you're bragging that ignorance and crackpot charlatanism appears to be on a slight momentum roll!?