Posted on 02/08/2005 3:50:43 AM PST by PatrickHenry
A group of four-footed mammals that flourished worldwide for 40 million years and then died out in the ice ages is the missing link between the whale and its not-so-obvious nearest relative, the hippopotamus.
The conclusion by University of California, Berkeley, post-doctoral fellow Jean-Renaud Boisserie and his French colleagues finally puts to rest the long-standing notion that the hippo is actually related to the pig or to its close relative, the South American peccary. In doing so, the finding reconciles the fossil record with the 20-year-old claim that molecular evidence points to the whale as the closest relative of the hippo.
"The problem with hippos is, if you look at the general shape of the animal it could be related to horses, as the ancient Greeks thought, or pigs, as modern scientists thought, while molecular phylogeny shows a close relationship with whales," said Boisserie. "But cetaceans – whales, porpoises and dolphins – don't look anything like hippos. There is a 40-million-year gap between fossils of early cetaceans and early hippos."
In a paper appearing this week in the Online Early Edition of the Proceedings of the National Academy of Sciences, Boisserie and colleagues Michel Brunet and Fabrice Lihoreau fill in this gap by proposing that whales and hippos had a common water-loving ancestor 50 to 60 million years ago that evolved and split into two groups: the early cetaceans, which eventually spurned land altogether and became totally aquatic; and a large and diverse group of four-legged beasts called anthracotheres. The pig-like anthracotheres, which blossomed over a 40-million-year period into at least 37 distinct genera on all continents except Oceania and South America, died out less than 2 and a half million years ago, leaving only one descendent: the hippopotamus.
This proposal places whales squarely within the large group of cloven-hoofed mammals (even-toed ungulates) known collectively as the Artiodactyla – the group that includes cows, pigs, sheep, antelopes, camels, giraffes and most of the large land animals. Rather than separating whales from the rest of the mammals, the new study supports a 1997 proposal to place the legless whales and dolphins together with the cloven-hoofed mammals in a group named Cetartiodactyla.
"Our study shows that these groups are not as unrelated as thought by morphologists," Boisserie said, referring to scientists who classify organisms based on their physical characteristics or morphology. "Cetaceans are artiodactyls, but very derived artiodactyls."
The origin of hippos has been debated vociferously for nearly 200 years, ever since the animals were rediscovered by pioneering French paleontologist Georges Cuvier and others. Their conclusion that hippos are closely related to pigs and peccaries was based primarily on their interpretation of the ridges on the molars of these species, Boisserie said.
"In this particular case, you can't really rely on the dentition, however," Boisserie said. "Teeth are the best preserved and most numerous fossils, and analysis of teeth is very important in paleontology, but they are subject to lots of environmental processes and can quickly adapt to the outside world. So, most characteristics are not dependable indications of relationships between major groups of mammals. Teeth are not as reliable as people thought."
As scientists found more fossils of early hippos and anthracotheres, a competing hypothesis roiled the waters: that hippos are descendents of the anthracotheres.
All this was thrown into disarray in 1985 when UC Berkeley's Vincent Sarich, a pioneer of the field of molecular evolution and now a professor emeritus of anthropology, analyzed blood proteins and saw a close relationship between hippos and whales. A subsequent analysis of mitochondrial, nuclear and ribosomal DNA only solidified this relationship.
Though most biologists now agree that whales and hippos are first cousins, they continue to clash over how whales and hippos are related, and where they belong within the even-toed ungulates, the artiodactyls. A major roadblock to linking whales with hippos was the lack of any fossils that appeared intermediate between the two. In fact, it was a bit embarrassing for paleontologists because the claimed link between the two would mean that one of the major radiations of mammals – the one that led to cetaceans, which represent the most successful re-adaptation to life in water – had an origin deeply nested within the artiodactyls, and that morphologists had failed to recognize it.
This new analysis finally brings the fossil evidence into accord with the molecular data, showing that whales and hippos indeed are one another's closest relatives.
"This work provides another important step for the reconciliation between molecular- and morphology-based phylogenies, and indicates new tracks for research on emergence of cetaceans," Boisserie said.
Boisserie became a hippo specialist while digging with Brunet for early human ancestors in the African republic of Chad. Most hominid fossils earlier than about 2 million years ago are found in association with hippo fossils, implying that they lived in the same biotopes and that hippos later became a source of food for our distant ancestors. Hippos first developed in Africa 16 million years ago and exploded in number around 8 million years ago, Boisserie said.
Now a post-doctoral fellow in the Human Evolution Research Center run by integrative biology professor Tim White at UC Berkeley, Boisserie decided to attempt a resolution of the conflict between the molecular data and the fossil record. New whale fossils discovered in Pakistan in 2001, some of which have limb characteristics similar to artiodactyls, drew a more certain link between whales and artiodactyls. Boisserie and his colleagues conducted a phylogenetic analysis of new and previous hippo, whale and anthracothere fossils and were able to argue persuasively that anthracotheres are the missing link between hippos and cetaceans.
While the common ancestor of cetaceans and anthracotheres probably wasn't fully aquatic, it likely lived around water, he said. And while many anthracotheres appear to have been adapted to life in water, all of the youngest fossils of anthracotheres, hippos and cetaceans are aquatic or semi-aquatic.
"Our study is the most complete to date, including lots of different taxa and a lot of new characteristics," Boisserie said. "Our results are very robust and a good alternative to our findings is still to be formulated."
Brunet is associated with the Laboratoire de Géobiologie, Biochronologie et Paléontologie Humaine at the Université de Poitiers and with the Collège de France in Paris. Lihoreau is a post-doctoral fellow in the Département de Paléontologie of the Université de N'Djaména in Chad.
The work was supported in part by the Mission Paléoanthropologique Franco-Tchadienne, which is co-directed by Brunet and Patrick Vignaud of the Université de Poitiers, and in part by funds to Boisserie from the Fondation Fyssen, the French Ministère des Affaires Etrangères and the National Science Foundation's Revealing Hominid Origins Initiative, which is co-directed by Tim White and Clark Howell of UC Berkeley.
developed GILLS???
oh, my... I cannot believe you said that.
please, find any cetatean with gills.
phytoplankton, IIRC
"It is to Professor Wilder-Smith that I owe the scientific falsification of evolutionary theory, which had become the scientific concretion of Hegelian dialectics as the alternative to metaphysics and theology. Wilder-Smith was the first and only person to have the courage to refute evolutionary theory as a whole on a principal level. In the meantime there are a number of renowned critics of single aspects of evolutionary theory. But nobody has dared attack or question evolutionary theory as such outside of the narrow confines of their own speciality. This is because no philosopher or scientist has identified and recognized the diabolic perversion of the substitution of principles: development of the spirit out of nature at the expense of individual particularities -- instead of the incarnation of the spirit for the redemption of persons enslaved by sin." (Professor Dr. Alma von Stockhause, Professor of Philosophy, University of Freiburg i.Br., Germany)
By the way, are you going to say that this man is not a legitimate scientist?
So, you are bringing in the same stupid strawman that creationists have been lying about for years. Give us a break and learn some biology.
Same argument that evolutionists have been lying about for years is that the origin of life has nothing to do with evolution, when it has everything to do with the origin of life. I don't know a lot about biology, but I know a lot about probabilities and statistics. Which I might point out is where evolutionists squeal like stuck pigs because they cannot refute the numbers. So they, like you revert to ad hom attacks.
Which brings me to another point. What kind of minister are you that allows you to be consistantly rude and obnoxious? Maybe you should be the one to give "us" a break and learn some manners.
"I am given to understand that the principal absolute requirement for dividing specimens into different species is the capacity to interbreed and produce fertile offspring. If they cannot produce viable offspring, they are different species. If they can, they are the same species, though possibly of breeds having radical morphological differences."
You are in the main correct. The main definition is two populations that cannot interbreed. There are caveats to this. First, it is two populations that don't interbreed in the wild. So, sometimes two populations that could interbreed, like Darwin's finches but don't , because they are geographically, ecologically or unwilling to because of color displays etc. (Sometimes, during drought or other
environmental change, two of the finch species come back together).
Second, sexually reproducing organisms go by the above. Asexually reproducing organisms are more difficult to define. It is clear that once something is significantly different in genetic characteristics it is a different species, but there will always be arguments, especially among closely related asexual forms.
Example: If a bacteria evolves into a new population resistant to a new antibiotic, is it a new species? It could be argued either way. However, if a bacteria evolves enough to produce different symptoms, it definitely would be classified as a new species.
Since species is the lowest difference and the only one that really matters in evolution, the change does not have to be very much to qualify as being a new species. Most speciation determinations between closely related beetles or nematodes, for instance, take a great deal of technical knowledge and expertise.
...humongous snip...
Summary: Species with similar morphologies have similar DNA structures (said with baited breath as if this is somehow an earth-shattering revelation.) Species with dissimilar morphologies have dissimilar DNA structures (again said with baited breath).
Translation: The gradual increase of dissimilarity in DNA among species with increasingly dissimilar morphologies conclusively proves common descent.
Logic professor: Let me introduce you to the term Circular Reasoning.
I tried to increase that knowledge. Even today on this thread their is evidence of that; and the evidence was thrown back in our face. The guy said he didn't believe that gravity held the moon in orbit with the earth. That is why my contempt grows. I had no contempt till I started seeing all the nuts on FR.
BTW, he also said Tesla had "free-energy" machine that big-money squashed.
Fine, just give me the name of the animal that is at the joint where the two branches meet. It's not listed on the tree. An alleged ancestor of the hippo is listed. An alleged ancestor of the whale is listed. But what is the name of the ancestor of both?
Or is that another yet to be discovered missing link?
"Same argument that evolutionists have been lying about for years is that the origin of life has nothing to do with evolution, when it has everything to do with the origin of life. I don't know a lot about biology,"
The origin of life has nothing to do with evolution. AIG and ICR and all the other charlatans introduced it to argue against evolution, since they have no actual science on their side.
You don't know a lot about biology.
What you perceive as rudeness is just a minister trying to get you away from the road to apostasy.
A basic difference. Creationists use false science.
No. And I don't enjoy being lied to.
thank you.
We would be able to see "hot" spots so we wouldn't burn ourselves. Not to mention a million other frequencies the eye doesn't detect.
No, it isn't. Only creationists make that misrepresentation.
one note on wolves - I saw a wolf running loose in the wild about two months ago here in Brooks County, GA.
Not a wolf-like dog, NOT a Coyote.
WOLF.
I think someone may have lost/loosed an illegal pet.
I hope it does well.
I don't love to call anyone a liar but I point out when they bear false witness; as you just did.
Common descent has never been challenged by any evidence, not even in weird creatures found in the ocean trenches. It would be quite surprising to find any "ordinary" creature that doesn't fit.
I have never seen a wolf in the wild, except on nature films. If it was a pet, the wolf will probably have some problems. But in many areas of the world, domesticated dogs run in wild packs and do quite well until the authorities shoot them.
In some areas, wolves are being restocked. Do you live in the northern forested area of Ga. I loved Lake Lanier.
I can't tell you how much contempt I have for creationists. If a little comes through TOUGH!
Did you notice on my personal page that I have a Dr. in Ministry and direct a homeless ministry in the inner city? So don't accuse me of hating the guy I work for.
I remember reading in my Bible that Jesus said that we show how much we love Him by the love we show others.
You are a very odd minister.
http://www.answersingenesis.org/pbs_nova/0924ep1.asp
You'll have to scroll down to the section that starts "Is there bad design?" Here are excerpts:
The retina can detect a single photon of light, and it's impossible to improve on this sensitivity! More than that, it has a dynamic range of 10 billion (1010) to one; that is, it will still work well in an intensity of 10 billion photons.
Another amazing design feature of the retina is the signal processing that occurs even before the information is transmitted to the brain, in the retinal layers between the ganglion cells and the photoreceptors.
The idea that the eye is wired backward comes from a lack of knowledge of eye function and anatomy.
He explained that the nerves could not go behind the eye, because that space is reserved for the choroid, which provides the rich blood supply needed for the very metabolically active retinal pigment epithelium (RPE). This is necessary to regenerate the photoreceptors, and to absorb excess heat. So it is necessary for the nerves to go in front instead. The claim on the program that they interfere with the image is blatantly false, because the nerves are virtually transparent because of their small size and also having about the same refractive index as the surrounding vitreous humour. In fact, what limits the eye's resolution is the diffraction of light waves at the pupil (proportional to the wavelength and inversely proportional to the pupil's size); so alleged improvements of the retina would make no difference.
It's important to note that the 'superior' design of Miller with the (virtually transparent) nerves behind the photoreceptors would require either:
See also the detailed response by the ophthalmologist Peter Gurney to the question Is the inverted retina really 'bad design'? This article addresses the claim that the blind spot is bad design, by pointing out that the blind spot occupies only 0.25% of the visual field, and is far (15 degrees) from the visual axis so the visual acuity of the region is only about 15% of the foveola, the most sensitive area of the retina right on the visual axis. So the alleged defect is only theoretical, not practical. The blind spot is not considered handicap enough to stop a one-eyed person from driving a private motor vehicle. The main problem with only one eye is the lack of stereoscopic vision.
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