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.
Words of wisdom.
Bluster is not argument, jimbob.
Neither is deliberately misspelling a screen name, shrubot. Besides, you are hardly one to cast a bluster stone. Re-read your posts.
Your point was ridiculous. Stop taking things so personally.
Since I wasn't replying to you, what business is it of yours?
Your longevity argument is like the argument from a misinterpreted Bible passage. It has no weight.
Wasn't bragging on my longevity to impress you. Just making a point that I'm tired of his vitriolic tone. Just like I'm tired of yours. It's a pathetic minister who constantly puts others down in order to attempt to bolster his argument. BTW, I guess an apostate minister would know a lot about misinterpreting Bible passages.
Just read this thread. There is much there included pictures which will be easier for you to comprehend.
Ah, I didn't call you a troll. I said that if you were posting that man-from-ape cr@p (totally refuted on this and everyother evolution thread, you were either totally ignorant of evolutionary theory or you were just posting that cr@p to disrupt. Since you imply you are not the latter, you are just ignorant. Now you know better so don't post that cr@p again.
A lot of the scientific are religious and those are also calling the YEC creationists idiotic since the YEC often post FALSE SCIENCE.
Another "ignorant" or "disruptive" post. Where do you get these lies?
Did you know that your brain can't tell the difference between "yellow" light and the equivalent mixture of red and green light?
The two bands mentioned in the article or whatever.
Parts such as pump and motor do not actually compose a flagellum. It is a metaphor, not a literal meaning in this case. As a creationist, I am sure you have trouble separating the two, but that is not my problem. Go back and read the article you refused to read in the first place.
You should have pointed out that a lot of religious scientists think creationists' religion is nonsense, too.
An apostate creationist should respect his betters.
It's called "mutation". You might do well to actually study the mechanics of evolution before proclaiming yourself an expert.
Never said I was an expert, but I do wish you would tell me how precisly that mutation thing works because when ever I've heard or seen a mutation, it has died shortly after birth. With the rare carnival side show exceptions.
What lack of transitionals?
For instance, the transitionals between ape ancestors and man, whale and hippo...
It starts with a single-celled organism.
Which just happens to contain the entire genetic code needed to populate the earth...plants, people, animals... uh huh
An apostate creationist should respect his betters.
When I find one, I'll be sure to let him/her know.
Another "ignorant" or "disruptive" post. Where do you get these lies?
I go to evolutionist web sites and copy/paste them. I find it's a lot easier than making up lies.
Ah, I didn't call you a troll. I said that if you were posting that man-from-ape cr@p (totally refuted on this and everyother evolution thread, you were either totally ignorant of evolutionary theory or you were just posting that cr@p to disrupt. Since you imply you are not the latter, you are just ignorant. Now you know better so don't post that cr@p again.
From post #1656 Are you really so ignorant of evolutionary theory to believe that we evolved from apes or are you just a troll injecting the rediculous into the argument for disruption's sake?
I don't think liars need to tell me what I should or should not post.
I was looking for the </sarcasm> but then realized you were serious.
Your post of my previous post confirms the consistency of my posts. I did not call you a troll. I asked whether you were ignorant or a disruptive troll. Only one or the other would paste such cr@p.
I didn't tell you what you should or should not post. I said "Now you know better so don't post that cr@p again".
From your post # 1056:
Jesus Sent to Us! Jesus Crucified for Us! Jesus Died for us! Jesus Resurrected!-this is the GOOD NEWS!
For God sent his Son, who has always existed, to us to show us His sacrifice on the Cross. This act expunges our sins so that God can look at us as pure and holy, although we can never deserve this consideration. This is called God’s Grace, the unmerited favor.
We cannot earn this, but we are imputed with sinlessness or righteousness because of Jesus dying on the Cross. But this is still not enough to get us into Heaven. This may only be enough to get us to the Post Office. Jesus had to conquer death in His resurrection after 3 days in the tomb and ascend to Heaven. Then he came back and appeared to the apostles and disciples and many others so that they could believe in these events. It is only in the belief that Jesus is God’s Son, that he died, that he resurrected and that the testimony of those that saw Him alive after His death reinforces our belief that we can find Heaven. God gives us the directions to Heaven by his gift to us of these events. Then he leads us to Heaven by the gift of the Holy Spirit- all this is God’s Grace.
From your post #1729:
You should have pointed out that a lot of religious scientists think creationists' religion is nonsense, too.
So, what if a person has as the basis for his religion all that you mentioned in post #1056 concerning Christ and yet still believes in a young earth? (I do not personally believe in a young earth, but know and love some who do) Is their religion nonsense?
Maybe you want to reword. Do you meant to say that a persons religion support ONLY YE?
In that case, their religion may or may be nonsense, but that aspect of it is nonsense.
And, if they insist on bringing false science into the debate or using their religion as "fact" in the debate, that is a more than nonsense.
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