Pharyngula

Indohyus

We’ve got a splendid new analysis of a southeast Asian artiodactyl from the Thewissen lab that reveals that these little deer-like animals are a sister taxon to whales — so this pushes our understanding of the ancestry of whales yet further back. Carl Zimmer has already described the essentials — I’ll just show a few pictures of the fossils.

If you’re read Zimmer’s At the Water’s Edge, you already know that one of the key diagnostic features of cetaceans is the large auditory bulla at the bottom of the skull. It’s a distinctive bony capsule that contains the ear structures, and which also has a thick, medial lip called the involucrum. Here’s the skull of these fellows, with that bulla marked out for you. This feature was unique to the whales; now we have to include the raoellid artiodactyls.

i-470f939baa31a1469cb5fe7b64163c31-indohyus_skull.jpg
(click for larger image)

Oblique lateral view of skull RR 208 (a) and ventral view of skull RR 207 (b)

This is the whole skeleton. It doesn’t look very whale-like, does it? But the bones don’t lie — this is what the ancient ancestor of whales resembled. You can also see a Buell painting of this lovely animal.

i-f0a34f1a2c642d0c4b66061b14610c5c-indohyus.jpg
Hatched elements are reconstructed on the basis of related taxa.

Other revealing details: the bones are unusually dense and carry a particular ratio of isotopes that say that Indohyus spent a lot of time in the water — it was a wader that trotted about in the shallows. It was also an herbivore, so the fondness for an aquatic lifestyle came first, then carnivory.


Thewissen JGM, Cooper LN, Clementz MT, Bajpai S, Tiwari BN (2007) Whales originated from aquatic artiodactyls in the Eocene epoch of India. Nature 450:1190-1194.

Comments

  1. #1 David Marjanovi?, OM
    December 20, 2007

    I keep looking at the feet. Of course the enlarged middle toes are consistent with the artiodactyl link, but would they have had to revert to the more primitive form before becoming the flipper of a whale?

    No. Rodhocetus still had little hooves on some of its presumably webbed fingers and toes. What happened is that the whole hands and feet were enlarged.

    Diacodexis is close in being a basal artiodactyl. All of the earliest artiodactyls look more or less like this.

    Pigs and hippos were long thought to be close relatives, but both molecular and morphological studies now agree that they aren’t. Instead, the hippos are closer to the whales, and at least according to the molecular studies the ruminants are closer to both of the above than the pigs and even the camels are.

  2. #2 David Marjanovi?, OM
    December 20, 2007

    I keep looking at the feet. Of course the enlarged middle toes are consistent with the artiodactyl link, but would they have had to revert to the more primitive form before becoming the flipper of a whale?

    No. Rodhocetus still had little hooves on some of its presumably webbed fingers and toes. What happened is that the whole hands and feet were enlarged.

    Diacodexis is close in being a basal artiodactyl. All of the earliest artiodactyls look more or less like this.

    Pigs and hippos were long thought to be close relatives, but both molecular and morphological studies now agree that they aren’t. Instead, the hippos are closer to the whales, and at least according to the molecular studies the ruminants are closer to both of the above than the pigs and even the camels are.

  3. #3 David Marjanovi?, OM
    December 20, 2007

    He’d seen a display suggesting that whales were descended from “a dog-like creature”

    Back in those days, people really thought the whales were descended from carnivorous animals, if not even from Carnivora itself. Before we had good fossils of very early whales, and before 2001 we didn’t, there was a conflict between the genes, which put the whales next to the hippos, and the fossils — the most similar teeth to those of early whales are found in the carnivorous mesonychians, which are probably close relatives of Artiodactyla but still outside that group; and, of course, molecular phylogenetics only got started in the middle 1990s, and in those times they had quirks like putting the mice and rats outside a clade composed of the guinea pigs plus all other placental mammals, so it was entirely reasonable not to trust this unexpected result.

    The museum display in question was almost certainly older than that.

  4. #4 David Marjanovi?, OM
    December 20, 2007

    He’d seen a display suggesting that whales were descended from “a dog-like creature”

    Back in those days, people really thought the whales were descended from carnivorous animals, if not even from Carnivora itself. Before we had good fossils of very early whales, and before 2001 we didn’t, there was a conflict between the genes, which put the whales next to the hippos, and the fossils — the most similar teeth to those of early whales are found in the carnivorous mesonychians, which are probably close relatives of Artiodactyla but still outside that group; and, of course, molecular phylogenetics only got started in the middle 1990s, and in those times they had quirks like putting the mice and rats outside a clade composed of the guinea pigs plus all other placental mammals, so it was entirely reasonable not to trust this unexpected result.

    The museum display in question was almost certainly older than that.

  5. #5 David Marjanovi?, OM
    December 20, 2007

    “They” in my second-to-last sentence are the molecular phylogenies older than 2001 (and, by default, younger than 1993 or so).

  6. #6 David Marjanovi?, OM
    December 20, 2007

    “They” in my second-to-last sentence are the molecular phylogenies older than 2001 (and, by default, younger than 1993 or so).

  7. #7 Jackie
    January 3, 2009

    Lorne: “Ya gotta love it. Every few months a new transitional fossil being reported in the news. Sure must make being a creazytionist really tough.”

    Actually, for those with no taste for the Darwinian Kool-Aid, each time some fragmentary fossil is ballyhooed as the latest discovery of a “transitional” form, it’s hard to keep from falling out of the chair laughing. Among other things, the confident assertions Darwinists make on the basis of the flimsiest of fossil evidence brings the following to my mind:

    “Contrary to what most scientists write, the fossil record does not support the Darwinian theory of evolution, because it is this theory…which we use to interpret the fossil record. By doing so, we are guilty of circular reasoning if we then say the fossil record supports this theory.” – Ronald R. West, “Paleontology and Uniformitarianism,” Compass 45 (May 1968): 216

    I have to wonder why the Darwinian faithful fail to realize that a neo-Darwinian hypothesis (such as land mammal to whale evolution) is not confirmed by interpreting the fossil record through the filter of neo-Darwinism. When the theory is used to justify an interpretation of the fossil record (as it routinely is), the interpretation cannot then be used to justify the theory. Logic is apparently not a strong suit in the Darwinian camp.

  8. #8 Owlmirror
    January 3, 2009

    Anti-evolutionists persist in not understanding science.

    “Contrary to what most scientists write, ballistics does not support the Newtonian theory of gravitation, because it is this theory…which we use to interpret ballistics. By doing so, we are guilty of circular reasoning if we then say ballistics supports this theory.”

    “Contrary to what most scientists write, illness does not support the Pasteur theory of germs, because it is this theory…which we use to interpret illness. By doing so, we are guilty of circular reasoning if we then say illness supports this theory.”

    I have to wonder why the Darwinian faithful fail to realize that a neo-Darwinian hypothesis (such as land mammal to whale evolution) is not confirmed by interpreting the fossil record through the filter of neo-Darwinism. When the theory is used to justify an interpretation of the fossil record (as it routinely is), the interpretation cannot then be used to justify the theory. Logic is apparently not a strong suit in the Darwinian camp.

    Stupid fuckwittery is apparently the strong suit of the anti-evolutionary camp.

  9. #9 Sastra
    January 3, 2009

    Jackie #56 wrote:

    I have to wonder why the Darwinian faithful fail to realize that a neo-Darwinian hypothesis (such as land mammal to whale evolution) is not confirmed by interpreting the fossil record through the filter of neo-Darwinism.

    When a theory makes a successful prediction, there is no need for it to be viewed through any filter but the common ground of nature and observation of nature.

    It’s as if creationists consider all scientific theories to be matters of aesthetic taste.

  10. #10 KnockGoats
    January 3, 2009

    Jackie,
    As is typical of lying creobot morons, you find a very old thread to deposit your stale leavings on, hoping no-one will bother to answer so you can tell yourself you’ve “won”. Tough luck. Could you really not find anything better to refer to than a 40-year old article? West is, of course, wrong. Modern evolutionary theory predicts the kind of fossil sequence that we will find if we are fortunate (fossilisation is a rare event), and more important, what should not be found – for example, fossil rabbits in the Precambrian would immediately call the entire theory into question. The relative dating of the strata in which vertebrate fossils are found was worked out before Darwin published. Absolute dates for many have since been provided by radioactive dating methods. Modern evolutionary theory predicts that as we go back through older strata, the fossils should be more and more different from living organisms – and they are. It predicts that for mammals that now live in the sea but show anatomical evidence of relationships to land mammals, we can hope to find fossils showing the transitional stages of adaptation to life in the sea. In the case of whales, we now have a wonderful sequence of such fossils. Before these were found, creobots like you routinely sneered that their absence disproved evolution. Your behaviour is the height of dishonesty.

    If modern evolutionary theory relied solely on the fossil record, West might just have a point – although not a very strong one. It does not. It integrates and explains observations from the whole of biology: morphology, physiology, behaviour, developmental biology, biogeography, ecology, genetics and more, as well as paleontology. Your creationist bilge explains – nothing. It integrates – nothing. It predicts – nothing. It has produced no research. It never will. It is a tissue of lies.

  11. #11 Danio
    January 3, 2009

    Dear me, Jackie, what a vulgar display of ignorance that was. I don’t even need to ask whether you’ve read Zimmer’s book, or the primary literature discussed in the original blog post. The fact that you are using a 40 year old quote to attempt to deride recent, scientific discoveries says a lot about who is actually hitting the Kool-aid, although, in fairness, 40 year old literature is somewhat of an improvement over the 2000 year old material you guys (including, I suspect, Ronald West himself) usually reference.

    Although I’m unfamiliar with the publication “Compass” (and, shockingly, a search of PubMed turns up no such journal), a quick google shows that quote, with the same attribution, all over the creationist web pages. Color me unsurprised at your incapacity for independent thought. I strongly urge you to peruse some additional, current research before continuing your pronouncements on how deficient *our* logic is.

  12. #12 Nerd of Redhead
    January 3, 2009

    At least this creobot gives a journal citation. But rather than to the primary scientific literature, it appears to be a travel magazine. Science is only refuted by more science. An opinion piece from a travel magazine isn’t even worth the paper it is printed on. Sigh. I’ll give him a point for the citation, but otherwise just the staple ideas already disproved by real science. Fail, F+.

The site is currently under maintenance and will be back shortly. New comments have been disabled during this time, please check back soon.