…and this is a 
Indohyus
Category: Evolution • Fossils • Organisms • Science
Posted on: December 19, 2007 8:26 PM, by PZ Myers
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 back 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.
(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.
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.
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Comments
Amazing to think how things have changed in 6000 years.
Posted by: Bride of Shrek | December 19, 2007 8:42 PM
Carl Buell rules!
Posted by: Hank Fox | December 19, 2007 8:47 PM
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?
These are a sister group, right? Not ancestors to whales, but relatives to their ancestors.
Posted by: BaldApe | December 19, 2007 8:53 PM
Is this any relation to Diacodexis?
Posted by: Stanton | December 19, 2007 8:58 PM
blockquote> the bones are unusually dense and carry a particular ratio of radioactive isotopes that say that Indohyus spent a lot of time in the water
I don't have access to the paper from here, but I suspect that the authors analyzed stable isotopes (probably O-18)rather than radioactive ones. I don't think there any biologically relevant radioactive isotopes that would hang around long enough to be useful in this context.
Posted by: Tex | December 19, 2007 9:12 PM
#5,
You can use potassium/argon, uranium/lead, and rubidium strontium, among other such radioactive dacay dating schemes.
Take a look at the following link: http://www.agiweb.org/news/evolution/datingfossilrecord.html
One thing is that bones would have mineralized, and perhaps the potassium argon would be a useful dating method. I'm not aware of any radioactive calcium isotopes that would have half lives in such a relevant time period, but that's also a possibility.
Posted by: Helioprogenus | December 19, 2007 9:31 PM
It's not a matter of dating in this case, but of looking for traces of marine water vs. fresh water.
Posted by: Monado | December 19, 2007 9:41 PM
The skull looks right.
Cool to see another intermediate form.
Posted by: thadd | December 19, 2007 10:28 PM
You wacky evolutionists crack em up. First you tell us that bears turned into whales. Then when that is proved wrong, you tell us that you really meant hippos, not bears. Now that it's proved that the hippo story was a lie, you are trying to tell us that deer turned into whales. What's next? Are you going to tell us that ocelots or bats turned into whales?
When are you going to give up all this foolishness and admit what we Christians have known all along, that God created the whales in their present form on the fifth day with all the other fish?
Pastor Billy-Reuben
LandoverBaptist.net
Posted by: Pastor Billy-Reuben | December 19, 2007 11:17 PM
Very cool stuff, PZ. But what happened to the 'blogging on peer-reviewed research' icon? Just curious...
Also, comment #9 links to what appears to be a spoof site, so I'm guessing Billy-Reuben (and, no doubt, Cousin Heme O'Globin) is also a spoof.
Posted by: Scott Hatfield, OM | December 19, 2007 11:25 PM
skeleton looks a lot like pakicetus.
also:
"TWO MORE GAPS!"
Posted by: arachnophilia | December 19, 2007 11:28 PM
Billy,
The hippopotamus is, I believe, still the closest-known living relative of the whales. We're just uncovering more detail as to the evolutionary tree, that's all.
As for bears, that was just Darwin's hypothesis, and was never considered to be a conclusion from evidence. Just one possibility. It turned out to be wrong, of course, but then, most hypotheses do.
Posted by: Jason Dick | December 19, 2007 11:56 PM
Carl Buell... phew!
Might be worth saying, for the people who don't know him: C. Buell did a coupleof posts on his illustrations of whale evolution at his, alas now defunct, blog Olduvai George
An amazing illustrator.
Posted by: Arnaud | December 20, 2007 12:06 AM
Wow, thats really neat! Yet another reason why evolution will always be more interesting than any religious explanation, and why it will always be more beautiful.
Posted by: The Stone | December 20, 2007 12:06 AM
Just to address Billy's comment, one of the big things about this discovery, which both PZ and the original author point out, is that this skeleton, in showing features restricted to modern day whales and being a herbivore, really changes our understanding of whale evolution. The old theory behind whale development was based on the idea that the cetacean ancestors were coast-dwelling wolf-like creatures who, for whatever reason, came to rely more and more on fish for their diet until they eventually, over millions of years, made the switch to an aquatic life. This theory was based on the oldest cetacean and pre-cetacean skeletons that had been found for much of the 20th century, all of which were primarily aquatic and shared dental-traits with other fish eaters. By finding a land animal that's obviously a herbivore and that also shares a common cranial trait, the bulla, with all other previously discovered cetacean fossils, Thewissen has shown conclusively that this previous understanding is flawed and that predation developed after the cetaceans became aquatic.
You see, that's what separates science from religion; when scientists find evidence that is incontrovertible and contradicts their previous ideas, they change those ideas to take account of the new information. You see it as a weakness, but it's why you didn't die, strapped into an iron lung and unable to even move your chin, at the age of 12, or bleeding and pissing your life away from cholera at the age of 16. The ability to learn is science's greatest strength.
Posted by: Julian | December 20, 2007 12:19 AM
I don't see that in the paper. He specifically refers to the pakicetids as having teeth that, like the later cetaceans, appear to reflect a carnivorous diet. Indeed, his whole point is that the ancestral artiodactyl was already at least partially aquatic, and the change in diet came later in the lineages of the cetaceans and raoellids.
Posted by: Owlmirror | December 20, 2007 12:54 AM
That wacky flying spaghetti monster sure went to a lot of trouble to entertain us! Praise be!
Posted by: Marcus Ranum | December 20, 2007 1:09 AM
Pastor Billy writes:
First you tell us that bears turned into whales.
No, no, no... they had common ancestors. They didn't "turn into"...
Next you're gonna ask "with all the retarded baptists around, why are there still monkeys?"
Posted by: Marcus Ranum | December 20, 2007 1:18 AM
"Next you're gonna ask "with all the retarded baptists around, why are there still monkeys?""
It's the other way around. With monkeys, why are there still retarded baptists?
But really guys, Landover Baptist.
Posted by: Samnell | December 20, 2007 1:36 AM
PZ @ top: "... this pushes back our understanding of the ancestry of whales yet further back."
Ah, the two-backed beast.
Could we reduce the redundancy of this sentence a bit more reduced?
Posted by: Pyre | December 20, 2007 1:41 AM
These SUPPOSED FOSSILS were found in KASHMIR which is a song by the known DEVIL WORSHIPERS Lead Zepplen who use ANAPEST TO CORRUPT are youth and force them to SIN with PREMARITAL SEX and BESTIALITY!!! SATAN leaves his EVIL CLUES for all to see and the ATHIEST PZ MYERS knows only to well THIS TRUTH. JONAH was swallowed by THE WALE as THE BIBLE tells us in the WORDS OF GOD and WALES are GOD'S HOLY CREATION and survived the GREAT FLOOD on NOAH'S ARK. Why are their NO FOSSILS of a HALF RACOON HALF WALE PZ????!!! The INTELLGENCE OF GOD and his GREAT DESIGNS cannot be denied. AMEN!
Posted by: mayhempix | December 20, 2007 2:26 AM
Please stop. I really can't tell the difference any more between Landover-style parody and the fundie real thing^TM.
Posted by: AlanWCan | December 20, 2007 2:39 AM
"WALES are GOD'S HOLY CREATION"
The Welsh certainly agree. They call their own language "the language of Heaven".
But what does that have to do with cetaceans?
Posted by: Pyre | December 20, 2007 3:49 AM
And those in Wales certainly have more Brains than mayhempix seems to be displaying.
Posted by: Peter Ashby | December 20, 2007 4:02 AM
#9 Pastor Billy-Reuben:
Your ignorance is so blatant that I am uncertain whether you are just a parody or the real thing!
No-one ever claimed that whales descended from modern bears, hippo's or (in this case) deer!
Scientists found out that whales seemed RELATED to a range of creatures that are bear-LIKE (Mesonychids), then to pigs and hippos and -with this discovery- creatures that are deer-LIKE.
Rather than changing positions all the time this is actually REFINING the discoveries, because all these creature are (affiliated with) even-toed ungulates. Mesonychids are related to artiodactyls, hippos belong with pigs to an artiodactyl suborder (Suinae) and so does this newly discovered deer-LIKE creature.
So it all hangs together and confirms each other!
But I guess I am just casting pearls for pigs now...
Posted by: Fedor Steeman | December 20, 2007 5:24 AM
Everyone - go and look at Landover Baptist before commenting and save yourself an aneurysm. It's a parody site. Billy-Reuben, geddit?
The block caps guy, I'm not so sure about.
Posted by: NC Paul | December 20, 2007 5:44 AM