A few years ago, I read a couple of essays by Stephen Jay Gould that dealt with the ancestry of whales. There seemed to be a fairly sound sequence that derived them from the mesonychids, a group of large bodied, large headed early carnivorous mammals (but not Carnivores in the taxonomic sense). This derivation was mentioned in the largest mammalian carnivore thread.
I recently saw some material, but with very little detail, that suggested that this derivation was incorrect, suggesting instead an ancestry close to the artiodactyls (pigs, camels, and ruminants). Unfortunately it was a very popularized article, without much detail, and I’ve never found anything else on it.
Does anyone have the Straight Dope on what present theory is? I’d thought of asking it in that thread but figured it was an unnecessary hijack, and deserved its own thread.
According to this, fossil evidence would place them deriving from mesochynids. Molecular evidence supports artiodactyls, most closely being related to hippos.
Sounds like the work of University of Michigan professor Philip D. Gingerich:
Indeed I remember Eddie jumping around on MTV in the '80s singing “Whales evolved from mesonychid condylarths, I hypothesize it’s 'cause of their teeth, yeh!”
Scientific American had an article on whale ancestry about a year back, where they supported the ruminant hypothesis. I don’t remember too many details, though.
The present theory is that Artiodactyls are the closest living relatives to the whales (that is, they are sister groups). This is mentioned briefly here. More information (indlusing references to primary literature) can be found here (lots of information there). From one of the articles at that site:
I think I also have access to a 2001 article from Nature which mentions the new Pakicetid find and its implications. Unfortunately, I don’t have access to it here, and will have to wait until I get home to check it.
And here is an old SciAm article (possibly the one referred to by Chronos?) on the subject. And another (which references the aforementioned Nature article), though this one doesn’t display properly in IE for some reason (stupid advertisements…).
Trivia note: The previous prevailing hypothesis (i.e. their relationship to the mesonychids) that is being replaced by the new Artiodactyl hypothesis is the work of my wife’s father, the “Van Valen” referenced in jjimm’s quote. It was a rather famously compelling bit of cladistic extrapolation at the time, and it’s rather sad to see it fading away in favor of the alternate DNA-based explanation.
Google “Van Valen” + cetacean for the background on what at the time was a groundbreaking hypothesis.
