Long in the Hoof

15 March 2008

Lower molar of a new Cretaceous mammal from India
from Prasad et. al 2007.

Behold: Kharmerungulatum vanvaleni – Van Valen’s “ungulate” from the Kharmer River!

Our picture of Mesozoic mammals has been paroxysmal. Fossils like
Repenomamus and Volaticotherium have hacked away at the stereotype of Mesozoic mammals as uniformly pitiful bits of dino-bait. Meanwhile molecular investigations of mammal phylogeny retrodict a Cretaceous diversification of most extant mammalian groups. The isolated molar shown above, presented in last year’s Science (Prasad et. al, 9 November 2007), adds a yet another tiny, curious wrinkle to the story.

The first thing to note is the absurd tininess of the tooth. It’s about 2.5 millimeters long, “half the size of an ant” as LiveScience notes. Or, .002 London bus equivalents. Next is the shape of the tooth: broad, and relatively sturdy with rounded cusps. This suggests that the animal was an herbivore. “We consider Kharmerungulatum to represent an early stage in the evolution of ungulates.”

Fair enough!


Prasad et al. 2007 – A Cretaceous Hoofed Mammal from India — Science 318 5852: 937 

4 Responses to “Long in the Hoof”

  1. Fair enough!

    I beg to differ. Leaving aside the question of ungulate monophyly, which is decidedly doubtful, Prasad et al. compared Kharmerungulatum to pitifully few taxa. The main reason for considering Kharmerungulatum an ungulate was similarities to Protungulatum, which according to the analysis of Wible et al. (2007) isn’t even a crown-group placental!

    Wible, J. R., G. W. Rougier, M. J. Novacek & R. J. Asher. 2007. Cretaceous eutherians and Laurasian origin for placental mammals near the K/T boundary. Nature 447: 1003-1006.

  2. Neil Says:

    Thanks Christopher. That half-assed closing comment was supposed to be tongue-in-cheek…but it wound up being hoof-in-mouth, or something. I’ve had this post sitting in the docket since the original paper came out, but since we’re still technically on strike I couldn’t flesh it out any more.

  3. Zach Miller Says:

    On strike? What’s that mean?

    Also, Chris (and Neil), tell me more about ungulate polyphyly! I was unaware that the monophylyl of Artiodactyla and Perissodactyla was even questioned!

  4. neil Says:

    Hey Zach…All I’m asking for is a written guarantee that when microecos material is syndicated on TBS or the CW or whatever, I will receive fair compensation. So far not a single network has returned my calls or e-mails…until then I’m afraid you all will have to be content with crappy repeats and unreleased ‘rarities’…

    Allowing for the inclusion of whales within (or very near to) artiodactyls, the two groups you mentioned are each probably monophyletic themselves, but together they probably don’t form a natural grouping to the exclusion of other mammals.

    Ergo the search for a ‘stem-ungulate’ (which is sort of what Prasad et al. are trying to suggest Kharmerungulatum is) is probably a wild snipe chase. And at any rate the paenungulates (manatees, elephants, aardvark and co.) almost certainly don’t belong with other ‘hoofed’ animals and may or may not be monophyletic themselves.

    Christopher is, of course, free to beg to differ with my assessment…on his knees!

    Ultimate ungulate has a nice summary.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s