Saturday, April 05, 2008

Effigia: The Jar-Jar Crurotarsian


I don't mean to insult the coolest example of convergent evolution since the marsupial mole, but it's tough to not get a kick in when Effigia's species name is okeefae. It sounds like something you'd hear while watching The Phantom Menace, as in "Ooh! Meesah like Effigia okeefae!"

At any rate, Effigia is another subject for the Archosauria art show. I imagine you're all familar with Carl Buell's wonderful reconstruction. My goal was to make the little bugger look a bit more...you know...crurotarsian. It's closest relatives were big-bodied, scute-covered, bony-armored crocodilian critters. It did, however, famously converge on theropod dinosaurs. While it seems to have lost its bony armor, I'm sure it retained some keratinous covering. Bizarrely, Effigia lost its teeth and developed an ornithomimid-like beak--it was probably an herbivore. I think it's tiny little arms are ridiculous-looking, but they were fun to draw.

I'm not entirely sure how the ankles worked. Effigia did not develop an ornithodiran ankle structure--it retained the "crocodile-normal" ankle which relies on a pully structure to move the ankle with the leg, so I wonder how flexible the ankle was on its own. The animal clearly walked bipedally (look at those tiny forelimbs) but how fast it could walk (or run) is puzzling to me.
This drawing is basically taken from Nesbitt's 2007 description, so the proportions are right on the money. The length of the femur is unknown, as is the number of cervicals. I shortened the neck but stayed close to the description's proposed femur length. My big question is what kind of integument Effigia had. I don't think it had crocodilian plating, but I doubt it was entirely free of scutes and plates, too. I'd like to reach a comfortable middle ground, if for nothing else than to emphasize in the show that this is not a dinosaur, but converged on dinosaurs.

As always, comments and questions are more than welcome.

3 comments:

Nathan said...

When did this thing live?

Jerry D. Harris said...

It sounds like something you'd hear while watching The Phantom Menace, as in "Ooh! Meesah like Effigia okeefae!"

...except that it's pronounced "oh-KEE-fee," not "oh-KEE-fay."

Zach Miller said...

Little bugger's from the Late Triassic, Nathan. In fact, it's known from Ghost Ranch Quarry, which is famous for its large quantities of Coelophysis. The two lived side-by-side!