What’s that you say? No epipophyses in titanosaurs? Oh really?
February 6, 2015
This just in, from Zurriaguz and Powell’s (2015) hot-off-the-press paper describing the morphology and pneumatic features of the presacral column of the derived titanosaur Saltasaurus. (Thanks to Darren for bringing this paper to my attention.)
Now, as everyone knows, titanosaurs don’t have epipophyses. In fact, they’re the one major sauropod group where Matt has not observed them.
Look at the left postzygapophysis, at top left of this image. Doesn’t that look like there’s a distinct rounded eminence sticking out towards the camera?
No? Not convinced? All right, then, how about this?
This time, look at the right postzyg (again at top left in the image). Doesn’t that look like there are two separate bony structures up there separated by a notch? A postzygapophyseal facet below, and an epipophysis above? Right?
Huh? What’s that? Just damage, you say?
All right. Let’s bring out the smoking gun.
Again up at top left, we seem to have a clear case of a ventrally directed postzygapophyseal facet surmounted by a separate eminence which can only be an epipophysis. It even seems to be roughened for tendon attachment.
What does this mean? Only the same thing we said last time: The more we look for epipophyses, the more we find them. Amazing how often that turns out to be true of various things.
We seem to be headed towards the conclusion that epipophyses, while never ubiquitous, pop up in all sorts of places scattered all across the ornithodiran tree, encompassing birds, other theropods, sauropods, prosauropods, several groups of ornithischians, and both pterodactyloid and “rhamphorhynchoid” pterosaurs.
But what about outside Ornithodira?
Can we find epipophyses even out there, in the wilderness?
- Zurriaguz, Virginia, and Jaime Powell. 2015. New contributions to the
presacral osteology of Saltasaurus loricatus (Sauropoda, Titanosauria)
from the Upper Cretaceous of northern Argentina. Cretaceous Research