Come On Shake Your Body Baby, Do the Concavenator

That's a Miami Sound Machine reference. I usually footnote the odd references in my post titles, but I feel like this post will be much more fun if you have that song in your head. If you're having trouble summoning the tune - or if you sadly aren't familiar with the aural wizardry of the Sound Machine - here's the video. If anyone would be able to deal with the burden of three extra syllables being added to a song, Gloria Estefan would be the woman. Play it and read.



I am a little late to the Concavenator party, but I'm usually late to social functions in off-line life, so it's not stressing me too much. In case you haven't heard yet, Concavenator is a very cool, weird early Cretaceous theropod from Spain. Described in Nature by Francisco Ortega, Fernando Escaso, and José L. Sanz, it's the second strange theropod described in the last few weeks, and like Balaur, it's going to be the subject of debate for a while. Judging by its presence on the blogosphere and the conversation surrounding it on the Dinosaur Mailing List, it's making a much bigger splash than the island-dwelling dromaeosaur did.

The reason for this is probably its hump. Its hump and its possibly feathered forelimbs. Mostly though, the hump. People seem to love the hump.

Concavenator corcovatus by Raúl Martin. From the Nature paper.

Concavenator possessed elongated neural spines - those are the vertical protrusions on top of its vertebrae - right above the hips. This isn't the sort of sail that Spinosaurus would have had on its back; rather, it's more like a "fin," tying nicely into the fact that Concavenator was a carcharodontosaurid (that's seven syllables, if you weren't counting), the "shark tooth" relatives of Allosaurus who grew to enormous sizes in the Cretaceous before being replaced by giant tyrannosaurs and mid-size abelisaurs. It would have made for an odd-looking theropod, but at this point, ornamentation like this isn't shocking.

The really big news here is that Concavenator may have had quills or feathers on its arms. There is a line of bumps on its ulna - one of its longer arm bones - which look like the anchors for long flight feathers in modern birds, so the authors of the paper describing Concavenator propose that it had some sort of feathers or quills on its arms. This adds evidence to the idea that feathery, quilly, downy, filamentous body covering may have been a more basic trait of the dinosaurs than imagined. The image of dinosaurs as scaly beasts has been dead for a long time, of course, with multiple discoveries of skin and feather impressions. Ornithischians with quill-like features have been found, and the theropod clade known as the coleurosaurs include many feathered examples, and eventually spawned the modern birds. But carcharodontosaurids like Concavenator are carnosaurs (that's five hard C's, if you weren't counting), the sister clade to the coleurosaurs. It suggests that even earlier theropods could grow this kind of integument. So, too, may have the earliest dinosaurs. It's an open question, but daring paleoartists have some plausible grounding for clothing all sorts of dinosaurs in quills and feathery garments.

Dissenting voices have arisen in the days since the paper was published, proposing that the bumps may better be explained as being the line where muscle attached to the bone. It will just take more analysis, and hopefully some new, similar, dinosaurs to be found. I absolutely relish good back-and-forths like this in paleontology; while the argument itself may not be settled soon, I always come out of it with some new knowledge about evolution or anatomy.

Just don't get too used to saying Concavenator. It looks like this beast has already been named, from an earlier discovery of those hump-forming vertebrae. That name is Becklespinax.

More on Concavenator, er... Becklespinax:

Not Exactly Rocket Science
Dinosaur Tracking
Science Today
Theropoda (english speakers will want to use Google translate)
More on the quill knobs: Dots in Deep Time, Tetrapod Zoology.
More on Becklespinax: Tetrapod Zoology also covers this in detail; the Theropod Database Blog's first and second posts.
Artistic reconstructions: Brett Booth, Tricia Arnold, Camila Alli Chair, Nobu Tamura