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

A Mantellisaurus Rampant, or Coo-Coo for Kukufeldia

On Thursday of last week, I wrote about the coat of arms for Maidstone, the small town in Kent where a quarry owned by W.H Bensted yielded important Iguanodon bones in 1834.


The Maidstone Slab. From wikimedia commons.

In the comments, Matt Martyniuk questioned whether those bones would still be considered Iguanodon. It was a good question, because Iguanodon happens to be one of those genera that is a taxonomic cluster... well, you know what I'm getting at. Check out the Iguanodon page at Wikipedia for a daunting list of putative Iguanodon species later reassigned to other genera and others currently considered dubious.

A paper published in the latest Zootaxa is another attempt at resolving the mess, reaching far back to teeth described by the father of Iguanodon, Gideon Algernon Mantell, in 1848. Andrew McDonald of the University of Pennsylvania with Paul Barrett and Sandra Chapman from the Natural History Museum in London have erected a new genus, Kukufeldia tilgatensis, after analyzing a collection of teeth assigned to Iguanodon by Mantell in 1848. The authors justify the new genera on the grounds that the teeth are sufficiently different from any other Iguanodon teeth (incidentally, Mantell never assigned his teeth to a species, only working on the level of the genus - that was how he rolled).

This naturally leads to the question: With the genus such a mess, what's the basis for comparison? Well, we're really lucky to have the three dozen Iguanodons discovered at the mine at Bernissart, Belgium in 1878; the skeletons provide a solid mark by which to measure other Iguanodons. Because of the quality of these specimens, Iguanodon bernissartensis was named the type species for the genus in 2000.

The teeth studied by McDonald et al originated from the same geological formation as the original teeth discovered by Mantell, and it's possible that those belonged to their Kukufeldia as well. There's so little to go on, they may never be positively tied to a valid species. However, Kukufeldia may be disputed in the near future. It comes from a geological formation called the Wealden supergroup, which was the subject of a recent overview by veteran Iguanodon researcher David Norman, also published in Zootaxa. Norman maintains that there are only two iguanodontians that can be named with any certainty from the Wealden's Upper Cretaceous deposits: Iguanodon bernissartensis and Mantellisaurus atherfieldensis, which was named by Greg Paul a few years ago. At the end of the abstract, Norman promises more work to come on providing further clarity to the genus.

So, you see why I called Matt a "sick, sick man" in response to his comment. Taxonomy would be a good candidate for an episode of "Dirty Jobs." I bet it would break Mike Rowe's spirit.

What of the Maidstone coat of arms? It's up in the air, but I'll hazard a guess. In the early nineties, David Norman reevaluated the Maidstone slab and noted that the dinosaur it most resembled was Iguanodon atherfieldensis (see page 234 of this volume). That species was the one which Greg Paul renamed Mantellisaurus atherfieldensis. As Norman supports Mantellisaurus in his latest writings, this looks to be a decent candidate for Maidstone's patron dinosaur. To revise the title of my original Maidstone post, the coat of arms features a Mantellisaurus rampant. I'm sure the fair citizens of Maidstone would find that most agreeable.

UPDATE: Check out Darren Naish's three-part series on Iguanodon at the SciAm Guest Blog. Part one is here.