Thursday, September 24, 2009

The Near-Bird Cometh

Above: New specimen of Anchiornis and skeletal showing feather proportions, from Hu et al. 2009. Click to embiggen.

If you've been carefully combing Dave Hone's blog for the last nine months or so (and who hasn't been?), you'll know that the initial reports on headless fossil of an interestingly bird-like supposed avialan named Anchiornis were just a warning shot. Dave reported in December of last year that protobird fans could look forward to several more complete specimens that had been recovered and not yet described. Well, it looks like the first of these is pending: J. Brougham over at Wikipedia has published a few details and a full cite from the upcoming October 1 issue of Nature, which contains the description of a nearly complete specimen preserving such cool details as a complete skull, Microraptor-style hind wings and head crest, and a phylogenetic anlysis that finds Anchiornis is in fact a basal, mid-late Jurassic troodontid (!), totally stealing Scott Hartman's thunder. If this is the case, that is, if Anchiornis can actually be demonstrated as a troodont (or even just non-dromaeosaurid) with large airfoils on the hind legs, the argument that all deinonychosaurs or even all birds went through a gliding tetrapteryx stage and are secondarily flightless to some degree just got pretty darn rock solid. Greg Paul, throw yourself a party, and set a place for William Beebe.

Being a protobird fan myself, this prompted me to immediately go to the nature.com online preprint section and start clicking refresh faster than you can whip a ram at Brewfest. Needless to say I was dissapointed and will have to start hounding J. about the paper until something pops up on the DML to whet my appetite for photos so I can get started drawing this thing. More to come one I have a chance to read the paper and collect some goss!

UPDATE:
Just been informed that not only is this on Nature's front page, but the pdf appears to be free? Or is it because I'm logged in?

Thursday, September 17, 2009

Raptorex update

Above: Recon of Raptorex by Todd Marshall, from CBC News.

Quick taxonomic update: Having just gotten the paper, I can comment that Bill Parker's concerns over the name Raptorex kriegsteini (see previous post), echoed on the DML, are based on misrepresentation of the issue by the newspaper reports. At least one news story said that Kriegstein named the species after his parents, so by ICZN rules the species name needs to be R. kriegsteinorum (-orum being the correct suffix for a name honoring multiple people). However, the paper explicitly states that the species is named only for Roman Kriegstein, so the current name is correct. For the record, here's the entire etymology section from Sereno et al. 2009:

Etymology: raptor, plunderer (Greek); rex, king (Greek); kriegsteini, after Roman Kriegstein, in whose honor the specimen was secured for scientific study.

Also, the paper makes clear that, unlike I speculated before, Guanlong, Dilong and friends are still recovered as tyrannosauroids in the paper's cladogram, though more basal than Raptorex.

Raptorex. For serious, that's a real dinosaur now.

Above: Paul Sereno with a model and skull cast of Raptorex, possibly the most ridiculously named dinosaur of all time. Photo from Chicago Tribune by Nancy Stone.

Headline: DeviantArtist Honoured with Dinosaur Name

Well not really, but surely raptorex must be stoked that his (let's face it), fun but pretty ridiculous username is now the name of a real life dinosaur, Raptorex kriegsteini.

The mini-tyrannosaur is from the Yixian ash beds (not the more famous lake sediments that preserve feathers), and is a bit improbable in other ways than its name. It looks like a mini-Tarbosaurus, with short, two-fingered hands and long, running legs, all things expected from a juvenile tyrannosaurid, rather than a (supposed) primitive tyrannosauroid like Dilong or Guanlong. I wonder if this has implications for their position as basal tyrannosaurs--the paper, supposedly released in the online edition of Science today, is nowhere to be found, for my part.

Raptorex also has a sordid past. Apparently, the fossil was smuggled out of China and sold at (where else) the Tuscon fossil show to a private collector for tens of thousands of dollars. The collector, ophthalmologist Henry Kriegstein (whose family name is honored in the specific name of the new dino), had specialists in Utah prep it out of its matrix so he could mount it in his Massachusetts living room. Upon discovering the specimen was not a juvi tarb as advertised, but rather a full-grown individual, Paul Sereno (so that explains the name!) was called in for further advice, and recognized it as an important discovery. Kriegstein soon agreed to relinquish his purchase to science (with a bonus in the form of naming rights, of course. At least he wasn't a big Bambi fan).

In a bit of taxonomic goss, Bill Parker over at Chinleana notes that, as Kriegstein technically named the genus for his parents, not himself (which is frowned upon), the ICZN mandates that the species name needs to be emended to kriegsteinorum, so watch for that change in the future, likely published by George Olshevsky or a similar stickler for proper Latin.

Here's a video with Sereno discussing the new find:

And, of course, Jack Horner has weighed in. In an email to Wired.com, Horner explained that he thinks the small, fleet-footed Raptorex, because it has the same body plan as larger tyrannosaurs, somehow proves that tyrannosaurs evolved into pure scavengers early on, and that the authors are jumping to conclusions in thinking that long, speed-designed legs somehow imply "predator." Keep on keepin' on, Horner.

Read more here, and keep watching for more goss!

Tuesday, September 8, 2009

Oh Giraffatitan, where art thou?

Above: Skull of Brachiosaurus altithorax (right, from Carpenter & Tidwell, 1998) and "B." brancai (left, by Gunner Rias, licensed).

A curious bit of goss, and potential drama?, teased out Mike Taylor and crew at SV-POW.

In recent posts about a new brachiosaurid announced last week, Qiaowanlong (or is it a brachiosaurid? See SV-POW for in-depth coverage), Mike Taylor consistently reffers to the genus "Brachiosaurus" brancai.

The goss stems form use of the quotes. As we all know, when discussing scientific names, the genus and species are always put in italics. The exception to this are nomina nuda, which are names not properly described or coined. Another exception is when a genus and species combo is found to be invalid for whatever reason. For example, the name Ingenia, for an oviraptorid, is preoccupied and has not yet been renamed. But the species name yanshini is still valid. So, when we talk about this species, we might write it as "Ingenia" yanshini to indicate that the genus name is going to change.

Similarly, this same notation is used for species previously assigned to one genus but are no longer considered related to that genus' type, and are pending reclassification under a new genus name. For example, the species "Dilophosaurus" sinensis is probably not closely related to Dilophosaurus wetherilli, so it gets quotes until a replacement name is chosen. This is also the current situation with "Brachiosaurus" brancai. Many people have suspected that this African sauropod is not the closest relative of the North american type species, Brachiosaurus altithorax, given that a B. altithorax skull has been identified that differs from the African species (see photos above), among other differences in skeletal shape and proportion.

So what's wrong with using quotes when talking about "B." brancai? The African version has already been given a new name! In a 1988 paper, Greg Paul coined the name Giraffatitan for a distinct "subgenus" containing the African species. This was later formalized as a genus name, I believe by Olshevsky in his Mesozoic Meanderings, but correct me if I'm wrong.

So wy write "Brachiosaurus" brancai when, if considering this a separate genus, it should rightly be Giraffatitan brancai? I asked Mike about it, and apparently a paper explaining will be coming out in a week or so. The goss at SV-POW for quite some time has been that the SV-POWsketeers favor a separate genus for "B." brancai, but the assumption was always that this would be Giraffatitan. Mike is playing coy for now--is it simply that the authors don't like the name Giraffatitan? Mike says this is the only paper he's seen in which the acknowledgments contain an apology, so it sure sounds like that is close to the truth...

But a valid name can't be rejected simply because an author doesn't like the sound of it. It would have to be argued away on technical grounds. Is the fact that Giraffatitan was originally a subgenus, not a proper genus, coming into play and allowing Giraffatitan to be re-named? Is the apology directed towards George Olshevsky (maybe the authors don't consider his self-publications valid?). I don't know the ins and outs of priority when it comes to subgenera and subspecies. But we'll know shortly...