Thursday, February 4, 2010
Banji the Hunted
Recently, some of my adventures on Wikipedia have addressed the question of oviraptorid beaks. Now, contain yourselves, I know this sounds a little too exciting. But it's really a very rarely addressed topic. It's obvious that oviraptorids had beaks of some kind, with their strong, toothless, pointy jaws that don't quite close right when unsheathed by rhamphotheca (the keratinous covering that forms the beak). But just how these beaks looked and to what extent they covered the jaws hasn't been studied in a lot of detail.
I asked about this a few times back on the old version of dinoforum, and some commentors there (especially oviraptorer Jaime Headden) were very helpful in pulling educated guesses based on modern analogues. Jaime's conclusion, IIRC, was that most oviraptorids have been constructed with beaks that are too large or, more specifically, cover too much of the skull and jaws. You can see the difference in two versions of my own ovi profile drawings, old one here with extensive beaks, new one with corrected beak after Headden here. Note also the more subtle difference--the beaks on the newer version meet flush, without the upper beak overlapping the other (what use would that be?) and the beak does not incorporate the nostril, which is the exception, not the rule in modern beaked animals like birds and turtles.
The first real scientific work on this topic has not yet hit the official literature, but an unpublished phD thesis by Stig Jansen addresses this topic and can be read here. Jansen also has a similar unpublished paper floating around for ornithomimid beaks, I'm sure you're Google-fu will turn it up.
Jansen's thesis comes to essentially the same conclusions as Headden did, and presents two potential extremes for the extent of oviraptorid beaks, illustrated by him above. Interestingly, one of the options has a keratin-less crest. Traditionally, crested oviraptorids or those with tall, pronounced skulls have been restored with horny, cassowary-like casques, though there was never any direct evidence for this, and they could just as well have been covered in skin or feathers.
Banji long, or "dragon with striped crest"... this is, incidentally, another case of bad grammar in a binomial. The specific name is supposed to be an adjective, not a noun, which makes for very awkward translations like Mei long, or "dragon, comma, soundly sleeping". Also, it sounds like Benji.). Anyway, Banji reserves some unique vertical striations on its crest. The implications of this feature aren't discussed in the paper, but the first thing that jumps to my mind is that these may form the bases of more pronounced striations in an overlying keratinous crest. As Jansen shows, underlying bony features of a bak often subtly reflect larger features of the keratin, like the keratinous pseudo-teeth on the beaks of some oviraptorids. A future paper will describe Banji and its implications in more detail, so we'll see if this ends up supported by actual study of the fossils, but right now it's a very interesting possibility that may argue for the more extensive beak suggested by Jansen's thesis.