Revising the Oviraptor Myth

What follows is an historical essay on a subject which was intended for eventual presentation at SVP (here, the second abstract), as part of a projection on research that would resolve something that has never been practically tested. This essay is updated from scraps of data strewn about and leads nicely into current work that should help to resolve some of the issues I raise here. It is not intended to have a conclusion, but to be a part of a larger research paper that would include the practical experiment followed by whatever conclusion I would make of said experiment.

Way back when, the American Museum of Natural History funded a series of expeditions into Central Asia (the CAEs, or Central Asian Expeditions, of which there ) at the behest of then-museum president Henry Fairfield Osborn, under the auspice that they were to discover the ancient origins of Man deep in Asia. While Osborn’s reasons for this (opposing the “out-of-Africa” hypothesis) are irrelevant here, his resources were not, and he would send several expeditions into northern China and southern Mongolia (territory claimed at the time by China). What they discovered there spanned the Paleogene and Late Cretaceous epochs, and supplied the AMNH with ample material from which to spend the next several decades analyzing.

On one of the last expeditions, at Bayn Zag (a site under the cliffs of of the same name, called Shabarakh Usu or “Flaming Cliffs,” and a part of the Djadokhta Formation, which would only become more famous in time) George Olsen [n1] found this:

Oviraptor philoceratops, AMNH 6517 (holotype and only known skeletal specimen).

Splitting Chirostenotes

Seems audacious of me, eh? Chirostenotes (specifically, Chirostenotes pergracilis) enjoys one of the more interesting synonymy lists among dinosaurs, as it contains (or has contained) no fewer than three generic synonyms and four specific synonyms, but also that it has almost never contained all of these at once, with various authors adding or removing various names depending on newer finds. This has been aided by the difficulty of finding complete or reasonably replete skeletal material of singular individuals of small dinosaurs in the Dinosaur Park Formation of southern Alberta. Instead, partial material abounds. This partial material has led to a rich lesson in synonymy. So … here goes.

Caenagnathidae, comparison of various known skeletal material. Note the exclusion of Caenagnathus collinsi; this is intentional, although I should include it anyways. The three skeletons on the right are considered Chirostenotes (the top is Chirostenotes sp., a non-determinate designation, while the others seem comfortably Chirostenotes pergracilis), the two on the left Elmisaurus rarus.

When Does Morphology Trump Ontogeny?

An outstanding issue among some systematists is the question when, in a given sample, a series of recognized taxa are argued to be an array of successively distant sister taxa versus a reflection of transformation in an ontogenetic series in a more confined concept of a species. Leaving out the question of what a species or how fine the variation should be calibrated, how do we tell when morphological variation is sufficient enough to contradict implied ontogeny? Which of these, would also be the null hypothesis?

A recent paper by Andy Farke, a ceratopsian specialist at the Raymond M. Alf Museum of Paleontology in Claremont, California, USA, seeks to resolve a question I discussed earlier here. In it, he tackles the issue of whether a particular specimen, USNM 2412 (the holotype of Nedoceratops hatcheri; formerly Diceratops hatcheri, then named Diceratus hatcheri followed by Nedoceratops hatcheri when it was found that Diceratops was preoccupied … by an insect {this happens a lot}) is morphologically distinct enough not to be conflated into a variation-rich species complex confined to Triceratops. Again, we’re leaving the question of “what is a species?” out this time around.

Skull of Nedoceratops hatcheri, USNM 2412 (holotype). A-B, right lateral; C-D, left lateral views; A,C, photos of the skull; B,D, line drawings of the same skull, with grey indicating missing (restored) material and yellow remaining unprepared matrix. From Farke (2011:fig.1).

Better Know a [Dinosaur] – Elmisaurus rarus

This post won’t have much to do with teeth. This will eventually occur, when I focus on toothy things like Suminia (favorite non-mammalian synapsid) or toothless (and known-jawed but edentulous) in which case we come to the oviraptorosaurs, which are odder than you think.

And, plus, I had this image lying around…

Skeletons in silhouette of Elmisaurus rarus. On the left (black silhouette) includes the holotype specimen (ZPAL MgD-I/172, pes) and referred manus+pes material (ZPAL MgD-I/98, partial manus and pes); on the right is the same material expanded to the size of a referred manus+pes (ZPAL MgD-I/20), showing the largest known specimen. Both of these represent only Elmisaurus rarus.