Big Beak – Wp#11


Some taxa deserve a little more attention than others. We are all familiar with name-sake dinosaurs, with names like Tyrannosaurus rex, Triceratops horridus, or even Oviraptor philoceratops (although I am sure what you think you know about Oviraptor philoceratops is not necessarily true!). In some occasions, a few dinosaurs that are fairly well known in science are not so much at all. In oviraptorids alone, museum specimens are routinely figured with names like Conchoraptor gracilis or “Ingenia” yanshini [n1]. Very few of these specimens make use of the osteological qualities that separate those two taxa, which are largely postcranial, and do so interchangeably based on the idea that all crestless oviraptorids are either Conchoraptor or “Ingenia“. One such specimen is almost certainly neither.

Skull of an unnamed Conchoraptor-like oviraptorid. The skull and mandible in various views. From left to right, top to bottom: Skull in anterior, left lateral, posterior, and dorsal view; mandible in dorsal view; skull in ventral view, mandible in ventral view; braincase with lateral bones (postorbital, squamosal, quadrate, and the arms of the paroccipital processes) removed; mandible in left lateral and right medial views. Each square of the grid represents 1 centimeter.

Skull of an unnamed Conchoraptor-like oviraptorid. The skull and mandible in various views. From left to right, top to bottom: Skull in anterior, left lateral, posterior, and dorsal view; mandible in dorsal view; skull in ventral view, mandible in ventral view; braincase with lateral bones (postorbital, squamosal, quadrate, and the arms of the paroccipital processes) removed; mandible in left lateral and right medial views. Each square of the grid represents 1 centimeter.

For want of a name, I will refer to this specimen as “Big Beak.” It is currently accessioned in the Paleontological Institute [Палеонтологический институт] (PIN) of the Russian Academy of Sciences [Российская академия наук] in Moscow, Russia. I do not know the actual specimen number, but casts have been made available to various parties, and this illustration is based on some of those casts and photos of the original.

Based only on my own analysis, one can discriminate Conchoraptor gracilis and “Ingenia” yanshini, although as noted above this is based primarily on postcranial material (chiefly, in features of the manus, such as the relative length of the first digit to the others, its diameter, and the relative sizes of the other digits and their unguals). Based on a jaw considered part of the “Ingenia” yanshini holotype [1], there is also a distinct difference between these taxa in that the dentary is far more curved in “Ingenia” yanshini than it is in Conchoraptor gracilis. But more than this, various other features of the skull (including the holotype “Ingenia” yanshini braincase [1,2] and the holotype skull of Conchoraptor gracilis [3]) including a highly sloped occiput and forwardly “skewed” cranium, resembling the condition seen in Citipati osmolskae [4]. The skull is also very distinct in the huge orbit, vertical premaxilla, bowed anterior edge of the premaxilla, and the shape of the maxilla itself, among other features. The skull is not particularly small (over 10cm, putting it in the size range of GI 100/20, holotype of Conchoraptor gracilis), despite the apparent juvenile aspect of the very large orbits, and while this does not mean the taxon is not a juvenile, the bones of the skull are well-ossified, with fusion between the parietals, and it may indicate merely that the skull was exceptionally ossified at a young age.

Nonetheless, the skull represents an animal that seems distinct from other oviraptorosaurs, and is probably a new taxon.

[1] Barsbold R. 1981. Беззубйе хыщние динзавру Монголий [(Bezzubiye khishchniye dinozavry Mongolii) Edentulous carnivorous dinosaurs of Mongolia]. Trudy — Sovmestnaya Sovyetsko-Mongol’skaya Palyeontologicheskaya Ekspeditsiya 15:28-39,124.
[2] Barsbold R. 1983. Хыщние динзавру мела Монголий [(Khishchniye dinozavry myela Mongolii) Carnivorous dinosaurs from the Cretaceous of Mongolia]. Trudy — Sovmestnaya Sovyetsko-Mongol’skaya Palyeontologicheskaya Ekspeditsiya 19:1-120.
[3] Barsbold R. 1986. Raubdinosaurier Oviraptoren [The robbing dinosaurs — oviraptors]. pg. 210-223 in Vorob’yeva (ed.) Herpetologische Untersuchungen in der Mongolischen Volksrepublik [Herpetological investigations from the People’s Republic of Mongolia]. (Akademia Nauk, SSSR, Moscow.)
[4] Clark, J. M., Norell, M. A., & Barsbold R. 2001. Two new oviraptorids (Theropoda: Oviraptorosauria), Upper Cretaceous Djadokhta Formation, Ukhaa Tolgod, Mongolia. Journal of Vertebrate Paleontology 21(2):209-213.

[n1] The name Ingenia was used for a nemotode (Ingenia mirabilis Gerlach, 1957), derived from the Latin ingenium (character, quality, or attribute) rather than from the Mongolian place name Ingen Khoboor. Because of this, the dinosaurian name must be replaced, and is used in quotes.

Edit:Ingeniayanshini has now been renamed Ajancingenia yanshini, via Easter (2013), and as such the issue of preoccupation is no more.

Advertisements
This entry was posted in Paleontology and tagged , . Bookmark the permalink.

5 Responses to Big Beak – Wp#11

  1. Gera says:

    Hi Jaime! There is an error – Paleontological Institute (PIN) of the Russian Academy of Sciences is in Moscow, not in St. Petersburg ;)

  2. Pingback: An Oviraptorosaur Alphabet | The Bite Stuff

  3. Pingback: Conchoraptor Gracilis | PALEOREPLICA

  4. Pingback: A Fanboyish Squee Goes Out To… | The Bite Stuff

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s