Gobiderma (Monstersauria) redescribed

[Ben Creisler <bscreisler@yahoo.com>]

From: Ben Creisler
bscreisler@yahoo.com
 
A recent Mesozoic reptile paper that apparently has not been mentioned yet on 
the DML. The pdf is free!
　
Conrad, Jack L., Rieppel, Olivier, Gauthier, Jacques & Norell, Mark (2011)
Osteology of Gobiderma pulchrum (Monstersauria, Lepidosauria, Reptilia).
Bulletin of the American Museum of Natural History 362: 88 pp.
URI: http://hdl.handle.net/2246/6149 
http://digitallibrary.amnh.org/dspace/handle/2246/6149
 
Abstract:
 
Joint expeditions by the American Museum of Natural History and Mongolian 
Academy of Sciences have recovered significant new remains of the basal 
monstersaur Gobiderma pulchrum. We describe these new specimens in detail and 
also revisit the originally described material in order to more fully 
understand this pivotal anguimorph taxon. The newly discovered specimens 
include skull and postcranial materials that add dramatically to the 
understanding of the osteology of Gobiderma pulchrum. We revise the diagnosis 
of this species, adding to the previously published diagnosis the following 
character states: premaxillary nasal process is narrowest mediolaterally; 
postfrontal and postorbital remain unfused; postorbital extends posteriorly for 
almost the entire length of the supratemporal fenestra; the Vidian canal is 
posteriorly enclosed by the parabasisphenoid; an anterior coracoid emargination 
is present; the pelvis is completely fused; and the lateral plantar
 tubercle is distally placed. A phylogenetic analysis confirms the placement of 
Gobiderma pulchrum as a non-helodermatid monstersaur. As such, the fact that it 
is known from reasonably complete remains makes it pivotal for understanding 
character evolution within Monstersauria. The Djadokhta Formation includes 
several carnivorous/insectivorous lizards and theropod dinosaurs--more than is 
usual for extant communities, but perhaps analogous in some ways to parts of 
modern Australia.