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Abyssomedon, new nyctiphruretid parareptile from Early Permian of Oklahoma

Ben Creisler

A new paper:

Mark J. MacDougall and Robert R. Reisz (2014)
The first record of a nyctiphruretid parareptile from the Early
Permian of North America, with a discussion of parareptilian temporal
Zoological Journal of the Linnean Society 172(3): 616–630
DOI: 10.1111/zoj.12180

The Richards Spur Locality of Oklahoma, USA, long known for its highly
diverse Early Permian terrestrial tetrapod assemblage, is particularly
interesting for the presence of many endemic taxa. The parareptilian
component of the assemblage, rare members of other Early Permian
communities, is especially diverse at Richards Spur, consisting of six
species. The newest parareptile, Abyssomedon williamsi gen. et sp.
nov., consists of an articulated left jaw and various disarticulated
cranial and postcranial elements. A new phylogenetic analysis of
parareptiles, based on an updated modified data matrix revealed that
Ab. williamsi is a member of the small clade Nyctiphruretidae. This
makes Ab. williamsi the first and oldest nyctiphruretid, a clade of
parareptiles otherwise known from the Middle and Late Permian of
Russia, extending the age of the clade back into the Early Permian.
This discovery also raises the possibility that nyctiphruretids may
have dispersed from western Laurasia to eastern Laurasia. The
characteristic jugal morphology of Ab. williamsi shows that it would
have possessed a slender, deep, temporal emargination. The current
topology of Parareptilia indicates that there was considerable
variability in the patterns of lateral temporal openings amongst the
various members of this clade, suggesting that there may have been
multiple, independent modifications of this region of the skull.