Affiliation:
1. Department of Biology, University of Toronto at Mississauga, 3359 Mississauga Road, Mississauga, Ontario, Canada L5L 1C6
2. International Centre of Future Science, Jilin University, 2699 Qianjin Avenue, Changchun, Jilin Province, People's Republic of China
Abstract
Varanopids are a basal clade of small- to medium-sized non-therapsid synapsids, whose range extends from the late Pennsylvanian to the late middle Permian, and are found in North America, Russia, Europe and South Africa. The greatest varanopid diversity is observed at the fossiliferous cave deposits near Richards Spur, Oklahoma, well known for the preservation of a complex early Permian upland community. Two previously described varanopids,
Mycterosaurus
and
Varanops
, are known only from fragmentary disarticulated material at Richards Spur. A third putative varanopid,
Basicranodon fortsillensis
, represented by a partial parasphenoid, has been synonymized with
Mycterosaurus longiceps
. This study reports on a new varanopid taxon, represented by substantially more complete material, including three nearly complete skulls. Such comprehensive cranial material allows for a detailed study of the taxon and its relationship to other varanopids. This new varanopid bears great morphological similarity to
Mesenosaurus romeri
from the middle Permian Mezen River Basin of northern Russia. Phylogenetic analysis recovers a sister relationship between this taxon and
Me. romeri
. This relationship, in conjunction with a detailed morphological comparison, supports the placement of this taxon within
Mesenosaurus
, as a new species,
Me. efremovi
. These results reveal an unexpected extension of the geographical and temporal range of
Mesenosaurus
, contributing to our understanding of varanopid dispersal. The extended persistence of this basal clade of predatory synapsids, underscored by the apparent evolutionary stasis of this genus, is unusual among Palaeozoic tetrapods. This phenomenon implies an exceptionally high degree of extended ecological resilience across major faunal and environmental transitions.
Funder
Ontario Council on Graduate Studies, Council of Ontario Universities
University of Toronto
Natural Sciences and Engineering Research Council of Canada
Cited by
9 articles.
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