Cranial anatomy and taxonomy of the erythrosuchid archosauriform ‘Vjushkovia triplicostata’ Huene, 1960, from the Early Triassic of European Russia

BUTLER, RICHARD J.; SENNIKOV, ANDREY G.; DUNNE, EMMA M.; EZCURRA, MARTIN D.; HEDRICK, BRANDON P.; MAIDMENT, SUSANNAH C. R.; MEADE, LUKE E.; RAVEN, THOMAS J.; GOWER, DAVID J.

Royal Society Open Science

Royal Society

Año: 2019 vol. 6

2054-5703

Erythrosuchidae are a globally distributed and importantgroup of apex predators that occupied Early and MiddleTriassic terrestrial ecosystems following the Permo-Triassicmass extinction. The stratigraphically oldest known genus ofErythrosuchidae is Garjainia Ochev, 1958, which is knownfrom the late Early Triassic (late Olenekian) of EuropeanRussia and South Africa. Two species of Garjainia have beenreported from Russia: the type species, Garjainia primaOchev, 1958, and ?Vjushkovia triplicostata? von Huene, 1960,which has been referred to Garjainia as either congeneric (Garjainia triplicostata) or conspecific (G. prima). The holotype of G. prima has received relativelyextensive study, but little work has been conducted on type or referred material attributed to?V. triplicostata?. However, this material includes well-preserved fossils representing all parts of theskeleton and comprises seven individuals. Here, we provide a comprehensive description andreview of the cranial anatomy of material attributed to ?V. triplicostata?, and draw comparisonswith G. prima. We conclude that the two Russian taxa are indeed conspecific, and that minordifferences between them result from a combination of preservation or intraspecific variation.Our reassessment therefore provides additional information on the cranial anatomy of G. prima.Moreover, we quantify relative head size in erythrosuchids and other early archosauromorphs inan explicit phylogenetic context for the first time. Our results show that erythrosuchids do indeedappear to have disproportionately large skulls, but that this is also true for other earlyarchosauriforms (i.e. proterosuchids), and may reflect the invasion of hypercarnivorous niches bythese groups following the Permo-Triassic extinction.