Taxonomy of the proterosuchid archosauriforms (Diapsida: Archosauromorpha) from the earliest Triassic of South Africa, and implications for the early archosauriform radiation

Proterosuchidae is one of the first clades of Archosauriformes (archosaurs and closely related species) to appear in the fossil record, with the richest sample of the group coming from the Lystrosaurus Assemblage Zone (earliest Triassic) of South Africa. Four nominal proterosuchid species were described from South Africa during the twentieth century (Proterosuchus fergusi, Chasmatosaurus vanhoepeni, Chasmatosaurus alexanderi and Elaphrosuchus rubidgei), but interpretations of their taxonomy have been widely disparate. The most recent taxonomic revision concluded that P. fergusi is the only valid species and that the other nominal species are junior subjective synonyms of this taxon. This proposal was based on the interpretation that anatomical differences between the nominal species could be explained as a result of ontogenetic changes and/or post-mortem deformation. The recent discoveries of multiple new South African proterosuchid specimens provide an impetus to revisit their taxonomy...

前龙科（Proterosuchidae）是化石记录中出现的首批主龙形类（Archosauriformes，主龙类及其近缘物种）演化支之一，该类群的标本以南非水龙兽组合带（Lystrosaurus Assemblage Zone，早三叠世最早期）所产最为丰富。20世纪期间，学界已从南非记述了4个命名前龙科物种：费氏前龙（Proterosuchus fergusi）、范氏驰顶鳄（Chasmatosaurus vanhoepeni）、亚历山大驰顶鳄（Chasmatosaurus alexanderi）以及鲁氏埃拉弗鳄（Elaphrosuchus rubidgei），但针对其分类学的解读长期存在显著分歧。最新的分类学修订研究认定，仅费氏前龙为有效物种，其余命名物种均为该物种的主观次同物异名。该结论的依据为：各命名物种间的解剖学差异，可归因于个体发育变化与/或死后变形。近期南非境内多件新发现的前龙科标本，为重新审视该类群的分类学问题提供了重要契机。