Vigilosaurus

Vigilosaurus is an extinct genus of reptiles from the Permian-aged Guodikeng Formation of Xinjiang, China. The genus contains a single species, Vigilosaurus gaochangensis, known from a partial left hindlimb.^[1]

Vigilosaurus Temporal range: Late Permian (Changhsingian), 252.2 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Diapsida
Clade:	Neodiapsida
Genus:	†Vigilosaurus Chen & Liu, 2023
Species:	†V. gaochangensis
Binomial name
†Vigilosaurus gaochangensis Chen & Liu, 2023

Classification

When it was described in 2023, the Vigilosaurus holotype was identified as a possible member of the archosauriform clade Proterochampsia. This would make Vigilosaurus one of the oldest known archosauromorphs, indicating they had diversified much more rapidly than previously thought.^[1] However, a 2025 publication revisited the specimen, recovering it outside of the Archosauromorpha altogether. Instead, it was identified as outside of the reptile crown group (Sauria), diverging after the South African genus Youngina.^[2] These contrasting results are displayed in the cladograms below:

Topology 1: Results of Chen & Liu (2023)[1] Archosauriformes Proterosuchidae Antarctanax Sarmatosuchus Cuyosuchus Erythrosuchidae Dorosuchus Asperoris Euparkeria Halazhaisuchus Avemetatarsalia Proterochampsia Polymorphodon Vigilosaurus Litorosuchus Vancleavea Other proterochampsians

Topology 2: Results of Ezcurra, Sues & Fröbisch (2025)[2] Orovenator Claudiosaurus Acerosodontosaurus Hovasaurus Youngina Vigilosaurus Choristodera Sauria Lepidosauromorpha Manistropheus Aenigmastropheus Protorosaurus Jesairosaurus + Tanysauria Crocopoda ⇒ Archosauriformes