group of reptiles

The Crurotarsi are one of the two main groups of archosaurs. It includes the archosaurs (living today are crocodiles and birds). It also includes all their ancestors and relatives right back to the early Triassic period, including the Pseudosuchia.[1]

Temporal range:
Lower TriassicPresent, 250–0 mya
Protome batalaria.jpg
Life restoration of Protome batalaria
Ornithosuchus BW.jpg
Life restoration of Ornithosuchus woodwardi
Scientific classification e
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauriformes
Clade: Crurotarsi
Sereno & Arcucci, 1990


Both main groups of Archosaurs are defined by features of their ankle joints.[2][3]


  1. Sereno, Paul 1991. Basal archosaurs: phylogenetic relationships and functional implications. Journal of Vertebrate Paleontology 11 (Suppl. 4): 1–51.
  2. Sereno P.C. & Arcucci A.B. 1990. The monophyly of crurotarsal archosaurs and the origin of bird and crocodile ankle joints. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 180: 21–52.
  3. Nesbitt S.J. 2011. The early evolution of archosaurs: relationships and the origin of major clades. Bulletin of the American Museum of Natural History 352: 1–292. [1]