Archosauriformes

Archosauriformes Temporal range: Lopingian - Recent, 260–0 Ma PreЄ Є O S D C P T J K Pg N
life restoration of Euparkeria capensis
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
clade:	Sauria
Infraclass:	Archosauromorpha
Node:	Archosauriformes Gauthier, 1986
Subgroups
Archosauria †Erythrosuchidae †Euparkeriidae †Proterochampsidae †Proterosuchidae †Turfanosuchus †Yonghesuchus †Uatchitodon

Archosauriformes (Greek for 'ruling lizards', and Latin for 'form') is a clade of diapsid reptiles that developed from archosauromorph ancestors some time in the Late Permian (roughly 250 million years ago). These reptiles, which include members of the family Proterosuchidae and more advanced forms, were originally superficially crocodile-like predatory semi-aquatic animals about 1.5 meters long, with a sprawling elbows-out stance and long snouts. Unlike the bulk of their therapsid contemporaries, the proterosuchids survived the catastrophe at the end of the Permian, perhaps because they were opportunistic scavengers, perhaps because they could retreat into water to find respite from an overheated climate. Any such scenarios are hypothetical; what is clearer is that these animals were highly successful in their new environment, and evolved quickly. Within a few million years at the opening of the Triassic, the proterosuchids had given rise to the Erythrosuchidae (the first sauropsids to totally dominate their environment), who in turn were the ancestors of the small agile Euparkeriidae, from whom a number of successfully more advanced families - the archosaurs proper - evolved rapidly to fill empty ecological niches in the devastated global system.

Pre-Euparkeria Archosauriformes were in the past included in the suborder Proterosuchia of the order Thecodontia. Under the cladistic methodology, Proterosuchia is rejected as a paraphyletic assemblage, and the pre-archosaurian taxa are simply considered as basal Archosauriformes.

Taxonomy

• Class Reptilia
  • Infraclass Archosauromorpha
    • (unranked) ARCHOSAURIFORMES
      • Uatchitodon
      • Family Proterosuchidae
      • Family Erythrosuchidae
      • Family Euparkeriidae
      • (unranked)
        • Turfanosuchus
        • Yonghesuchus
        • Family Proterochampsidae
        • (unranked) Archosauria [Crown group Archosauria = Avesuchia]

Below is a cladogram from Ezcurra et al. (2010):

Archosauriformes	Proterosuchus Sarmatosuchus Fugusuchus Osmolskina Koilamasuchus  Erythrosuchidae  Shansisuchus Vjushkovia Erythrosuchus Euparkeria Chanaresuchus Vancleavea Doswellia  Archosauria  Pseudosuchia Avemetatarsalia

Below is a cladogram from Nesbitt (2011):

Archosauriformes	Proterosuchus Erythrosuchus Vancleavea  Proterochampsia  Tropidosuchus Chanaresuchus Euparkeria  Phytosauria*  Parasuchus Smilosuchus Pseudopalatus  Archosauria  Pseudosuchia Avemetatarsalia *Note: Phytosaurs are usually placed within Pseudosuchia, or crocodile-line archosaurs

Literature

• Gauthier, J. A. (1986), "Saurischian monophyly and the origin of birds", in Padian, K., The Origin of Birds and the Evolution of Flight. Memoirs of the California Academy of Sciences, 8, California Academy of Sciences, pp. 1–55, ISBN 780940228146 
• Gauthier, J. A.; Kluge, A. G.; Rowe, T. (June 1988). "Amniote phylogeny and the importance of fossils". Cladistics (John Wiley & Sons) 4 (2): 105–209. doi:10.1111/j.1096-0031.1988.tb00514.x. 

External links

• Paleos
• Mikko's Phylogeny Archive