Proterochampsidae

The Proterochampsidae, or proterochampsids, are a group of mysterious archosauromorphs named in 1966 by A.S. Romer in his book Vertebrate Paleontology, 3rd edition. Various authorities place them as archosaurs (Benton 1985, Benton 1990), Proterosuchia (Carroll 1988), the Archosauriformes (Sereno 1991), and more recently by certain online databases as either a non-extant taxon or a Crocodylomorph. The family (and rarely order) are based on around fifty specimens from Argentina and surrounding areas of Patagonia. Known specimens are estimated to be between 245 and 199.6 Ma- placing them in the Triassic period.

Defining Characteristics
In Romer's book the Proterochampsidae are defined as having Broad, low skull with small dorsal fenestra; no parietal (pineal) foramen or fossa [P93]; postorbital with strong, dorsally rugose, horizontal crest [S91]; foramina for internal carotids lateral to basipterygoid process [P93]; vertebral intercentra absent [S91] [P93]; primitive plate-like pelvis; calcaneal tuber with some posterior deviation from lateral projection [P93]; astragalar facets for tibia & fibula adjacent [S91]; calcaneal tuber taller than broad [P93]; calcaneal facet for fibula continuous with facet for distal tarsal IV [P93]; calcaneum with hemicylindrical facet for astragalus [P93]; dermal armor present [P93]; aquatic predators from West Gondwanaland. Parrish (1993) [P93] and Sereno (1991) [S91] back up these claims.

Ecology
This family includes animals cut very different between them, but all species have bodily characteristics similar to those of crocodiles. Some proterocampsids failed to meet the length of one meter, but others like Proterochampsa reached five meters in length, and were undoubtedly among the largest predators of the Triassic. The first fossil remains of proterocampsids were included in the group of phytosaurs, but further research showed that these animals are both too primitive and too specialized to be classified in this group. Scientists now consider this ancestral family as a group of genuine archosaurs, similar to the families of proterosuchids and erythrosuchids.

Taxonomy
Proterochampsidae was named by Romer (1966). It is not extant and is not an ichnofossil or a form taxon. It was assigned to Proterosuchia by Carroll (1988); to Archosauria by Benton (1985) and Benton (1990); and to Archosauriformes by Sereno (1991). A basic yet usually not accepted taxonomy is below:


 * Order Proterosuchia - not accepted
 * Family Proterochampsidae
 * Genus Cerritosaurus (Price, 1946) -assigned to the Proterochampsidae by Carroll (1988)
 * Genus Chanaresuchus (Romer, 1971) -assigned to the Proterochampsidae by Romer (1971), Carroll (1988), and Benton (1990)
 * Species C. bonapartei (Romer, 1971)
 * Genus Gualosuchus (Romer, 1971) -assigned to the Proterochampsidae by Romer (1971) and Carroll (1988)
 * Species G. reigi (Romer, 1971)
 * Genus Proterochampsa (Reig, 1959) -assigned to the Proterochampsidae by Carroll (1988)

Links

 * | Proterochampsidae on Palaeos
 * Taxon on Mikko's Phylogeny Archive
 * On the Checklist on Non-Avian DInosaurs
 * | On Biolib
 * | On the Paleobiology Database
 * | Page on Italian Wikipedia
 * | Page on Basal Archosaurs