Postosuchus alisonae Peyer et al., 2008

Nesbitt, Sterling J., 2011, The Early Evolution Of Archosaurs: Relationships And The Origin Of Major Clades, Bulletin of the American Museum of Natural History 2011 (352), pp. 1-292 : 37-38

Postosuchus alisonae Peyer et al., 2008

AGE: Late Carnian–early Norian ( Olsen and Huber, 1997).

OCCURRENCE: Mudstone of Lithofacies Association II sensu Hoffman and Gallagher (1989), south-central region of Durham subbasin of Deep River Basin, Newark Supergroup, West Genlee, Durham County, North Carolina, U.S.A. Equivalent to the lower Sanford Formation ( Huber et al., 1993).

HOLOTYPE: UNC 15575, partial skeleton consisting of a few fragmentary cranial bones (nasal, frontal, squamosal, prootic, supraoccipital, left and right opisthotic, articular, angular, prearticular) and isolated teeth. The postcranial skeleton includes seven cervical, one dorsal, and four caudal vertebrae, with associated ribs and chevrons, partial sacral rib, cervical, dorsal, and caudal osteoderms, gastralia, right and partial left coracoid, partial left and right scapulae, interclavicle, clavicle, left and right humeri, radii, and ulnae, nearly complete right and partial left manus, distal ends of left and right pubes, left and right tibiae, fibulae, tarsi, and pedes ( Peyer et al., 2008).

REMARKS: Peyer et al. (2008) described a well-preserved partial skeleton of a suchian from the Late Triassic of the Newark Supergroup. The preserved portions of the skeleton are nearly identical to those of Postosuchus kirkpatricki except for the one clear autapomorphy stated above. Unfortunately, few comparisons can be made to Polonosuchus (ZPAL Ab III/543) because there are few elements that are shared by the known specimens of the two taxa, and those parts that do overlap either support a close relationship between Postosuchus kirkpatricki , Postosuchus alisonae , and Polonosuchus or represent plesiomorphies within Archosauria or more inclusive clades. Postosuchus alisonae remains one of only a few Triassic crocodylian-line archosaurs with articulated manus and pedes in the same individual.

Postosuchus alisonae is almost identical to Postosuchus kirkpatricki (see Peyer et al., 2008) in the overlapping elements. Postosuchus alisonae differs from all known suchians in the presence of a groove in the proximal portion of metacarpal I for contact with metacarpal II ( Peyer et al., 2008).

KEY REFERENCES: Peyer et al., 2008.