Smilosuchus gregorii ( Camp, 1930 )

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 : 18-19

Smilosuchus gregorii ( Camp, 1930) , sensu Long and Murry, 1995 ( fig. 7J) (5 Machaeroprosopus gregorii Camp, 1930 )

AGE: Early-mid Norian, Late Triassic ( Irmis and Mundil, 2008).

OCCURRENCE: Blue Mesa Member of the Chinle Formation, Arizona.

HOLOTYPE: UCMP 27200, complete skull with mandible, eight vertebrae, a femur and osteoderms.

REFERRED MATERIAL: USNM 18313, partial skull, complete mandible, and nearly complete postcranial skeleton; AMNH FR 3060, skull, mandible, pelvis, osteoderms, partial hind limb.

REMARKS: Smilosuchus represents one of the largest phytosaurs (skull length.1.5 m) recovered from the Chinle Formation. As with most phytosaur specimens, the holotype of Smilosuchus consists of a skull and only fragments of the postcrania. Therefore, I rely on the nearly complete, disarticulated postcranial skeleton with associated skull of USNM 18313 for scoring postcrania. The ankle of USNM 18313 has figured prominently in studies of phytosaur locomotion ( Parrish, 1986) and the origin of the ‘‘crocodile-normal’’ ankle type ( Sereno, 1991a).

KEY REFERENCES: Camp, 1930; Gregory, 1962; Colbert, 1947; Ballew, 1989; Long and Murry, 1995; Stocker, 2008.