Postosuchus kirkpatricki (Chatterjee 1985, Weinbaum 2011) Late Triassic ~210 mya) 4-5 m long, was derived from a sister to Prestosuchus and was a sister to Saurosuchus within the Rauisuchidae. It was originally considered a close ancestor of the dinosaur T-rex.

Distinct from Saurosuchus, the skull of Postosuchus was shorter with a prefrontal crest anterior to the orbits and a reduction of the lateral temporal fenestra resulting from further invasion of the quadratojugal in contact with the postorbital. The anterior mandible was strongly upturned.

All the neural spines were longer, but those of the cervical series were especially tall.

The pectoral girdle was relatively smaller. The forelimbs were reduced. The carpal elements were coosified. A small manus attributed to a Postosuchus sister by Peyer et al. (2008) had four metacarpals of similar length, slightly longer laterally (except 5) and tiny fingers all of similar length. Such a manus is not typical for rauisuchids and the reduced fingers indicate only occasional usage, as a sometime prop on a chiefly bipedal reptile.

The ilium was substantially taller. The pubis had a large posteriorly directed "boot." The slender ischium had a smaller "boot." The entire pes was substantially longer, due in large part to the elongated metatarsals. Metatarsal I was more gracile. The Peyer et al. (2008) pes had a more robust digit 1 and shorter, more robust toes.

Sikannisuchus huskyi (Nicholls et al. 1998) is known from a large flat skull roof. The pattern of sutures most closely resembles that of Postosuchus, but derived in its own direction. Compare to the much smaller Postosuchus (Weinbaum 2011).

Chatterjee S 1985. Postosuchus, a new Thecodontian reptile from the Triassic of Texas and the origin of Tyrannosaurs. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences 309 (1139): 395–460. doi:10.1098/rstb.1985.0092.

Nicholls EL, Brinkman DB and Wu K-C 1998 A new archosaur from the Upper Triassic
Pardonet Formation of British Columbia. Canadian Journal of Earth Science 35: 1134–1142.

Novak SE 2004. A new specimen of Postosuchus from the Late Triassic Coelophysis Quarry, siltstone member, Chinle Formation, Ghost Ranch, New Mexico. M.S. thesis, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.

Peyer K Carter, JG, Sues H-D, Novak SE, and Olsen PE 2008. A new Suchian Archosaur from the Upper Triassic of North Carolina. Journal of Vertebrate Paleontology 28 (2): 363–381. doi:10.1671/0272-4634(2008)28[363:ANSAFT]2.0.CO;2.

Weinbaum JC 2011. The skull of Postosuchus kirkpatricki (Archosauria: Paracrocodyliformes) from the Upper Triassic of the United States. PaleoBios 30(1) 18-44.

wiki/Postosuchus