Postosuchus kirkpatricki
- 演化之聲
- Mar 18
- 2 min read
Age
Triassic（Norian-Rhaetian）
221-203 Ma
Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Family: Rauisuchidae
Genus: Postosuchus
Species: Postosuchus kirkpatricki
Morphological description
The skull of Postosuchus kirkpatricki is elongate and relatively narrow, with an average length of approximately 55 cm. The most distinctive autapomorphic features include a prominent rugose ridge along the lateral surface of the maxilla, and a large triangular fossa on the anteromedial surface of the ascending process of the maxilla that contains a foramen. The dentition is heterodont and fang-like, with a clear size differentiation between the anterior and posterior maxillary teeth.
The dermatocranium bears fossae and foramina resembling those seen in crocodylomorphs, features that are rare among other basal pseudosuchians. The infratemporal fenestra is subdivided into upper and lower openings by the forward projection of the squamosal and quadratojugal. The mandible is robust, comparable to that of other rauisuchians such as Batrachotomus and Saurosuchus.
The jugal is triradiate, continuing the rugose ridge from the maxilla across its lateral surface before tapering posteriorly. The squamosal is thick and overlaps the postorbital anteriorly, connects posteriorly with the parietal, and forms a ventral concavity that accommodates the dorsal portion of the quadrate. At the junction between the quadratojugal and quadrate, a distinct quadrate foramen is present, representing another characteristic feature of this group.
Etymology
posto-: refers to the locality where the holotype was discovered, the Post Quarry in Texas, USA.
-suchus: derived from Greek, meaning crocodile.
kirkpatrick: named in honor of Mr. Kirkpatrick, the landowner who permitted fossil excavation and collection on his property.
Biological description
Postosuchus kirkpatricki is an extinct paracrocodylomorph pseudosuchian archosaur that lived during the Late Triassic in what is now the southwestern and eastern United States. As one of the apex predators of its ecosystem, it was likely among the largest terrestrial carnivores in its environment, reaching lengths of up to 9 meters.
The holotype (TTUP 9000) and paratype (TTUP 9002) specimens were recovered from the Post Quarry of the Cooper Canyon Formation in Garza County, Texas. These specimens include a skull, most limb bones, vertebrae, and portions of the pelvis.
The species was first named and described by Sankar Chatterjee in 1985 based on remains from twelve individuals, including two large specimens estimated at 4 to 6 meters in length and ten smaller individuals measuring approximately 2 to 3 meters. These smaller specimens were initially interpreted as juveniles of the same species. However, later studies suggested that these smaller individuals belong to a distinct taxon, Chatterjeea elegans.
Additionally, some skeletal elements originally attributed to Postosuchus were later reassigned by subsequent researchers, as Chatterjee had mistakenly included material from other species in the original description.
（Author: Shui-Ye You）
References
Weinbaum JC. (2011). The skull of Postsuchus kirkpatricki (Archosauria: Paracrocodyliformes) from the Upper Triassic of the United States. PaleoBios.
Chatterjee S. (1985). Postosuchus, a New Thecodontian Reptile from the Triassic of Texas and the Origin of Tyrannosaurs. JSTOR.
29.38, -100.39
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