Parringtonia is an extinct genus of Triassic archosaur within the family Erpetosuchidae, known from the type species Parringtonia gracilis. It is known from a single specimen, NHMUK R8646, found from the Anisian-age Manda Formation of Tanzania. This specimen, like most archosaur material from the Manda Formation, is fragmentary, including only a maxilla and a few postcranial bones. They show similarities with those of another archosaur called Erpetosuchus, known from the Middle Triassic of Scotland and the eastern United States. The phylogenetic placement of Parringtonia and Erpetosuchus are uncertain; some studies placed them close to the group Crocodylomorpha, which includes all modern crocodylians and many extinct forms that diversified after the Triassic, but this relationship has more recently been questioned.
NHMUK R8646 consists of a right maxilla or upper jaw bone, a left scapula or shoulder blade, part of what might be the ischium bone of the pelvis, five complete and four partial dorsal vertebrae, three caudal vertebrae, and five osteoderms. Some vertebrae show suture lines where different parts have begun to fuse, indicating that the individual was immature when it died. NHMUK R8646 most closely resembles the bones of Erpetosuchus granti from Scotland and Erpetosuchus sp. from the eastern United States. The teeth are restricted to the front half of the maxillae in Parringtonia and Erpetosuchus, and the back of the maxilla is thicker than it is tall. Parringtonia has five tooth sockets, Erpetosuchus granti only four, and Erpetosuchus sp. six or more. Unlike Erpetosuchus, Parringtonia has a foramen or hole on the outer surface of the maxilla. The scapula of Parringtonia differs in that it has a small bump or tubercle over its shoulder socket. Both Parringtonia and Erpetosuchus have a groove that runs along the top of the neural arch of each vertebra.[1]
When first described by Friedrich von Huene in 1939, Parringtonia was assigned to a group called Pseudosuchia, which included crocodile-like Triassic archosaurs (although the name has recently been reinstated for the clade including all crocodile-line archosaurs).[2] In 1970 and 1976, Parringtonia was referred to the family Erpetosuchidae because of similarities between its scapula and that of the better known Erpetosuchus.[3][4] In both genera, the scapula is very thin and forward-curving. Parringtonia and Erpetosuchus are similar in size, and the osteoderms of both genera are similar in shape and sculpture. However, the osteoderms of Parringtonia are comparable to a number of other small archosaurs and cannot diagnose it as an erpetosuchid alone. Since Parringtonia lacks all of the autapomorphies or unique characteristics of Erpetosuchus including an otic notch at the back of the skull and a large antorbital fenestra set in a deep fossa on the snout, its classification as an erpetosuchid was tentative at first.[5]