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Erpetosuchidae
Erpetosuchidae is an extinct family of pseudosuchian archosaurs. Erpetosuchidae was named by D. M. S. Watson in 1917 to include ''Erpetosuchus''. It includes the type species ''Erpetosuchus granti'' from the Late Triassic of Scotland, ''Erpetosuchus'' sp. from the Late Triassic of eastern United States and ''Parringtonia gracilis'' from the middle Middle Triassic of Tanzania; the group might also include ''Dyoplax arenaceus'' from the Late Triassic of Germany.
==Description==
Three synapomorphies or shared characteristics were identified for Erpetosuchidae: teeth restricted to the anterior half of the maxilla, a posterior half of the maxilla that is thicker than it is tall, and no tooth serrations. Other possible synapomorphies of the two taxa not yet sampled in the cladistic analysis were considered tentative. Both taxa share a sharp ridge on the lateral margin of the maxilla that marks the ventral extent of the antorbital fossa. Ventral to this ridge, the external surface of the maxilla is inclined medially towards the alveolar margin. In ''Erpetosuchus'', this medially inclined external surface of the maxilla continues posteriorly onto the jugal, exposing much of the external surface of the jugal in ventral view. This morphology unites the North American and European specimens of ''Erpetosuchus'' with ''Parringtonia gracilis''. Other potential synapomorphies include a hypertrophied tuber hypothesized for the attachment of the m. triceps brachii on the posterolateral surface of the proximal scapula blade. Unlike other archosauriforms that have a small tuber in the same location, the size of the tuber in erpetosuchids is exceptionally large in relation to the overall size of the scapula. Furthermore, as Krebs (1976) hypothesized the scapula blade slightly arc anteriorly in both taxa. However, this condition is similar to that of other archosaurs, like ''Postosuchus kirkpatricki''. Both ''Parringtonia'' and ''Erpetosuchus'' have a groove that runs along the top of the neural arch of each vertebra.〔
While ''Erpetosuchus granti'' and ''Erpetosuchus'' sp. are nearly indistinguishable, the scapula of ''Parringtonia'' differs from ''E. granti'' in that it has a small bump or tubercle over its shoulder socket, osteoderms that are nearly square instead of being anteroposteriorly longer than wide, and a foramen (or hole) on the outer surface of the maxilla. ''Parringtonia'' has five tooth sockets, ''Erpetosuchus gracilis'' only four, and ''Erpetosuchus'' sp. six or more (up to nine). Furthermore, ''Erpetosuchus'' sp. has a proportionally taller ascending process of the maxilla than ''Parringtonia''.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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