Saturday, April 09, 2016

Yuanansuchus maopingchangensis: a new Capitosauroid Temnospondyl From Middle Triassic China

Yuanansuchus maopingchangensis sp. nov., the second capitosauroid temnospondyl from the Middle Triassic Badong Formation of Yuanan, Hubei, China




A second species of Yuanansuchus, Y. maopingchangensis, is erected for new temnospondyl material from the Maopingchang site, Yuanan County, Hubei Province, China. These specimens are from the same horizon that produced Y. laticeps, the type species. Y. maopingchangensis shares the following features with Y. laticeps: postorbital portion of skull occupied more than 1/3 of skull length; tabular horn directed laterally; lateral line sulci continuous, well impressed; supraorbital sensory canal enters lacrimal; preorbital projection of jugal less than half length of snout; and vomerine plate short. However, Y. maopingchangensis differs from Y. laticeps in having an elongated skull, frontal extending posteriorly to the level of the posterior orbital margin, closed otic fenestra, cultriform process of parasphenoid extending to the level of the anterior margin of the interpterygoid vacuities, and absence of fodina vomeralis. Analysis of a new capitosaur phylogenetic data matrix, containing 56 characters and 29 species, confirms that the two species from Yuanan are sister taxa and that Capitosauroidea can be divided into two major clades: one including Parotosuchus, Eryosuchus, Calmasuchus and Cherninia, and another including Mastodonsaurus, Yuanansuchus, Stanocephalosaurus, Procyclotosaurus, Paracyclotosaurus, Antarctosuchus, Eocyclotosaurus, Quasicyclotosaurus, Tatrasuchus and Cyclotosaurus.

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