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A new specimen of the T riassic pistosauroid Y unguisaurus , with implications for the origin of P lesiosauria ( R eptilia, S auropterygia)
Author(s) -
Sato Tamaki,
Zhao LiJun,
Wu XiaoChun,
Li Chun
Publication year - 2014
Publication title -
palaeontology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.69
H-Index - 63
eISSN - 1475-4983
pISSN - 0031-0239
DOI - 10.1111/pala.12048
Subject(s) - biology , anatomy , ontogeny , holotype , zoology , genetics , taxonomy (biology)
An adult skeleton of the pistosauroid sauropterygian Y unguisaurus liae reveals a number of morphological features not observed in the holotype, such as the complete morphology of the skull roof, stapes, atlas and axis, ventral view of the postcranium, and nearly complete limbs and tail. Size and morphological differences between the two specimens are mostly regarded as ontogenetic variation, and newly added data did not affect the phylogenetic relationships with other pistosauroids significantly. The number of mesopodia (11 carpals and 8 tarsals) exceeds that known in any other T riassic marine reptiles and does not serve as a precursor of the plesiosaurian pattern with fewer mesopodia of different topology; it demonstrates variability of the limb morphology among the T riassic pistosauroids. The pectoral girdles of C orosaurus , A ugustasaurus and Y unguisaurus may indicate early stages of the adaptation towards the plesiosaurian style of paraxial limb movements with ventroposterior power stroke.