A new species of Largocephalosaurus (Diapsida: Saurosphargidae), with implications for the morphological diversity and phylogeny of the group. (January 2014)

• Record Type: Journal Article
• Authors: LI, CHUN; JIANG, DA-YONG; CHENG, LONG; WU, XIAO-CHUN; RIEPPEL, OLIVIER
• Is Part Of: Geological magazine. Volume 151:Number 1(2014:Jan.)
• Page Start: 100
• Page End: 120
• Publication Date: 2014-01
• Subjects: Geology -- Periodicals; 551.05
• DOI: 10.1017/S001675681300023X
• Languages: English
• ISSNs: 0016-7568

Abstract

<abstract abstract-type="normal"> <title>Abstract</title> <p> <italic>Largocephalosaurus polycarpon</italic> Cheng <italic>et al</italic>. 2012<italic>a</italic> was erected after the study of the skull and some parts of a skeleton and considered to be an eosauropterygian. Here we describe a new species of the genus, <italic>Largocephalosaurus qianensis</italic>, based on three specimens. The new species provides many anatomical details which were described only briefly or not at all in the type species, and clearly indicates that <italic>Largocephalosaurus</italic> is a saurosphargid. It differs from the type species mainly in having three premaxillary teeth, a very short retroarticular process, a large pineal foramen, two sacral vertebrae, and elongated small granular osteoderms mixed with some large ones along the lateral most side of the body. With additional information from the new species, we revise the diagnosis and the phylogenetic relationships of <italic>Largocephalosaurus</italic> and clarify a set of diagnostic features for the Saurosphargidae Li <italic>et al</italic>. 2011. <italic>Largocephalosaurus</italic> is characterized primarily by an oval supratemporal fenestra, an elongate dorsal 'rib-basket', a narrow and elongate transverse process of the dorsal vertebrae, and the lack of a complete dorsal carapace of osteoderms. The Saurosphargidae is distinct mainly in having a retracted external naris, a jugal–squamosal contact, a large supratemporal extensively contacting the quadrate shaft, a leaf-like tooth crown with convex labial surface and concave lingual surface, a closed dorsal 'rib-basket', many dorsal osteoderms, a large boomerang-like or atypical T-shaped interclavicle. Current evidence suggests that the Saurosphargidae is the sister-group of the Sauropterygia and that <italic>Largocephalosaurus</italic> is the sister-group of the <italic>Saurosphargis</italic>–<italic>Sinosaurosphargis</italic> clade within the family.</p> </abstract>