Lotosaurus adentus Zhang, 1975

Nesbitt, Sterling J., 2011, The Early Evolution Of Archosaurs: Relationships And The Origin Of Major Clades, Bulletin of the American Museum of Natural History 2011 (352), pp. 1-292 : 29

Lotosaurus adentus Zhang, 1975

AGE: Middle Triassic ( Zhang, 1975).

OCCURRENCE: Batung Formation, Hunan Province, China ( Zhang, 1975).

HOLOTYPE: Unspecified, either IVPP V4880 or V4881.

REFERRED MATERIAL: IVPP V 48013 , skull, articulated and disarticulated remains

of at least?10 individuals from a monotypic bonebed (unnumbered).

REMARKS: Lotosaurus is a highly specialized archosaur from the Middle Triassic of China with elongated neural spines forming a sail, robust fore- and hind limbs, and a peculiar skull with an edentulous beak. In a preliminary description, Zhang (1975) noted that Lotosaurus may be related to other archosaur taxa with elongated neural spines (e.g., Ctenosauriscus ) and others have followed this line of thought (e.g., Carroll, 1988). Nesbitt (2007) went further and described some of the features Lotosaurus shared with taxa such as Arizonasaurus and Effigia and found Lotosaurus to be closely related to these taxa in a position just outside ‘‘clade Y’’ (5 Shuvosauridae ). As explained by Nesbitt (2007), if Lotosaurus is more closely related to Shuvosaurus and Effigia than to Arizonasaurus , the ctenosauriscids (as proposed by Nesbitt, 2005a) would be paraphyletic. A full description of Lotosaurus is currently underway.

Lotosaurus differs from all other archosaurs by the combination of a sail formed from the elongation of the neural spines of the presacral vertebrae and the presence of edentulous premaxillae, maxillae, and dentaries.

KEY REFERENCES: Zhang, 1975; Nesbitt, 2007.