Tatisaurus

*Tatisaurus oehleri*

**Tatisaurus** is a genus of ornithischian dinosaur from the Early Jurassic from the Lower Lufeng Formation in Yunnan Province in China. Little is known as the remains are fragmentary.

## Discovery and species

In 1948 and 1949 Father Edgar Oehler, a catholic priest working for the Fu Jen Catholic University at Beijing, excavated fossils near the village of Da Di in Yunnan. Among them was a jaw bone of a herbivorous dinosaur. In 1965 David Jay Simmons named and described it as the type species *Tatisaurus oehleri*. The generic name is derived from Da Di, then more usually spelled as "Ta Ti". The specific name honours Oehler. The holotype, FMNH CUP 2088, was found in the Zhangjiawa Beds of the Lufeng Formation, dating from the Sinemurian. It consists of a partial left mandible with teeth. The lower jaw bone fragment is, lacking the tip, six centimetres long. The teeth are eroded. It is the only specimen known of the species.

Simmons assigned *Tatisaurus* to the Hypsilophodontidae, though this group was seen by him as an evolutionary grade of "primitive" Ornithopoda, ancestral to several ornithischian groups; he felt that *Tatisaurus* 's affinities were with *Scelidosaurus* or the Ankylosauria. Later, in 1990, the specimen was reviewed by Dong Zhiming who noted it had similarities with *Huayangosaurus* and placed it in the same subfamily, the Huayangosaurinae, hence making it a stegosaurian.

Later still, in 1996, Spencer Lucas reclassified *Tatisaurus* as a member of the genus *Scelidosaurus*, thus as a *S. oehleri*, in order to use it for a biochron. This has in 2007 been regarded by David B. Norman and colleagues as unfounded. They instead consider *Tatisaurus* to be a dubious basal thyreophoran, showing the thyreophorean synapomorphy of a ventrally deflected mesial end of the dentary. It would then be one of the oldest known Thyreophora.

## Description

The type species, Tatisaurus oehleri , was described in 1965 by Simmons, based on only a partial left jaw with teeth. The remains come from the Deep Red Bed, part of the Lufeng Formation, in Yunnan, China, near the village of Dadi from which the generic name comes.

Simmons thought it was related to primitive hypsilophodontids, although it had some characteristics of an ankylosaurian. Later, in 1990, the specimen was reviewed by Dong Zhiming, who noted that it had similarities to Huayangosaurus and placed it in the same family, thus making it a stegosaurus. In a more modern study, in 1996, Tatisaurus was reclassified by Lucas as a member of the genus Scelidosaurus . This has been noted by David B. Norman et al. as unfounded. Instead they consider it a doubtful basal Thyreophora, although it is considered to be not far removed from its ancestor Fabrosaurus .

## JPInstitute.com Description

Tatisaurus was a plant-eater that lived in China near the beginning of the Jurassic period. Since only a lower jaw and teeth were found, not much is known of this dinosaur. It might be related to Stegosaurus or even Ankylosaurus. It may even be an animal that is related to both, and early ancestor of both families.

The discussion of where to place Tatisaurus is still going on. It may be a basal animal that eventually branched out into both stegosaurs and ankylosaurs.

## Links

https://web.archive.org/web/20030813035859/http://www.jpinstitute.com/dinopedia/dinocards/dc\_tatis.html#