Friday 30 May 2014

A Megatheropod tooth from the Early Cretaceous of Guanxi Province, China.

In recent years China has become a focus for studies of Early Cretaceous terrestrial ecosystems, with a large number of finds from deposits such as the Jehol Biota that have revolutionised our understanding of many organisms during the period, particularly Insects and small Vertebrates. However fossils of larger Vertebrates from the Early Cretaceous of China remain rare, and in particular large Theropods (which are likely to have been present) are very poorly known from China at this time.

In a paper published in the journal Acta Geologica Sinica in February 2014, Mo Jinyou, Huang Choalin and Xie Shaowen of the Natural History Museum of Guanxi and Eric Buffetaut of the Laboratoire de Geologie de l’Ecole Normale Superieure describe the tooth of a large Theropod Dinosuar from the Early Cretaceous Xinlong Formation of the Napai Basin in Fusui County in Guanxi Province.

The tooth appears to be a right maxillary or left dentary. It is almost complete, with only the tip, part of the crown and the root missing. It is 71 mm high, 37 mm deep and 17 mm wide, with a curved, bladelike shape, typical of Theropod teeth. There are distinct carinae (serrations) on both surfaces, again typical of Theropod teeth. Mo et al. believe that it is most likely to have originated from a large Carcharodontosaurid (a group related to Allosuarid and Neovenatorids).

Gigantic Theropod tooth from the Xinlong Formation of the Napai Basin in Fusui County, Guangxi Province, in labial (A & B), basal (C), lingual (D & G), distal (E) and mesial (F) views. Arrow in (B & D) marks the end of the mesial carina. Scale bars are 1 mm in (A & G) and 10 mm in all other photos. Mo et al. (2014).

The depth (front-to-back) measurement of this tooth is exceptionally large, with only three known Theropods producing larger teeth; the largest tooth recorded in a Tyranosaurus was 54.5 mm deep, the largest tooth of a Carcharodontosaurus 46.65 mm deep and the largest tooth of an Acrocanthosuarus was 42.07 mm deep. This suggests that whatever produced the Xinlong tooth was likely to have been an exceptionally large Theropod Dinosaur.

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