Tuesday, 10 May 2011

A Stunning Juvenile Tyrannosaurid

This was the talk of the palaeoworld and blogosphere late last night. Published on line last night in the latest Journal of Vertebrate Paleontology is the long awaited paper by Tsuihiji et al describing a wonderful example of a juvenile Tarbosaurus bataar from the Nemegt Formation in Mongolia. Expect copious amounts of coverage over the next few days and weeks and no doubt expect me to comment in the not too distant future.

Awesome material backed up by stunning digital rendering by the Witmer Lab. Here’s the abstract:



Abstract

A juvenile skull of the tyrannosaurid Tarbosaurus bataar found in the Bugin Tsav locality in the Mongolian Gobi Desert is described. With a total length of 290 mm, the present specimen represents one of the smallest skulls known for this species. Not surprisingly, it shows various characteristics common to juvenile tyrannosaurids, such as the rostral margin of the maxillary fenestra not reaching that of the external antorbital fenestra and the postorbital lacking the cornual process. The nasal bears a small lacrimal process, which disappears in adults. Lacking some of the morphological characteristics that are adapted for bearing great feeding forces in adult individuals, this juvenile specimen suggests that T. bataar would have changed its dietary niches during ontogeny. The numbers of alveoli in the maxilla (13) and dentary (14 and 15) are the same as those in adults, suggesting that they do not change ontogenetically in T. bataar and thus are not consistent with the hypothesis that the numbers of alveoli decreases ontogenetically in tyrannosaurids.

Reference

Tsuihiji, Takanobu , Watabe, Mahito , Tsogtbaatar, Khishigjav , Tsubamoto, Takehisa , Barsbold, Rinchen , Suzuki, Shigeru , Lee, Andrew H. , Ridgely, Ryan C. , Kawahara, Yasuhiro and Witmer, Lawrence M.(2011) 'Cranial osteology of a juvenile specimen of Tarbosaurus bataar (Theropoda, Tyrannosauridae) from the Nemegt Formation (Upper Cretaceous) of Bugin Tsav, Mongolia', Journal of Vertebrate Paleontology, 31: 3, 497 — 517 DOI: 10.1080/02724634.2011.557116

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