Osteology of the type material of Melanorosaurus readi, a ‘near sauropod’ (Dinosauria: Sauropodomorpha) from the Late Triassic lower Elliot Formation of South Africa, and the status of referred specimens

Nair, Jay P. and Yates, Adam M. (2014). Osteology of the type material of Melanorosaurus readi, a ‘near sauropod’ (Dinosauria: Sauropodomorpha) from the Late Triassic lower Elliot Formation of South Africa, and the status of referred specimens. In: Society of Vertebrate Paleontology, Seventy-fourth annual meeting, Programs and Abstracts. Society of Vertebrate Paleontology, Seventy-fourth annual meeting, Estrel Berlin, Berlin, Germany., (193-194). 5– 8 November 2014.

Author Nair, Jay P.
Yates, Adam M.
Title of paper Osteology of the type material of Melanorosaurus readi, a ‘near sauropod’ (Dinosauria: Sauropodomorpha) from the Late Triassic lower Elliot Formation of South Africa, and the status of referred specimens
Conference name Society of Vertebrate Paleontology, Seventy-fourth annual meeting
Conference location Estrel Berlin, Berlin, Germany.
Conference dates 5– 8 November 2014
Proceedings title Society of Vertebrate Paleontology, Seventy-fourth annual meeting, Programs and Abstracts
Publication Year 2014
Sub-type Published abstract
Volume 33
Issue Supplement
Start page 193
End page 194
Total pages 2
Language eng
Keyword Melanorosaurus
Sauropodmorpha
Sauropoda
Dinosaur
Late Triassic
South Africa
Osteology
Q-Index Code EX
Q-Index Status Provisional Code
Institutional Status Unknown
Additional Notes The Late Triassic Norian stage was an important time in the radiation of sauropodomorph dinosaurs, when phylogenetically disparate taxa began to increasingly co-exist in time and space globally. A diversity of sauropodomorphs yielded from the lower Elliot Formation of southern Africa exemplify this, where six presently valid taxa and at least two unnamed forms represent variety in body size, cursoriality and postural gait, and probable feeding capacity. Accordingly, these provide key insights into the non-sauropod to sauropod evolutionary transition. Despite being founded on an accumulation of cursorily described postcranial elements, Melanorosaurus readi is presently the best-understood African Norian sauropodomorph due to two relatively complete specimens described and referred to it. However, the lack of a detailed osteological account of the type material renders the subsequent specimen referrals problematic, which may in future hinder proper assessment of any additional lower Elliot sauropodomorph materials. Our survey of the type repository of M. readi (93 elements) demonstrates an abundance of extraneous fragmentary basal sauropodomorph specimens that were not part of the syntypes originally described by Sydney Haughton in 1924. We show, via systematic preservational qualities, historical details, and osteological data, that these extraneous materials represent at least three additional unnamed sauropodomorphs. The revised lectotype and paralectotypes of M. readi allow for a differential diagnosis of the taxon, and bear several traits observable in the referred specimens: (1) primordial sacral II transverse processes with paired fossae; (2) unexpanded hyposphenal ridges present on proximal caudals; (3) an embayment on the distal end of fibula. Although still incomplete, sacral materials in the lecto-paralectotype suggest a four-vertebral sacrum, as per both referred specimens. A newly identified braincase is part of previously described referred material of Melanorosaurus that until now had only been known from postcranial elements. It exhibits (1) a partially separated vagal canal, (2) the near loss of the crista tuberalis, and (3) a relatively large and caudally tapering floccular recess, which are features shared with the neurocranium of a recently described complete skull of Melanorosaurus. Overall, and despite minor distinctions, an osteological revision of the type material of M. readi, in combination with the new braincase, seems to increase support for all these specimens belonging to one taxon.

Document type: Conference Paper
Collection: School of Biological Sciences Publications
 
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Created: Fri, 11 Mar 2016, 16:05:17 EST by Jay Nair on behalf of School of Biological Sciences