13th June 2005
Michael P. Taylor
School of Earth and Environmental Sciences, University of Portsmouth, Portsmouth PO1 3QL, UK
In 1930, an expedition led by Frederick Migeod excavated a large sauropod dinosaur at Tendaguru, Tanzania. This specimen, BMNH R5937, has attracted surprisingly little study: it has been the subject of only one significant publication, and none of the material has been figured. Migeod's 1931 account described the specimen as ``of the Brachiosaurus type'', but also mentioned non-brachiosaurid features including bifurcated neural spines and ``wings'' in the anterior dorsals. If his interpretations are reliable, other proportions are also non-brachiosaurid, e.g. humeri only two thirds as long as the scapulocoracoid. The prepared material includes two dorsal and four cervical vertebrae, two further dorsal centra and an unidentified long-bone fragment. The cervicals are proportionally longer than in B. brancai. Unopened jackets contain additional material including at least three more cervical vertebrae, a ``wing'' from a dorsal, sacrals, a scapula and an ilium. Of the prepared material, the two dorsals are the best preserved, and probably represent D8 and D9. They have several laminae not usually associated with Brachiosaurus, including long, parallel spinoprezygapophyseal laminae and a configuration of the divided spinopostzygapophyseal laminae in which the median branches merge into a postspinal lamina and the lateral branches join the spinodiapophyseal laminae in a compound lateral lamina. However, lamination varies greatly along the dorsal column of the B. brancai type specimen, so comparing BMNH R5937 with it is difficult. The more complete dorsal column of Cetiosaurus oxoniensis also shows significant variation between adjacent dorsals, casting doubt on the widely assumed taxonomic informativeness of vertebral laminae.
[Note added 22nd September 2005: almost everything that I wrote about the distinctiveness of the BMNH R 5937 laminae is nonsense. See the slides for a much better diagnosis.]
This abstract is also available on the SVPCA web-site at http://svpca.org/years/2005_london/papers.htm
The entire abstracts volume for SVPCA 2005 can be downloaded from http://svpca.org/years/2005_london/53rd_SVPCA_abs.pdf [Local copy]