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Paleoneurological evidence against a proboscis in the sauropod dinosaur Diplodocus

A new paper of my colleague and excellent paleontologist Fabien Knoll:

Fabien Knoll, Peter M. Galton and Raquel López-Antoñanzas. Paleoneurological 
evidence against a proboscis in the sauropod dinosaur Diplodocus. Geobios, In 
Press, Corrected Proof, Available online 20 January 2006

The dinosaur Diplodocus has a single, relatively large external bony narial 
orifice that is positioned far back between the orbits. In some mammals, such 
as elephants and tapirs, the caudal position of the narial opening is 
associated with a proboscis, so it has been suggested that Diplodocus possibly 
also had a trunk. In elephants, the facial nerve is large as it emerges from 
the brain. A branch of this nerve and a branch of the trigeminal nerve unite to 
form the proboscidial nerve that supplies the muscles of the powerful and 
complex motor system of the trunk. In contrast to the situation in modern 
elephants, the absolute as well as the relatively small size of the facial 
nerve in Diplodocus (deduced from an endocranial cast) indicates that there is 
no paleoneuroanatomical evidence for the presence of an elephant-like proboscis 
in this genus.


Jose Ignacio Ruiz-Omeñaca
Departamento de Ciencias de la Tierra
Area de Paleontologia
Universidad de Zaragoza

tel: (+34) 976 761000 ext. 3160
fax: (+34) 976 761106
e-mail: jigruiz@unizar.es