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Torosaurus is Triceratops

Paper is out in the new JVP: on the Taylor and Francis website:


Torosaurus Marsh, 1891, is Triceratops Marsh, 1889  (Ceratopsidae: 
Chasmosaurinae): synonymy through ontogeny

John B. Scannella; John R. Horner

Although they have been considered distinct genera for over a century,  
ontogenetic analyses reveal that Triceratops and âTorosaurusâ  actually 
represent growth stages of a single genus. Major changes in  cranial 
morphologyâincluding the opening of parietal fenestrae and the  elongation of 
the squamosalsâoccur rapidly, very late in Triceratops ontogeny and result in 
the characteristic 'Torosaurus'  morphology. This report presents the results 

a 10-year field study of  the dinosaurs of the Hell Creek Formation in Montana 
and is based on a  collection of over 50 specimens of Triceratops, including 
over 30  skulls, which have been amassed in that time, in addition to 
from numerous other North American museums. This large sample of  individuals 
reveals the full ontogenetic spectrum of Triceratops.  The synonymy of 
Triceratops and 'Torosaurus' contributes  to an unfolding view of extremely 
reduced dinosaur diversity just before  the end of the Mesozoic Era

Denver Fowler