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The first complete description of the holotype of Brachylophosaurus canadensis Sternberg, 1953 (Dinosauria: Hadrosauridae) with comments on intraspecific variation



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    1. Department of Earth Sciences, Carleton University, 2125 Herzberg Building, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6
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    1. Department of Biological Sciences, University of Alberta, CW 405 Biological Sciences Building, Edmonton, Alberta, Canada T6G 2E9
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Current address: Department of Biological Sciences, University of Calgary, 2500 University Drive, Calgary, Alberta, Canada T2N 1N4. E-mail:


The holotype of Brachylophosaurus canadensis was collected by C.M. Sternberg in 1936 from the Oldman Formation (Upper Cretaceous) of Alberta, Canada, with a brief description focusing on the cranium following in 1953. A re-description of the holotype skeleton confirms its position as a hadrosaurine dinosaur exhibiting the following unique combination of characters: paddle-like solid nasal crest; posteriorly elongated prefrontal; only the anterior tip of the lacrimal contacting maxilla; extremely elongated anterior maxillary process; and a quadratojugal with a noncrescentic posterior margin variably forming a paraquadratic foramen with the quadrate. Comparison of the holotype with other specimens assigned to the taxon reveals numerous morphological differences. These variable features include the presence/absence of an accessory premaxillary foramen, the number of maxillary/dentary vertical tooth rows, the number of functional teeth per tooth row contributing to the dental occlusal surface, the bones forming the mandibular glenoid, the presence/absence of a nasal foramen, nasal crest morphology, the number of cervical vertebrae, and axis morphology.

© 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 159, 373–397.