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Glishades ericksoni’, an indeterminate juvenile hadrosaurid from the Two Medicine Formation of Montana: implications for hadrosauroid diversity in the latest Cretaceous (Campanian-Maastrichtian) of western North America
Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.
University of Toronto.
Montana State University.
University of Toronto.
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2013 (English)In: Palaeobiodiversity and Palaeoenvironments, ISSN 1867-1594, Vol. 93, no 1, 65-75 p.Article in journal (Refereed) Published
Abstract [en]

Glishades ericksoni was named on the basis of partial paired premaxillae collected from the Late Campanian Two Medicine Formation of Montana, and was described as a non-hadrosaurid hadrosauroid. This interpretation of G. ericksoni has significant implications for hadrosauroid diversity and distribution because it represents the first occurrence of a non-hadrosaurid hadrosauroid in the Late Campanian of North America, and therefore implies either a prolonged period of sympatry between these forms and hadrosaurids or a biotic interchange with Asia. Given its small size, and therefore potential juvenile status, the taxonomic identity of G. ericksoni is re-evaluated here. Comparison with similarly-sized, taxonomically determinate, and coeval hadrosaurid specimens from the Two Medicine Formation (ProsaurolophusGryposaurus, andMaiasaura) suggest that the combination of characters used to distinguish G. ericksoni as a non-hadrosaurid hadrosauroid are more widely distributed or individually variable in hadrosaurids, or can be explained as the result of ontogenetic variation. In particular, the unique combination of characters used to diagnose G. ericksoni is also found in juvenile individuals of Prosaurolophus,Gryposaurus, and Maiasaura. Inclusion of juveniles of these taxa, scored on the basis of comparable anatomy, in the original phylogenetic analysis recovers the juvenile hadrosaurid specimens outside Hadrosauridae. Consequently, G. ericksoni cannot be confidently differentiated from a juvenile saurolophine, which are common in the upper and middle sections of the Two Medicine Formation, and is thus considered a nomen dubium. Given their absence in well-sampled Late Campanian and Maastrichtian deposits, non-hadrosaurid hadrosauroids appear to have been completely replaced by hadrosaurids in western North America by the Late Campanian.

Place, publisher, year, edition, pages
2013. Vol. 93, no 1, 65-75 p.
Keyword [en]
Hadrosauridae, Hadrosauroidea, Dinosaur systematics, Dinosaur diversity, Ontogeny
National Category
Zoology Evolutionary Biology
Research subject
Biology with specialization in Evolutionary Organismal Biology
URN: urn:nbn:se:uu:diva-217202DOI: 10.1007/s12549-012-0097-1ISI: 000319320900003OAI: oai:DiVA.org:uu-217202DiVA: diva2:692492
Available from: 2014-01-31 Created: 2014-01-31 Last updated: 2014-01-31Bibliographically approved

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Publisher's full texthttp://link.springer.com/article/10.1007%2Fs12549-012-0097-1

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Campione, Nicolas E.
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