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Hadrosaurus and Claosaurus revised diagnoses



From: Ben Creisler
bh480@scn.org

I don't recall seeing this new article mentioned yet, so 
just in case:

ALBERT PRIETO-MÁRQUEZ (2011)
Revised diagnoses of Hadrosaurus foulkii Leidy, 1858 (the 
type genus and species of Hadrosauridae Cope, 1869) and 
Claosaurus agilis Marsh, 1872 (Dinosauria: Ornithopoda) 
from the Late Cretaceous of North America  
Zootaxa 2765: 61?68 (15 Feb. 2011) 
http://www.mapress.com/zootaxa/2011/f/z02765p068f.pdf


Hadrosauridae constitutes a very diverse clade of 
herbivorous dinosaurs that were extremely abundant during 
the Campanian?Maastrichtian (Late Cretaceous) of Europe, 
Asia, both Americas, and probably also Antarctica (Horner 
et al. 2004). The fact that hadrosaurids are one of the 
best-known clades of dinosaurs, represented by arguably 
the richest dinosaurian fossil record, contrasts with the 
scarcity of material and apparently undiagnostic nature 
of their type genus and species, Hadrosaurus foulkii. The 
holotype and only known specimen of H. foulkii is also 
historically significant for being the first skeletal 
remains of a dinosaur described outside Europe (Leidy 
1858). 
Recently, Prieto-Márquez et al. (2006) redescribed in 
detail the osteology of H. foulkii and revised the 
taxonomy of the genus  Hadrosaurus. These authors 
concluded that  H. foulkii is a nomen dubium because they 
found no autapomorphic or distinguishable characters in 
the type and only known materials of this taxon.
Here, I show that Hadrosaurus foulkii is actually 
diagnosable based on a combination of plesiomorphic and 
derived appendicular characters. An ancilliary outcome of 
this study is the recognition of a diagnostic combination 
of iliac characters (in the context of the phylogenetic 
framework of Prieto-Márquez 2010) in Claosaurus agilis, a 
poorly known hadrosauroid outgroup to Hadrosauridae (Fig. 
1) from the middle of the North American continent.