Cedarpelta
| Cedarpelta | |
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| File:Euoplocephalus.JPG | |
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| Genus: | Cedarpelta
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| Species: | C. bilbeyhallorum
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| Binomial name | |
| Cedarpelta bilbeyhallorum Carpenter et al., 2001
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Cedarpelta bilbeyhallorum is the most basal known nodosaurid anklyosaur (Nodosauridae; Ankylosauria), based on material recovered from the Early Cretaceous of North America. Of all nodosaurids described so far, it is the only taxon known to lack extensive cranial ornamentation, a trait which has been interpreted as plesiomorphic for the Nodosauridae. Carpenter et. al. (2001) diagnose Cedarpelta by the presence of a rostrocaudally elongate pterygoid with a caudolaterally oriented, trochlear-like process, a premaxilla with six conical teeth, an unpaired parietal, and a straight ischium. Two skulls are known, and the skull length for Cedarpelta is estimated to have been roughly 60 cm. Signifantly, one of the Cedarpelta skulls was found disarticulated, a first for an ankylosaur skull, allowing paleontologists a unique opportunity to examine the individual bones instead of being limited to a cossified unit. The etymology of this binomen may be read as "Bilbey and Hall's Cedar (Mountain) shield," with the genus named for the Cedar Mountain Formation and the animal's armored plates and the species named for Sue Ann Bilbey and Evan Hall, discoverers of the type locality.
All material referrable to Cedarpelta has been recovered from the Ruby Ranch Member of the Cedar Mountain Formation (Berriasian-Hauterivian) of eastern Utah.
Holotype
Carpenter et. al. (2001) designated CEUM 12360 as the holotype specimen of Cedarpelta bilbeyhallorum (CEUM is the acronym of the College of Eastern Utah Prehistoric Museum in Price, Utah). CEUM 12360 consists of an articulated, incomplete skull lacking the snout and mandibles. Carpenter et. al. (2001) also designated a long list of paratype material, mostly isolated bones that could be referred to Cedarpelta bilbeyhallorum.
Phylogenetics
Cedarpelta bilbeyhallorum was believed by Carpenter et. al. (2001) to be closely related to Gobisaurus domoculus of north-central China and Shamosaurus scutatus of Mongolia, and they placed the taxon within the Familiy Ankylosauridae. Vickaryous et. al. (2004), however, interpreted the genus as the basalmost member of the Family Nodosauridae, most closely related to the nodosaurids Pawpawsaurus campbelli, Silvisaurus condrayi, and Sauropelta edwardsorum.
References
- Carpenter, K., Kirkland, J. I., Birge, D., and Bird, J. 2001. Disarticulated skull of a new primative anklyosaurid from the Lower Cretaceous of Utah. in Carpenter, K. (editor) 2001. The Armored Dinosaurs. Indiana University Press
- Vickaryous, Maryanska, and Weishampel 2004. Chapter Seventeen: Ankylosauria. in The Dinosauria (2nd edition), Weishampel, D. B., Dodson, P., and Osmólska, H., editors. University of California Press.