Creature Feature 11

Hello, fans! Today, I'd like to talk a bit about the Nodosaur from Hell Creek - Denversaurus (or Edmontonia ?) schlessmani.

Denversaurus (=Edmontonia?) schlessmani model, work in progress.

Denversaurus schlessmani was a stocky, quadrupedal ornithischian dinosaur, somewhat similar in build to Ankylosaurus. While the two share some overall similarities, they belong to different clades within Ankylosauria. Where Ankylosaurus is in the family Ankylosauridae, Denversaurus is placed in Nodosauridae. Nodosaurs are distinct from Ankylosaurs in several ways. Nodosaurs had proportionally longer snouts, shorter, narrower beaks, and lacked the notorious 'clubs' of Ankylosaurs. Instead, the most distinctive feature of their armor was the large spikes, particularly those protruding from the shoulder region. Additionally, Nodosaurs did not possess the large squamosal plates found in Ankylosaurs.

Currently, it is not completely certain whether or not Denversaurus schlessmani represents a distinct genus, as some sources believe it to be synonymous with Edmontonia (Hunt and Lucas, 1992). The original description based the distinct status of the taxon on the fact that the back of the skull was much wider than in Edmontonia specimens (Bakker, 1988), but later analysis showed that this was actually due to crushing of the remains (Carpenter, 1990), and the species was actually a junior synonym of Edmontonia longiceps (Vickaryous et al., 2004). However, a recent reevaluation of late Cretaceous Nodosaurids supports Denversaurus schlessmani as a distinct taxon based on its phylogenetic position within the group (Burns, 2015).

Current estimates on the size of Denversaurus schlessmani put its length at approximately six meters, and its weight at 3 tonnes (Paul, 2010).

I hope you enjoyed today's Creature Feature! I'm sorry that I didn't have all that much to write, as there is not a ton of information on Denversaurus that I could find. I did what I could, though, and I hope you at least learned something new about this rather interesting creature!

Acknowledgements:

Hunt, A.P. and Lucas, S.G., 1992. Stratigraphy, Paleontology and age of the Fruitland and Kirkland Formations (Upper Cretaceous), San Juan Basin, New Mexico. New Mexico Geological Society Guidebook, 43rd Field Conference, San Juan Basin. Volume 4: 217-240

Bakker, R.T. 1988. Review of the Late Cretaceous nodosauroid Dinosauria: Denversaurus schlessmani, a new armor-plated dinosaur from the Latest Cretaceous of South Dakota, the last survivor of the nodosaurians, with comments on Stegosaur-Nodosaur relationships. Hunteria 1(3):1-23.

Carpenter, K. 1990. Ankylosaur systematics: example using Panoplosaurus and Edmontonia (Ankylosauria: Nodosauridae), In: Carpenter, K. & Currie, P.J. (eds) Dinosaur Systematics: Approaches and Perspectives. Cambridge University Press, Cambridge: 281-298

Vickaryous, M.K.; Maryanska, T.; Weishampel, D.B. 2004. Ankylosauria. In: Weishampel, D. B.; Dodson, P.; Osmólska, H. (eds.). The Dinosauria (Second Edition). University of California Press. 363-392.

Burns, M.E. Intraspecific Variation in Late Cretaceous Nodosaurids (Ankylosauria: Dinosauria). Journal of Vertebrate Paleontology, Program and Abstracts, 2015: 99–100.

Paul, G.S. 2010. The Princeton Field Guide to Dinosaurs. Princeton University Press.