Diagnostic characteristics for the Nodosauridae include the following: supraorbital boss rounded protuberance, occipital condyle derived from only the basioccipital and ornamentation present on the premaxilla. There is a fourth ambiguous character: the acromion is a knob-like process. All nodosaurids, like other ankylosaurs, may be described as medium-sized to large, heavily-built quadrapedalherbivorousdinosaurs, possessing small denticulate teeth and parasagittal rows of osteoderms (a type of armour) on the dorsolateral surfaces of the body.
The clade Nodosauridae was first defined by Paul Sereno in 1998 as "all ankylosaurs closer to Panoplosaurus than to Ankylosaurus," a definition followed by Vickaryous, Maryanska, and Weishampel in 2004. Vickaryous et al. considered two genera of nodosaurids to be of uncertain placement (incertae sedis): Struthiosaurus and Animantarx, and considered the most primitive member of the Nodosauridae to be Cedarpelta.1
References
^ Vickaryous, M. K., Maryanska, T., and Weishampel, D. B. (2004). Chapter Seventeen: Ankylosauria. in The Dinosauria (2nd edition), Weishampel, D. B., Dodson, P., and Osmólska, H., editors. University of California Press.
Carpenter, K. (2001). "Phylogenetic analysis of the Ankylosauria." In Carpenter, K., (ed.) 2001: The Armored Dinosaurs. Indiana University Press, Bloomington & Indianapolis, 2001, pp. xv-526
Osi, Attila (2005). Hungarosaurus tormai, a new ankylosaur (Dinosauria) from the Upper Cretaceous of Hungary. Journal of Vertebrate Paleontology 25(2):370-383, June 2003.