Ankylosaur week, day 1: Hungarosaurus

My to-do list has once again reached epic proportions, and includes three technical projects that now need urgent attention, about ten editorial jobs that need to be dealt with, several overdue book reviews, a lot of consultancy work, and a book synopsis. Plus of course this is all done in 'spare time' given family life and the day-job. In an effort to catch up with this back-log I'm going to let Tet Zoo lay fallow for a week, sort of. We haven't really had enough dinosaurs on Tet Zoo lately and, frankly, most of the stuff that I have lined up for the near future isn't on dinosaurs either, so what I'm going to do is post a series of very short articles (one per day) over the length of the week. And, for no particular reason other than that I haven't done much on them to date, all of the articles are going to be on the quadrupedal armoured ornithischian dinosaurs: the ankylosaurs. All of these pieces have been written in advance - they're all cannibalised from the dinosaur field guide I discussed a while back in the Tet Zoo field guide to ostrich dinosaurs, so won't take up time. So here's part 1, revisit tomorrow for part 2.

We begin with the nodosaurid Hungarosaurus tormai, the most complete Upper Cretaceous ankylosaur yet reported from Europe. Described in 2005 by Attila Ösi, Hungarosaurus is known from four specimens discovered in 2001 and 2003 in an open-pit bauxite mine in the Hungarian Bakony Mountains (Ösi 2005). The fossils come from the Santonian Csehbánya Formation and were discovered alongside remains of lizards, azhdarchid pterosaurs, small theropods and a Rhabdodon-like iguanodontian. Elements from most of the skeleton have been discovered, including a substantial amount of skull material. Literally hundreds of Hungarosaurus bones are known. These show that Hungarosaurus was approximately 4 m long and that it had teeth at the tip of its upper jaw (a primitive character among ankylosaurs), but was unusual in possessing a U-shaped notch at the upper jaw's tip and in having bony bosses on its postorbital and quadratojugal bones. These would have been enlarged in life by keratinous coverings and may have functioned in display and combat.

The vertebrae that formed the anterior part of its dorsal column were unusually wide and its lower leg was comparatively long (for a nodosaurid). Keeled armour plates were arranged in two rings across the neck and oval-shaped keeled scutes covered much of the body and tail. A large crescentic plate covered the hip region, the concave margin of which was probably closest to the tail, and two conical spikes, one on each side, projected upwards from either side of this concave edge. A phylogenetic analysis of Hungarosaurus indicates that it was a basal nodosaurid less derived than Sauropelta and Silvisaurus (Ösi 2005).

The Hungarosaurus material is kept at the Hungarian Natural History Museum, Budapest, and I assume that the skeletal reconstruction shown here is on display at that institution.

Ref - -

Ösi, A. 2005. Hungarosaurus tormai, a new ankylosaur (Dinosauria) from the Upper Cretaceous of Hungary. Journal of Vertebrate Paleontology 25, 370-383 [available, free, here].