Hi everyone! I’ve been researching for a bunch of manuscripts all this past spring. Check out this new preprint on the ornithomimosaur materials from the Arundel Formation:
Additionally, I regard the Utah taxon Nedcolbertia justinhofmanni as an intermediate non-ornithomimid/deinocheirid ornithomimosaur. It shares a single flexor fossa on its pedal unguals and anteroposteriorly short phalanges from pedal digit IV with ornithomimosaurs (Brownstein, 2016) (listed as synapomorphies of the group by Choiniere, Foster & De Klerk (2012)). It also has metatarsals more elongate in form than tyrannosaurs and a proximally pinched metatarsal III.
What’s interesting to me is that the shape of metatarsal III of the Arundel form suggests that it had a more derived metatarsus condition than Nedcolbertia. I use this and a temporal comparison of the formations in which Nedcolbertia, the Arundel taxon, and what I believe to be its close relative (Kinnareemimus) to support my theory that ornithomimosaurs with different metatarsus conditions coexisted in North America (Brownstein, 2016). Unfortunately, the paucity of decent North American ornithomimosaur material from the Early Cretaceous of North America makes any analysis of possible ecological interactions between ornithomimosaur lineages ill-informed (Brownstein, 2016). It is interesting to note, however, that Nedcolbertia can be differentiated by many ornithomimosaurs by its manal morphology and simplistic and pneumatic dorsal vertebra (Kirkland et al., 1998).
All in all, the Arundel dinosaur fauna is in serious need of more research. If there’s any dinosaur researcher out there looking for something to study, the Early Cretaceous dinosaurs of Maryland are just another opportunity to be found in the eastern United States and Canada.
EDIT: Just fixed some reference formats and added a figure showing the metatarsals. Oh well. New version will be out soon.
- Brownstein CD. 2016. Redescription of Arundel formation Ornithomimosaur material and a reinterpretation of Nedcolbertia justinhofmanni as an “Ostrich Dinosaur”: Biogeographic implications. PeerJ Preprints 4:e2308v1.
Choiniere JN, Forster CA & De Klerk WJ. 2012. New information on Nqwebasaurus thwazi, a coelurosaurian theropod from the Early Cretaceous Kirkwood Formation in South Africa. Journal of African Earth Sciences 71–72: 1–17.
Kirkland JI, Whittle CH, Britt BB, Madsen S, Burge D. 1998. A Small Theropod from the Basal Cedar Mountain Formation (Lower Cretaceous, Barremian) of Eastern Utah. In Lucas SG, Kirkland JI & Estep JW, eds:Lower and Middle Cretaceous Terrestrial Ecosystems. New Mexico Museum of Natural History and Science Bulletin 14: 239-248.