Iguanacolossus & Hippodraco: Two New Iguanodonts

New Basal Iguanodonts from the Cedar Mountain Formation of Utah and the Evolution of Thumb-Spiked Dinosaurs. 2010. A. MacDonald, et al. PLoS ONE 5(11): e14075.

The Early Cretaceous of Utah has two new species of iguanodonts that are beaked herbivorous dinosaurs.

Iguanodonts are found all over the world in rocks dating to the Early Cretaceous Epoch (~145.5-99.6 million years ago). Their fossils are particularly abundant and diverse in Europe and east-central Asia with Europes Iguanodon being only the second formally named dinosaur in 1825.

Hippodraco scutodens (“horse-dragon, shield tooth”) (above) was found at a site north of Arches National Park. It lived approximately 124 million years ago, at the same time as the predator Utahraptor.

Iguanacolossus fortis (“mighty colossal Iguana”) (above) was found at a site near the town of Green River. It is ~30ft long and is probably a few million years older than Hippodraco.

Click to enlarge

Reduced consensus tree of 11,850 MPTs of 358 steps each, following ordering of 22 multistate characters. Numbers below and to the left of some nodes correspond to the following clade names: 1, Ornithopoda; 2, Iguanodontia; 3, Rhabdodontidae; 4, Dryomorpha; 5, Dryosauridae; 6, Ankylopollexia; 7, Styracosterna; 8, Hadrosauriformes; 9, Hadrosauroidea.