The newly-described dinosaur species lived in what is now the United States between 100 and 94 million years ago (Cretaceous period). The ancient creature was approximately 1.8 m (5.9 feet) in length and 60 cm (2 feet) tall. Named Nevadadromeus schmitti, it ran on its two legs and had a beak at the front of its mouth.
The animal had features of both Thescelosaurinae and Orodrominae dinosaur subfamilies, but the paleontologists think it more likely to be a thescelosaurine dinosaur. “Due to the very fragmentary nature of the specimen, phylogenetic analysis yields statistically insignificant results,” said Dr. Joshua Bonde, director of the Nevada Science Center, and his colleagues. “Nevertheless, a few taxonomically important characters, particularly those of the femur, support the hypothesis that this is a thescelosaurine, and a new genus and species.” “This would represent the earliest occurrence of thescelosaurines in the fossil record of North America as all other thescelosaurines from the continent date to the Maastrichtian age of the Late Cretaceous epoch.”
The partial fossilized remains of Nevadadromeus schmitti were recovered from the layers of the Willow Tank Formation at Valley of Fire in southern Nevada. “Bones identified include the proximal femora, a series of vertebrae missing neural arches, several pedal phalanges, fragments of ossified tendons, and some as yet unidentified elements,” the paleontologists said. “The geographic position of the Willow Tank Formation depocenter, very proximal to the Sevier highlands of the time, likely experienced some biogeographic insularity from other areas represented by contemporaneous units of western North America, e.g., Mussentuchit Member of the Cedar Mountain Formation of Utah, the Wayan Formation of Idaho, and the Blackleaf Formation of Montana.”
The discovery of Nevadadromeus schmitti is reported in a paper in the Journal of the Arizona-Nevada Academy of Science.
Joshua W. Bonde et al. 2022. Nevadadromeus schmitti (gen. et sp. nov.), a New Basal Neornithischian with Affinities to the Thescelosaurinae, from the Upper Cretaceous (Cenomanian) Willow Tank Formation of Southern Nevada. Journal of the Arizona-Nevada Academy of Science 50 (1): 1-8; doi: 10.2181/036.050.0101
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