A team of paleontologists, including lead author and 2008 UNL graduate Andrew McDonald, has named a new species of dinosaur based on an incomplete skeleton found in western New Mexico on land administered by the U.S. Bureau of Land Management.
The new species, dubbed Jeyawati rugoculus, comes from rocks that preserve a swampy forest ecosystem that thrived near the shore of a vast inland sea 91 million years ago. Jeyawati is a member of a remarkable assemblage of dinosaurs and other animals that was totally unknown 15 years ago and that was featured in the 2001 Discovery Channel documentary, “When Dinosaurs Roamed America.”
Dinosaurs that coexisted with Jeyawati include Zuniceratops, the earliest known North American horned dinosaur, and Nothronychus, a strange herbivorous beast belonging to a lineage that, until the discovery of Nothronychus, was known only from Asia. Jeyawati adds another fascinating character to the story of North America’s dinosaurs.
The first part of the name Jeyawati rugoculus is pronounced “HEY-a-WHAT-ee,” essentially meaning “grinding mouth,” and is derived from two words in the language of the Zuni people, who have long inhabited western New Mexico. The meaning of the name Jeyawati is a reference to the sophisticated chewing mechanism evolved by the herbivorous lineage to which Jeyawati belongs. The second part of the name, rugoculus, comes from the Latin words ruga and oculus and means “wrinkle eye,” describing a unique feature of the new species. One of the bones that forms the eye socket exhibits a peculiar rough or wrinkly texture on its outer side; in other dinosaurs, such a texture on skull bones has been suggested to have supported enlarged scales on the top of the skull. Thus, Jeyawati rugoculus might have sported one or more large scales above and behind its eye, giving it a strangely striking appearance.
Jeyawati evidently endured a hard life. Among the many bits of ribs found with the skull bones, several large pieces have a swollen, rough surface, indicating that the animal suffered broken ribs through some misfortune and that those injuries had healed by the time the animal died.
The partial skull and other fragments of Jeyawati were discovered in 1996 by paleontologist Douglas Wolfe, principal investigator of the Zuni Basin Paleontological Project, his wife Hazel, and their son Christopher. Subsequent excavation and collection was carried out with the permission of the BLM over the following 13 years with the aid of James Kirkland (State Paleontologist with the Utah Geological Survey), volunteers from the Southwest Paleontological Society, and many other volunteers from around the country. The fragile fossils were carefully freed from the remaining rock by preparators Harold and Phyllis Bolan and are stored at the Arizona Museum of Natural History in Mesa.
In 2006, McDonald, then an undergraduate geology student at UNL under the supervision of professor David Loope, began a project to describe the fossil in UNL’s Undergraduate Creative Activities and Research Experiences program. McDonald and Wolfe first met when McDonald was a student at Sacred Heart-Griffin High School in Springfield, Ill., and when it came time for him to look for a UCARE research project, he received permission from Wolfe to work on the specimen.
McDonald’s analysis revealed that the bones were sufficiently distinct from those of other dinosaurs to warrant the naming of a new species. It also became clear that Jeyawati is a close relative of the duck-billed hadrosaurs, which were immensely abundant across the Northern Hemisphere for much of the Late Cretaceous Epoch, between 80 million and 65 million years ago. However, Jeyawati retains some primitive features of the teeth and jaws that preclude it from being a fully-fledged hadrosaur. McDonald, a Ph.D. student since 2008 at the University of Pennsylvania, where he works with paleontologist Peter Dodson, has a more extensive project under way to determine the evolutionary relationships of Jeyawati and many of its relatives.
“Andrew is unusually focused and unusually hard-working,” Loope said. “He has been interested in dinosaurs since an early age and has steadily built his knowledge since age 10. He got started on this New Mexico dinosaur while still at UNL and has carried through with it to completion like I knew he would.”
McDonald, Wolfe, and Kirkland published their findings in the May issue of the Journal of Vertebrate Paleontology.
- By Andrew McDonald and Tom Simons