A newly described horned dinosaur that lived in New Mexico 82 million years ago is one of the earliest known species of ceratopsids, a group known as the horned or frill dinosaurs. The researchers reported their discovery in a publication of the journal PalZ (Paleontological Journal).
Menefeeceratops sealeyi adds important information to scientists’ understanding of the evolution of ceratopsid dinosaurs, which are characterized by horns and frills, as well as beaked faces. In particular, the discovery sheds light on the centrosaurine subfamily of horned dinosaurs, of which Menefeeceratops is believed to be the oldest member. Its remains provide a clearer picture of the group’s evolutionary path before its extinction at the end of the Cretaceous.
Steven Jasinski, who recently completed his doctorate. in the Department of Earth and Environmental Sciences of the Faculty of Arts and Sciences at Penn, and Peter Dodson of the Faculty of Veterinary Medicine and Penn Arts & Sciences, collaborated in this work, led by Sebastian Dalman of the New Mexico Museum of Natural History and Science. Spencer Lucas and Asher Lichtig of the New Mexico Museum of Natural History and Science in Albuquerque were also part of the research team.
“There has been a striking increase in our knowledge of the diversity of ceratopsids over the past two decades,” says Dodson, who specializes in the study of horned dinosaurs. “Much of these finds resulted from discoveries further north, from Utah to Alberta. It is particularly exciting that this find so far south is significantly older than any earlier find of ceratopsids. importance of the Menefee dinosaur fauna to understanding the evolution of Late Cretaceous dinosaur faunas throughout western North America. “
The fossil specimen of the new species, including several bones from an individual, was originally discovered in 1996 by Paul Sealey, a research associate at the New Mexico Museum of Natural History and Science, in the Cretaceous rocks of the Menefee Formation in northwestern New Mexico. A field team from the New Mexico Museum of Natural History and Science collected the specimen. Tom Williamson of the New Mexico Museum of Natural History and Science briefly described it the following year, and recent research on other ceratopsid dinosaurs and subsequent preparation of the specimen has shed important new light on the fossils. .
Based on the latest research, the researchers determined that the fossils represented a new species. The name of the genus Menefeeceratops refers to the rock formation in which it was discovered, the Menefee Formation, and to the group of which the species is a part, Ceratopsidae. The species name sealeyi honors Sealey, who unearthed the specimen.
Menefeeceratops is related but predates Triceratops, another ceratopsid dinosaur. However Menefeeceratops was a relatively small member of the group, reaching around 13 to 15 feet long, compared to Triceratops, which could grow up to 30 feet long.
Horned dinosaurs were generally large rhino-like herbivores that likely lived in groups or herds. They were important members of the Upper Cretaceous ecosystems in North America. “Ceratopsids are best known in various localities in western North America in the late Cretaceous towards the end of the dinosaur era,” says Jasinski. “But we have less information about the group, and their fossils are rarer, when you go back to them about 79 million years ago.”
Although the bones of the entire dinosaur were not recovered, a significant amount of the skeleton was preserved, including parts of the skull and lower jaws, forearm, hind limbs, pelvis, vertebrae and the ribs. These bones not only show that the animal is unique among known dinosaur species, but also provide additional clues about its life cycle. For example, fossils show evidence of a potential pathology, resulting from injury or minor illness, on at least one of the vertebrae near the base of its spine.
Some of the key features that set Menefeeceratops apart from other horned dinosaurs involve the bone that makes up the sides of the dinosaur’s steering wheel, known as the squamosal. Although less ornate than those of some other ceratopsids, Menefeeceratops’ squamosal has a distinct pattern of concave and convex portions.
Comparing the characteristics of Menefeeceratops with other known ceratopsid dinosaurs helped the research team trace its evolutionary relationships. Their analysis places Menefeeceratops sealeyi at the base of the evolutionary tree of the centrosaurine subfamily, suggesting that not only is Menefeeceratops one of the oldest known centrosaurine ceratopsids, but also one of the most evolutionarily basic.
Menefeeceratops was part of an ancient ecosystem with many other dinosaurs, including the recently recognized nodosaurid ankylosaur Invictarx and the tyrannosaurid Dynamoterror, as well as hadrosaurids and dromaeosaurids.
“Menefeeceratops was part of a thriving Cretaceous ecosystem in the southwestern United States with dinosaurs that predated many of the better-known members closer to the Late Cretaceous,” says Jasinski.
Although relatively less work has been done on collecting dinosaurs in the Menefee formation to date, researchers hope that more fieldwork and collection in these areas, as well as new analysis, will uncover more. Menefeeceratops fossils and ensure a better understanding of the ancient ecosystem. of which he was a part.
Peter Dodson is Professor of Anatomy in the School of Veterinary Medicine and Professor of Earth and Environmental Sciences in the School of Arts and Sciences at the University of Pennsylvania.
Steven E. Jasinski is Curator of Paleontology and Geology at the State Museum of Pennsylvania and Business Faculty at Harrisburg University of Science and Technology. He received his doctorate from the Department of Earth and Environmental Sciences at the School of Arts & Sciences at the University of Pennsylvania.
Sebastian G. Dalman is an associate researcher at the New Mexico Museum of Natural History and Science in Albuquerque.
Spencer G. Lucas is curator of paleontology at the New Mexico Museum of Natural History and Science in Albuquerque.
Asher J. Lichtig is an associate researcher at the New Mexico Museum of Natural History and Science in Albuquerque.
Jasinski was supported by Geo. L. Harrison and Benjamin Franklin scholarships while studying at the University of Pennsylvania. The research was also partially funded by a Walker Endowment Fellowship and a Paleontology Fellowship from the University of Pennsylvania.