New Species of Horned Dinosaur From Triceratops Family Discovered in Arizona

Paleontologists have discovered a new species of horned dinosaur in southeastern Arizona that is closely related to the iconic Triceratops.

A team from the New Mexico Museum of Natural History and Science (NMMNH), led by Sebastian Dalman, assessed two specimens discovered around 20 years ago in the Fort Crittenden geological formation. They found that the bones belonged to a previously undescribed animal in the dinosaur family Ceratopsidae—of which Triceratops is a member.

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Ceratopsids were quadrupedal dinosaurs that had characteristic beaks, rows of shearing teeth in the back of the jaw, elaborate nasal horns and a frill at the back of the head.

According to a paper published in the NMMNH's latest bulletin, the two specimens—which are represented by incomplete skull bones—were found in shale deposits dated to the late Campanian period, suggesting they lived around 73 million years ago.

The researchers estimate that the new species—which has been named Crittendenceratops krzyzanowskii in reference to Stan Krzyzanowski, who found the fossils—was about 11-feet long and weighed roughly 1,500 pounds.

"In 2015, while at the New Mexico Museum of Natural History in Albuquerque, I began my research on ceratopsian dinosaurs and came across what is now called Crittendenceratops krzyzanowskii in the collection of the material," Dalman told Newsweek.

"I told my boss and co-author Spencer Lucas that this is a new species and that I am going to work on it. I am a taxonomist and morphologist, so I was able to find numerous morphological features right away in the material of Crittendenceratops to establish a new species.

"Later with the help of my good friend and co-author of other projects, Jonathan Wagner, a new phylogenetic analysis was conducted that shows the relationships of Crittendenceratops to other ceratopsians."

Ceratopsids are divided into two subfamilies: Chasmosaurinae, which are generally characterized by long, triangular frills and well-developed brow horns, and Centrosaurinae—which had well-developed nasal horns, shorter and more rectangular frills and elaborate spines on the back of the frill. C. krzyzanowskii falls into the latter subgroup.

These horns and frills exhibit remarkable variation and are the principal means by which the various species have been recognized, although researchers are still not entirely clear about what their purposes are. Some have speculated that they were used to defend against predators. However, others have suggested that they were used in mating displays instead.

Centrosaurinae are then further divied into three smaller groups, known as "tribes," one of which is the recently identified Nasutoceratopsini. According to Dalman, C. krzyzanowskii is the newest member of this tribe.

"The new species has a characteristic frill previously unknown among other nasutoceratopsins," Dalman said. "The significance of this discovery is that Crittendenceratops represents the youngest member of Nasutoceratopsini and that this group was still living in North America near the end of the Cretaceous.

"It coexisted with two other groups of horned dinosaurs (ceratopsians): centrosaurs and chasmosaurs. It also shows that ceratopsian dinosaurs were highly diverse both morphological and taxonomical."

The authors wrote: "Between the mid-1990s and 2000, a number of new ceratopsian specimens were collected by teams at the Arizona-Sonora Desert Museum and the New Mexico Museum of Natural History and Science from the upper Campanian Fort Crittenden Formation of Adobe Canyon within the Santa Rita Mountains of southeastern Arizona. These new specimens provide important new information about the morphologic and taxonomic diversity of Ceratopsidae in North America."

It's possible that C. krzyzanowskii will be displayed at the NMMNH in the future, KRQE Media reported.

This article has been updated to include additional comments from Sebastian Dalman.

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An artist's illustration of Crittendenceratops krzyzanowskii. Sergey Krasovskiy