Shield ornamentation prompts researchers to name two new tribes of horned dinosaurs
Scientists have named two new clades, or tribes, of horned dinosaurs (ceratopsians) based on fossils collected from the United States and Alberta, Canada. The new tribes are Nasutoceratopsini and Centrosaurini. Research describing the updated relationships among horned dinosaurs appears online in the Canadian Journal of Earth Sciences.
|Nasutocerops showing the lack of frill-ornamentation typical of the newly named Nasutoceropsini tribe |
[Credit: Cleveland Museum of Natural History]
Nasutoceratopsini belongs to the subfamily Centrosaurinae, which includes dinosaurs with the most elaborate head shield ornamentation ever developed, such as the spikey Styracosaurus. In contrast, nasutoceratopsins are distinguished by having large, broad frills that lacked well-developed ornamentation. Unlike their flashy contemporaries, these dinosaurs weren't dinosaurian show-offs, choosing instead to blend into their environments.
|An illustration of Cornosaurus, a member of the newly named Centrosaurini tribe |
that has ornate frill displays [Credit: Cleveland Museum of Natural History]
"Nasutoceratopsins took a different evolutionary path from their centrosaurine cousins, which typically have highly ornamented skulls" said lead author Dr. Michael Ryan, Curator of Vertebrate Paleontology at the Cleveland Museum of Natural History. "We believe that the skull ornamentation was important for attracting mates. If nasutoceratopsins lacked boney ornamentation, it's possible that they may have used distinctive coloration patterns, social behaviors or vocalizations, like modern birds do in their courtship behaviors. But we'll never know for sure since those latter features don't fossilize."
|Pieces of the skull of CMN 88o4, a horned dinosaur collected in 1937 by C. M. Sternberg in southeastern |
Alberta, Canada, and recently assigned to the new horned dinosaur tribe Nasutoceratopsini
[Credit: Canadian Journal of Earth Sciences]
The fact that the two tribes are found together over a great distance in rocks of the same age indicates that they would have overlapped in the same regions at the same time.
|This illustration shows what CMN 88o4, the horned dinosaur specimen recently|
assigned to the new tribe Nasutoceratopsini, would have looked like
[Credit: Copyright: Andrew Atuchin]
The description of the two new horned dinosaur tribes is the latest in a series of new finds being made by Ryan and Dr. David Evans of the Royal Ontario Museum as part of their Southern Alberta Dinosaur Project, which is designed to fill in knowledge gaps about Late Cretaceous dinosaurs and study their evolution. This project focuses on the paleontology of some of oldest dinosaur-bearing rocks in Alberta and neighbouring rocks in northern Montana that are of the same age.
Source: Cleveland Museum of Natural History [December 13, 2016]