2 brand-new transitional types of plant-eating horned dinosaurs have actually been uncovered in New Mexico, the United States.
Navajoceratops sullivani and Terminocavus sealeyi. Image credit: Ville Sinkkonen & Denver Fowler.
The newly-discovered dinosaurs wandered the Earth around 75 million years earlier (Cretaceous duration).
Called Navajoceratops sullivani and Terminocavus sealeyi, both types come from Ceratopsidae, the exact same household as well-known horned dinosaurs Triceratops, Centrosaurus, and Styracosaurus.
Their fragmentary skulls were discovered from the Hunter Wash Member of the Kirtland Development in New Mexico.
The specimens are intermediate in age in between 2 formerly understood ceratopsid dinosaurs Pentaceratops and Anchiceratops.
Pentaceratops lived 75.3 million years earlier in New Mexico and had a distinct deep notch on the back border of the frill, and a set of spikes at the center of the frill that turn outwards like the wings of a butterfly.
Anchiceratops had no notch in its frill and lived 3.8 million years later on in what is now Canada.
In the 1990s, Texas Tech University paleontologist Thomas Lehman proposed that Pentaceratops may have been the forefather of Anchiceratops.
Navajoceratops sullivani and Terminocavus sealeyi are intermediate fit in between these 2 dinosaurs and demonstrate how the notch in the frill ended up being even much deeper through time and ultimately surrounded itself, describing the absence of a notch in Anchiceratops.
“The 2 intermediate skulls form crucial links in a 5 million year family tree extending from Utahceratops through Pentaceratops, to Anchiceratops,” stated research study authors Dr. Denver Fowler and Dr. Elizabeth Freedman Fowler from Badlands Dinosaur Museum and Museum of the Rockies.
The parietal frills of Navajoceratops sullivani (top) and Terminocavus sealeyi (bottom). Image credit: Fowler & Freedman Fowler, doi: 10.7717/peerj.9251.
The brand-new specimens exposed a splitting occasion deep in the evolutionary history of long-frilled ceratopsids (chasmosaurines), after which a Pentaceratops family tree developed a gradually deepening notch in the frill, contrasting versus its sis group, the Chasmosaurus family tree, which developed a gradually shallower notch.
“The origin of this evolutionary split took place throughout the Late Cretaceous duration, when a huge interior seaway flooded the lowlands of The United States and Canada dividing it into eastern and western subcontinents,” the paleontologists stated.
“A brief duration of specifically high water level 85-83 million years ago brought the edge of the sea really near to the young Rocky Mountains.”
“For numerous miles throughout what is now main Utah to southern Alberta, the seaside plain would have been just 5-10 km large, offering really little environment for dinosaurs.”
“This would have efficiently cut off northern and southern populations, which then most likely developed in seclusion into 2 unique family trees. Nevertheless, after 83 million years earlier, the sea declined from the mountain front, enabling northern and southern populations to blend once again.”
The group’s paper appears in the journal PeerJ.
D.W. Fowler & E.A. Freedman Fowler. 2020. Transitional evolutionary types in chasmosaurine ceratopsid dinosaurs: proof from the Campanian of New Mexico. PeerJ 8: e9251; doi: 10.7717/peerj.9251
This short article is based upon text supplied by Dickinson Museum Center.