By Will Dunham
WASHINGTON (Reuters) – About 78 million years ago, on what was then a subtropical coastal plain – today the badlands of northern Montana – there lived a four-legged herbivorous dinosaur, built somewhat like a rhinoceros, with a set of fabulously ornate horns. head.
This newly identified dinosaur, called Lokiceratops rangiformis, was about 6.7 meters long, weighed about 5.5 tons and used a powerful beak at the front of its mouth to graze low-growing vegetation such as ferns and flowers. plants, scientists said Thursday.
Lokiceratops had two curved horns over 40 cm long above its eyes, small horns on its cheeks, and blades and spikes along the extended shield of its head. On this frill, he had at least 20 horns, including an asymmetrical pair of curved, blade-like horns, each about 61 cm long. These are the largest horns ever seen on a dinosaur.
These blade-like horns, evocative of the weaponry wielded by the trickster god Loki in Norse mythology, helped inspire its scientific name, which also recognizes the fossils’ permanent home at the Museum of Evolution in Denmark. The name means “horned face of Loki” and “shaped like a caribou,” referring to the fact that its frill displays horns of different lengths on each side, like caribou antlers.
It was one of numerous species of horned dinosaurs, called ceratopsians, that roamed western North America during the Cretaceous period, at a time when a large inland sea divided the continent in half.
Lokiceratops goes beyond bizarre helmets to ceratopsians, according to paleontologist Joe Sertich of the Smithsonian Tropical Research Institute and Colorado State University, co-lead author of the study published in the journal PeerJ.
“The horns and frills were likely used for display in Lokiceratops and other horned dinosaurs. These displays could have been used to intimidate rivals, attract mates, or recognize conspecifics,” Sertich said.
The lack of a nasal horn, present in many ceratopsians, makes it less likely that Lokiceratops used its horns to defend itself against predators, according to paleontologist and study co-lead author Mark Loewen of the University of Utah and the Museum. of Utah Natural History.
Lokiceratops fossils were discovered in Montana, about 2 miles south of the U.S.-Canada border. Lokiceratops inhabited a coastal plain of forests, lakes, and swamps along the eastern coast of Laramidia, the landmass that comprised western North America.
The family tree of ceratopsians has two main groups: chasmosaurines, including the largest of the horned dinosaurs Torosaurus and Triceratops, and centroaurines, such as Lokiceratops.
Dinosaurs from these two groups may have fed differently, minimizing their competition for resources. Ceratopsian dinosaurs had mouths containing more than 200 teeth that could cut through vegetation.
Surprisingly, Lokiceratops was one of five species of horned dinosaurs that shared the same ecosystem. Four of them were centroaurines, including two close relatives of Lokiceratops in Medusaceratops and Albertaceratops.
“In effect, this is like finding five species of elephant living in the same savannah in Kenya,” said Loewen.
The presence of all these animals together indicates that there was a rapid evolution of new centroaurine species occurring in a limited geographic region, Sertich said.
Other dinosaurs in this ecosystem included the herbivorous duck-billed dinosaur Probrachylophosaurus and a large carnivorous dinosaur, known only from tooth fossils and as yet unnamed, from the same lineage as the later T. rex. Lokiceratops was the most massive herbivore in the ecosystem.
“This is the first time that five ceratopsians have been recognized in the same ecosystem. For more than a century, it was believed that no more than two could coexist in the same ecosystem, but emerging evidence here in Montana and elsewhere in southern Laramidia , is revealing unexpected richness,” said Sertich.
“This parallels a pattern observed in mammal evolution that is still on display in East and South Africa with bovids – antelopes and buffaloes,” Sertich added.
(Reporting by Will Dunham, Editing by Rosalba O’Brien)
