A tubby dinosaur sporting horns each the length of a baseball
bat roamed what is now Mexico some 72 million years ago.


Remains of the plant-eating dinosaur, now called Coahuilaceratops magnacuerna, were
unearthed from the Cerro del Pueblo Formation in Coahuila, Mexico. Fossils
belonging to both an adult and juvenile of the species were unearthed at the
site.


When alive, the dinosaur would have been about the size of a
rhinoceros, weighing 4 to 5 tons (3,600 to 4,500 kilograms), with horns
estimated to be 3 to 4 feet long (about 1 meter). The horns are considered the
longest of any ceratopsids, a group of plant-eating horned dinosaurs whose
members include the famous
Triceratops.


Like other horned dinosaurs, Coahuilaceratops probably used its headgear to attract mates and
fight with rivals of the same species.


“Being one of the largest herbivores in its ecosystem,
adult Coahuilaceratops probably didn’t have to worry about large tyrannosaur
predators,” said researcher Andrew Farke of the Raymond M. Alf Museum in
Claremont, Calif.


The new species, announced today, will be detailed in the book
“New Perspectives on Horned Dinosaurs” to be released next week by
Indiana University Press.


Monster storms


Mark Loewen, a paleontologist with the Utah Museum of
Natural History and lead author of the study, described the arid, desert
terrain where the dinosaur was recovered as nothing like Mexico during the Late
Cretaceous (97 million to 65 million years ago). At that time, due to high
global sea levels, the region was a humid estuary with lush vegetation, much
like the present-day Gulf Coast.


The high sea level created an interior seaway that split North
America into a western landmass called Laramidia and an eastern one called
Appalachia. Coahuilaceratops lived at the southernmost tip Laramidia.


Many dinosaur bones in the area are covered with fossilized
snails and marine clams, suggesting the dinosaurs lived adjacent to the
seashore.


Ancient ecosystem


In addition to Coahuilaceratops, the research team found
remains of two other
horned dinosaurs, two duck-bill dinosaurs, as well as the remains of
carnivores, including large tyrannosaurs (smaller, older relatives of T. rex) and more diminutive
Velociraptor-like predators armed with sickle-claws on their feet.


In fact, some of the sites in the area appear to represent mass death events, perhaps
associated with storms such as today’s hurricanes that occur in the region.


“Sitting near the southern tip of Laramidia, this
region may have been hammered by monstrous storms,” said study researcher Scott
Sampson, a paleontologistat the Utah Museum of Natural History. “If so,
such periodic cataclysms likely devastated miles of coastline, killing off
large numbers of dinosaurs.”


But that’s not how Coahuilaceratops died. “This was found with several individuals, but we don’t think a hurricane killed these guys,” Loewen told LiveScience. “Hurricanes came through and destroyed some of the dinosaurs. The actual one we’re announcing didn’t die that way.”


In all, the discoveries paint a picture of a diverse,
ancient ecosystem strewn with plant- and meat-eating dinosaurs, possibly
representing a previously unknown assemblage of species, the researchers say.


“Rather than focusing only on individual varieties of
dinosaurs, we are attempting to reveal what life was like in Mexico 72 million
years ago, and understand how the unique ecosystem of Mexico relates to
ecosystems to the north at the time,” Loewen said.


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