100 million-year-old skull of oldest horned dinosaur in North America found
Fossil from tiny plant eater, Aquilops americanus, suggests horned dinosaurs originated in Asia
The oldest horned dinosaur in North America sported a hooked beak, pointy cheeks, and was no bigger than a crow, according to research on its ancient remains.
The skull of the prehistoric creature that stalked the land more than 100m years ago was recovered by fossil hunters from rock in Carbon County, Montana. The skull, discovered by Scott Madsen of the Utah Geological Survey, which investigates and reports on Utah’s geologic hazards, measured only 8.4cm long and dates to about 106m years old.
Named Aquilops americanus, the diminutive beast resembles similar dinosaurs that lived in Asia at the time and migrated from there to North America around 110m years ago, according to a report in the journal, Plos One .
“This was a small plant eater and we know from its hooked beak that it was pretty selective, nipping bits off whatever vegetation was around,” said Andrew Farke at the Raymond M Alf Museum of Paleontology in Claremont, California.
The creature probably hid among the bushes in its habitat, where one of its main predators was deinonychus, a dinosaur closely related to the velociraptor, Farke added.
Before the latest discovery, the oldest known horned dinosaur from North America was zuniceratops, which lived about 90m years ago. Remains of that animal were dug up in Arizona. Other fossils have been found, but these are mostly fragments of teeth and scraps of bone that are insufficient to identify a species from.
“Aquilops lived nearly 20m years before the next oldest horned dinosaur named from North America,” said Farke. “Even so, we were surprised that it was more closely related to Asian animals than those from North America.” Another horned beast, the triceratops, emerged around 40m years after Aquilops.
According to Farke, the fossil evidence suggests that the horned dinosaurs originated in Asia and spread into North America later on, though he said more field studies were needed to be sure.
Having only the skull to go on, the researchers know nothing about the skin of the animal. Related dinosaurs were scaly, though some had quills, or hair-like structures, on their skin.
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