Washington, Dec 11 (IANS): By analysing a dinosaur skull discovered in Montana, US, researchers have determined that the oldest horned dinosaur in North America, which lived around 100 million years ago, is closely related to similar species in Asia. 

The findings support a late Early Cretaceous (approximately 113-105 million years ago) intercontinental migratory event between Asia and North America.

The scientists have named the dinosaur Aquilops americanus which exhibits definitive features of neoceratopsian -or horned dinosaurs - from the Early Cretaceous in North America.

"Aquilops lived nearly 20 million years before the next oldest horned dinosaur named from North America," said Andrew Farke from Raymond M. Alf Museum of Paleontology in California.

"Even so, we were surprised that it was more closely related to Asian animals than those from North America," he noted.

The skull of Aquilops is comparatively small, measuring 84 mm long and is distinguished by several features, including a strongly hooked rostral bone or beak-like structure and an elongated and sharply pointed cavity over the cheek region.

When alive, it was about the size of a crow.

The study appeared in the journal PLOS ONE.