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Dinosaur evolution, migration linked to the rise of the Rocky Mountains


Remains of horned dinosaurs, like the Triceratops, have been found in North America (photo from the Houston Museum of Natural Science)
Remains of horned dinosaurs, like the Triceratops, have been found in North America (photo from the Houston Museum of Natural Science)

Cheryl Santa Maria, staff writer

August 6, 2012 — A study published by researchers at Ohio University has linked the development of the Rocky Mountains and a seaway to dinosaur evolution and migratory patterns.

Edmontosaurus live in North America 73 million years ago (photo from the Houston Museum of Natural Science)
Edmontosaurus live in North America 73 million years ago (photo from the Houston Museum of Natural Science)

Duck-billed and horned dinosaurs were once plentiful in North America, peaking about 75 million years ago.

But roughly 10 million years after that, numbers dwindled.

It's a discrepancy that, according to lead researcher Terry Gates, has never been adequately explained.

Scientists pieced the pre-historic puzzle together by tracking the geology of North America. They found that the evolution of the land had a profound impact on dinosaur breeding and migration patterns.

The changes were set in motion in the early-to-mid Cretaceous period, when the Sevier Mountains were created.

This massive mountain range extended from the American Southwest to Alberta and created a seaway that divided North America into three large islands -- all of which were heavily populated by dinosaurs.

The development of the Rocky Mountains had a profound impact on dinosaur evolution (courtesy: Devon T.)
The development of the Rocky Mountains had a profound impact on dinosaur evolution (courtesy: Devon T.)

A tectonic shift would then create the Laramide Orogeny off to the east -- setting the stage for the development of the Rocky Mountains.

"At that time, it appears that geographic, as well as probably ... ecological, barriers created by the rise of mountain ranges and the seaway caused isolation of the northern and southern populations of the crested duck-billed and horned plant-eating dinosaurs," explained study contributor Albert Prieto-Márquez in a statement.

"We hypothesize that such isolation facilitated rapid speciation and increased diversity in these animals."

For a short while, the two mountain ranges and the seaway created a surge in the dinosaur population, with duck-billed and horned species being born at an "explosive" rate.

But the continued rise of the Rocky Mountains put an end to that.

As the Rockies elevated further, dinosaurs were provided with more space to roam -- slowing down the rate of evolution.

The study, which was published last week in the journal PLoS ONE, has shed new light on how dinosaurs evolved in a constantly-changing environment.

The findings also demonstrate how environmental changes could have allowed North American dinosaurs to migrate into South America and Asia.

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