Randall Irmis, curator of paleontology at the Natural History Museum of Utah and an assistant professor at the University of Utah, is investigating the rise of dinosaurs in southeastern Utah.
Two hundred million years ago the ancient life we are hoping to discover in the rocks of southeastern Utah did not reside in the high arid desert climate found in the Colorado Plateau of today. Rather, the Triassic American Southwest was crisscrossed by rivers, streams and floodplains similar in size to today?s Mississippi River and its tributaries.
The rocks in which we are searching, called the Chinle Formation, comprise the sediments laid down by this ancient river system.
The formation?s multicolored candy-striped beds are famous not only for their early dinosaur fossils, but also because they preserve large logs of colorful petrified wood, remains of giant conifer trees that dotted the landscape 220 to 210 million years ago.
These remains are best preserved in places like the Painted Desert of Petrified Forest National Park in northeastern Arizona. The fossil trees, other leaf remains and the sediments themselves help paleontologists understand what the environment was like millions of years ago, and how it has changed through time.
The plants, trees and animals from these ancient ecosystems are well known for Arizona and New Mexico, but poorly understood from rocks in Utah. One of the major questions our team hopes to answer is whether the environment, plants and animals in southern Utah might have been different from those preserved in the Chinle Formation rocks farther south.
We have reason to think this might be the case. During the Triassic Period, most of the continents we know today were assembled together in a single supercontinent called Pangaea. An ambitious early dinosaur could have conceivably walked from Argentina to Canada if it had the time.
Within this giant continent, what is now North America was much closer to the Equator; specifically, the American Southwest was in the tropics, between 5 and 15 degrees north latitude, rather than in its present position of 30 to 40 degrees north. This had distinct effects on climate, which affected the organisms in these ancient ecosystems.
Based on detailed new information from rocks of similar age of eastern North America, we know that the Triassic climate at the Equator was hot and humid, but as you traveled north of 5 degrees, conditions became progressively warmer and drier, with a more seasonal climate.
This greatly affected the animals living in these ecosystems, with different types of herbivores living at different latitudes, despite the fact that there were no great physical barriers to prevent them from mixing.
Our team is hoping to discover whether the Chinle Formation of southern Utah was drier and more seasonal than that of Arizona, and if so, how that affected the types of plants and animals living there. The only way to find this out is to put our eyes and feet to the rocks, and look for clues to the ancient life and climate of Utah 210 million years ago.
This research is supported by a grant from the National Geographic Society?s Committee for Research and Exploration, and is conducted with research permits from the Bureau of Land Management.
Source: http://scientistatwork.blogs.nytimes.com/2012/08/24/traveling-to-tropical-utah/?partner=rss&emc=rss
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