“I will be in southern Utah for three or four weeks beginning in mid-June,” he says. “I am interested in mammalian evolution during the Jurassic and Cretaceous time periods, when the ancestors of modern mammals (marsupials and placentals) split from ancient lineages.”
The Jurassic period, known as the “Age of Reptiles” lasted for 64 million years, from about 208 to 144 million years ago. During this period, what is now North America had not yet separated from land masses in Europe and Africa.
The Cretaceous period lasted from the end of the Jurassic period to about 65 million years ago. This period saw the separation of the continents.
“This time interval is poorly known in North America, and events on this continent might hold the key to understanding emerging patterns from the global distribution of early mammals,” Dr. Davis said.
At this time, much of North America was covered by an internal sea.
“ Conventional wisdom holds that modern mammals evolved on northern landmasses (most likely in Asia) at the beginning of the Cretaceous, but new fossils raise the possibility that the root of our family tree might extend back much further in time, and maybe even to the southern half of the globe. The rocks in Utah best record this interval on our continent, but they have yet to yield fossils,” he says.
By the end of the Cretaceous period, about 75 percent of all species, including marine, freshwater, and terrestrial organisms, became extinct. The rather abrupt disappearance of Cretaceous life remains a mystery.
Dr. Davis received his bachelor’s degree from the College of William and Mary and his master’s and doctoral degrees from the University of Oklahoma. His research training is in paleontology. He studies the evolutionary history of mammals, focusing on what was happening in the Age of Dinosaurs.
He did preliminary reconnaissance in this area of southern Utah last summer (Grand Staircase-Escalante National Monument), and identified some promising rock layers to explore more thoroughly.
“I have been looking for fossils in the field nearly every summer for the last 14 years, in Montana, Wyoming, South Dakota, Utah, and Texas. All were focused on looking for early mammals and occasionally dinosaurs, and our groups ranged from four experienced researchers to groups including a dozen high school students and affiliated educators.”
Dr. Davis says his goal is to investigate a period that has presented a challenge to paleontologists.
“The slice of time I am working in for this project represents a gap in the North American fossil record. We know quite a bit about life about ten million years later (the day of dinosaurs), and a little bit about life ten million years prior, but the evolutionary history of mammals and other small vertebrates (such as lizards) appears to be in flux during the time I am interested in (the Middle Jurassic Period). “
“Our knowledge of this interval comes from other parts of the world, but we have no clue what was happening in our own neighborhood,” he states.
“I have no doubt that new species lie hidden in those rocks in Utah.”
What did the Joplin area look like in a previous epoch? Dr. Davis it was significantly different, even millions of years after the time period he will be studying.
“Ten million years ago, the poles of the globe were largely free of ice, so sea levels were much higher and Joplin would be a wetter, warmer place than it is now,” he states. “Primitive horses, camels, and elephants would have roamed the grasslands, stalked by saber-toothed cats. A wild place!”