Newswise — A Boise State University study has shed new light on how a shallow seaway that once extended across the central part of North America circulated during one of earth’s warmest periods, about 82 to 87 million years ago. The findings could help explain why animals differ in the North and South regions.
Called the Interior Seaway, it stretched from the Gulf of Mexico to the Arctic. Scientists have thought for years that the water circulation was one long cell, with water moving in a large counter-clockwise circulation. But now, thanks to research by Boise State geoscientists, that collective thought has been put into question. The study found that the water circulation actually was separated into two cells: one southern circulation, stretching from the Gulf to modern-day Kansas, and a northern circulation, from Kansas to the Arctic.
The results appear online in the journal Nature Geoscience.
“This study unequivocally proves that the southern fauna lived in warmer and saltier water, which led to different animals in that area from the north,” said study coauthor Matthew Kohn, professor of geosciences at Boise State. “The difference in temperature between the two circulations was about seven degrees Fahrenheit, which is a major difference between the two circulations and a major difference for animals.”
Boise State researchers measured the ratio of different masses of oxygen atoms in nearly 100 turtle bones and fish teeth. They found large differences in temperature and salt content between the Gulf of Mexico and Kansas. The researchers said these differences indicate that circulation must have been separated into southern and northern circulation cells, rather than having one long cell stretching from the Gulf to the Arctic.
The researchers said the differences explain why marine animals are so different in the North versus the South.
“This issue is important for understanding climate fundamentals,” Kohn said. “If we can understand how mass, heat and water moved in Earth’s other climate states, especially the warm ones, we might be able to make predictions about future climatic warming and cooling periods.”
The project was funded by the American Chemical Society and the National Science Foundation.
Learn More About Research at Boise State UniversityAn emerging metropolitan research university of distinction, Boise State University has launched a new website – beyondtheblue.boisestate.edu – to showcase the research expertise and innovative spirit that exists in many fields at the university. Known for its unique blue turf and nationally ranked football program, Boise State is demonstrating its creativity beyond the blue in an ongoing series of faculty podcasts where faculty experts provide insight into today’s issues, challenges and topics of interest.
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