Research led by scientists at the American Museum of Natural History shows that ammonitesan extinct type of shelled mollusk that's closely related to modern-day nautiluses and squidsmade homes in the unique environments surrounding methane seeps in the seaway that once covered America's Great Plains. The findings, published online on April 10 in the journal Geology, provide new insights into the mode of life and habitat of these ancient animals.
Geologic formations in parts of South Dakota, Wyoming, and Montana formed as sediments were deposited in the Western Interior Seawaya broad expanse of water that split North America into two land massesduring the Late Cretaceous, 80 to 65 million years ago. These formations are popular destinations for paleontologists looking for everything from fossilized dinosaur bones to ancient clam shells. In the last few years, groups of researchers have honed in on giant mounds of fossilized material in these areas where, many millions of years ago, methane-rich fluids migrated through the sediments onto the sea floor.
"We've found that these methane seeps are little oases on the sea floor, little self-perpetuating ecosystems," said Neil Landman, lead author of the Geology paper and a curator in the Division of Paleontology at the American Museum of Natural History. "Thousands of these seeps have been found in the Western Interior Seaway, most containing a very rich fauna of bivalves, sponges, corals, fish, crinoids, and, as we've recently documented, ammonites."
In the Black Hills region of South Dakota, Landman and researchers from Stony Brook University's School of Marine and Atmospheric Science, the Black Hills Museum of Natural History, Brooklyn College, the South Dakota School of Mines and Technology, and the University of South Florida are investigating a 74-million-year-old seep with extremely well-preserved fossils.
"Most seeps have eroded significantly over the last 70 million yea
|Contact: Kendra Snyder|
American Museum of Natural History