Paleontologists have examined a large assemblage of dinosaur tracks and fossilized plants from the Nanushuk Formation, which crops out over much of the central and western North Slope of Alaska, varying from 1,500 to 250 m (4,921 to 820 feet) thick from west to northeast.
“We’ve had projects for the last 20 years in Alaska trying to integrate sedimentology, dinosaur paleontology and the paleoclimate indicators,” said University of Alaska Fairbanks Professor Paul McCarthy.
“We’ve done work in three other formations — in Denali, on the North Slope and in Southwest Alaska — and they’re about 70 million years old.”
“This new one is in a formation that’s about 90 to 100 million years old.”
“What interested us about looking at rocks of this age is this is roughly the time that people think of as the beginning of the Bering Land Bridge — the connection between Asia and North America.”
“We want to know who was using it, how they were using it and what the conditions were like.”
“The mid-Cretaceous was the hottest point in the Cretaceous period.”
“The Nanushuk Formation gives us a snapshot of what a high-latitude ecosystem looks like on a warmer Earth.”
The Nanushuk Formation dates to roughly 94 million to 113 million years ago in the mid-Cretaceous period and about when the Bering Land Bridge began.
The fieldwork occurred between 2015 and 2017 and centered on Coke Basin, a circular geologic feature of the formation.
The basin is in the DeLong Mountains foothills along the Kukpowruk River, about 100 km (60 miles) south of Point Lay and 32 km (20 miles) inland from the Chukchi Sea.
In the area, the paleontologists found approximately 75 fossil tracks and other indicators attributed to dinosaurs living in a riverine or delta setting.
“This place was just crazy rich with dinosaur footprints. One site stands out,” said Dr. Anthony Fiorillo, a researcher at the New Mexico Museum of Natural History and Science.
“We were at a…
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