Earth Protect Blog

By Olivia Doak

Daily Camera

Paleontologists, led by a University of Colorado Boulder professor, discovered a new tiny mammal in northern Alaska that lived in extremely cold temperatures during the age of the dinosaurs.

The tiny fossil mammal lived about 73 million years ago and is guessed to have weighed about 11 grams, which is the equivalent of an empty aluminum can or a couple of nickels.

Jaelyn Eberle is a CU professor, the interim director of the CU Boulder Museum of Natural History and curator of vertebrate paleontology. Eberle led a team of researchers from different universities to Alaska to collect sediment samples from a site with known fossils to analyze in a lab.

The sediment is then washed and sorted under a microscope, where the mammal’s tiny teeth — which are about a millimeter or millimeter and a half in length — were found.

“Up until this point, we really don’t know much about what was living up that far north, nor do we know how it was living up there,” Eberle said. “I would say this is one of the few studies that we can actually get at behavior simply by looking at the teeth, comparing sizes and estimating body masses.”

Paleontologists are able to learn considerable information about mammals just by looking at its teeth. Teeth can identify a species, Eberle said, which is how they knew they found a new mammal. There’s also a relationship to teeth size and body size, which is how the approximate size of the mammal was estimated.

By comparing it to its distant relatives, Eberle said this mammal probably looked like a shrew with a little body and long snout. It also may have had some shared behaviors, including a strong sense of smell, could burrow underground and likely did not hibernate. The mammal also probably fed on insects, larvae and worms based on the sharpness of its teeth, she said.

These tiny fossil teeth are giving researchers a new perspective on ancient Alaska, said study co-author Patrick Druckenmiller, director of the University of Alaska Museum of the North.

“Seventy-three million years ago, northern Alaska was home to an ecosystem unlike any on Earth today,” Druckenmiller said in a news release. “It was a polar forest teeming with dinosaurs, small mammals and birds. These animals were adapted to exist in a highly seasonal climate that included freezing winter conditions, likely snow and up to four months of complete winter darkness.”