Scientists discover tiny ‘ice rat’ dinosaur fossil

Fossil teeth of a small shrew-like mammal that lived about 73 million years ago, during one of the coldest periods on Earth, have been found by paleontologists in northern Alaska.

A group of researchers, led by Dr. Jaelyn Eberle of the University of Colorado Boulder, described the creature from the Late Cretaceous period in a study published in the Journal of Systematic Palaeontology. They named it Sikuomys mikros, a portmanteau of “Siku,” an Iñupiaq (Inuit language spoken in northern Alaska) word for ice, and “mys” and “mikros,” the Greek words for mouse and little, respectively. .

In fact, the “little ice mouse” wasn’t a mouse at all but belonged to an extinct family of mammals called Gypsonictops. However, it was really small. This furry creature was probably the size of a modern chick, weighing 11 grams. It lived in northern Alaska, which at the time was much farther north than it is today.

In that region, this small animal would experience darkness for four months during the winter months and the temperatures would drop dramatically. “S. the mikros never slept, but they were active all year round, just like the shrews that already exist,” says Dr. Eberle.

Dr. Eberle and his colleagues identified an ancient mammal based on a few tiny teeth, each about the size of a grain of sand. These rare fossils have opened a new window into ancient Alaska for researchers.

“Seventy-three million years ago, northern Alaska was home to an ecosystem unlike the one on Earth today,” he said. “It was a jungle filled with dinosaurs, small mammals and birds. “These animals have adapted to a very cold winter season, possibly snow and four months of total winter darkness,” said Patrick Druckenmiller, director of the University of Alaska Museum of Northern Fairbanks. .

Researchers, including paleontologists from Florida State University, unearthed fossils in sediments along the Colville River—not far from the Beaufort Sea on Alaska’s north coast.

“Our team’s research reveals the ‘lost world’ of organized Arctic animals,” said Gregory Erickson, author and researcher at Florida State University. “Prince Creek serves as a natural experiment for these animals and their behavior in the face of extreme seasonal climate change.”

Unlike themodern dinosaurs, which left behind large skeletons, the only bones left of the mammals of this region are a few teeth and fragments of jaws. To examine these precious samples, the researchers collected soil from the river bank, brought the samples to the lab, and washed away the mud. Finally they sorted and examined the samples under a microscope.