Researchers have discovered fossilized teeth of a small rodent-like creature called Sikuomys mikros, nicknamed the “glacial rat,” which lived over 70 million years ago in what is now Alaska. This mouse-sized creature thrived in freezing temperatures and the darkness of the Arctic winter, along with various dinosaur species.

The teeth, measuring only 1 to 1.5 millimeters in size, were found in sediment collected from three different sites in the Prince Creek Formation, an area rich in dinosaur fossils. The teeth were distinct enough from those of their close relatives to classify it as a new species.

Although little is known about the behaviors and lifestyle of this creature, scientists speculate that it likely remained active throughout the winter, feeding on insects and other invertebrates to survive in the harsh environment. It is believed that the small size of Sikuomys mikros is an evolutionary adaptation that allowed it to require less food during the winter months.

The Prince Creek Formation, located above the Arctic Circle, provides a unique window into the prehistoric inhabitants of the region during the dinosaur era. The discovery of the teeth of the “glacial rat” contributes to our understanding of the diverse ecosystems that existed in the ancient Arctic, challenging our conceptions of the limitations of life in extreme environments.

Source: Journal of Systematic Palaeontology (August 2021)