Ancient 'Ice Mouse' Provides Chilling Insights Into Prehistoric Alaska

Researchers discovered a tiny creature, about the size of two nickels, that lived in Alaska's cold 70 million years ago.

According to research published in the Journal of Systematic Palaeontology in August, the small species known as Sikuomys mikros, or "ice mouse," managed the harsh cold in the middle of a landscape populated by powerful dinosaurs.

Smaller Than Present Mouse

During the ice mouse's existence, the Prince Creek Formation (PCF) was located above the Arctic Circle and endured four months of continuous darkness every year. The rodent appears to have adapted successfully to its challenging environment despite snowfall and cold temperatures.

The ice mouse was found by University of Colorado, Boulder geological sciences professor Jaelyn Eberle. The animal's small, 1 to 1.5-millimeter teeth helped Eberle and her colleagues identify it.

"It is kind of interesting to imagine all these great big dinosaurs marching around alongside the shrew-like animal," Eberle said, as quoted by Insider. These individuals are diminutive because they are smaller than the average house mouse.

Resilient Small Creature

In contrast to its hibernating cousins, this little animal lived year-round despite resembling modern-day shrews. During the severe Alaskan winters, it probably survived on a diet of worms and insects by burrowing underground or behind leaf litter. Researchers believe this underground existence helped the ice mouse survive the meteorite hit that wiped off dinosaurs 66 million years ago, according to the Sacramento Bee.

This finding offers a rare look into the prehistoric environment of Alaska, shedding light on a time when arctic forests coexisted with dinosaurs, tiny animals, and birds, per YNet News. The sole traces of these ancient animals are a few teeth and jaw pieces, unlike modern dinosaurs, who have left behind significant bones.

The ice mouse is an intriguing exception to the widespread norm in mammals that species tend to grow bigger at higher latitudes and colder climes. This ancient species' size decreased, possibly due to a shortage of food during the severe Alaskan winters.

The creature spent the winter underground, which may have helped it survive the severe Alaskan temperature following the meteorite event, according to Eberle's research.