Alaska: Mini-Beutler lived between dinosaurs

69 million year old fossil is the northernmost known marsupial relic ever

The site of the tiny prehistoric marsupial is the Colville River in Alaska - so far north you have never discovered a marsupial. © Patrick Printmiller
Read out

Small but tough: In Alaska, paleontologists have discovered the fossil of a 69 million year old marsupial. The only a few centimeters large creatures lived in the midst of numerous dinosaurs, as bone finds prove. However, the special feature: This marsupial is the northernmost discovered. During his lifetime, the site was even closer to the North Pole - and it remained dark for four months.

Although the climate during the Cretaceous period was much warmer than it is today, even then Alaska was not a very comfortable place to live: it stayed dark for months in the winter and snow was falling more frequently. For a long time paleontologists considered this area to be sparsely populated at most. All the more surprising was the discovery of thousands of dinosaur fossils in the far north several years ago. In 2018, researchers came across traces of two dinosaur species that had never been found together.

Northernmost known marsupial

Now it turns out that the Cretaceous wildlife of Alaska was even more varied than previously thought. Jaelyn Eberle of the University of Colorado's Museum of Natural History and her team have also discovered numerous fossils of marsupials there for the first time. It is the remains of about 60 specimens of only a few centimeters in size, which lived about 69 million years ago.

Search image with Dinos: The excerpt shows a reconstruction of the mini-prey Unnuakomys hutchisoni. © James Havens

The Unnuakomys hutchisoni baptized species is thus the northernmost known marsupial species ever, as the researchers report. During the lifetime of these animals their habitat was at the 80th parallel and thus beyond the Arctic Circle. The Unnuakomys, which resembled a small opossum, probably fed on insects and plants and had to cope with about four months of permanent dark.

Special adjustments?

The paloontologists speculate that the little Beutler had special adaptations in behavior or physiology that would allow him to survive so far in the far north. "The sheer frequency of Unnuakomys hutchisoni at the site suggests that this tiny marsupial thrive in the Arctic environment, while the climatic extremes seem to have acted as a biogeographical barrier for other marsupials, " she says The researchers say. display

In their opinion, these new discoveries prove that the high north at that time had a much more diverse wildlife than had long been assumed. "North Alaska was not only inhabited by a whole range of dinosaurs. The fact that we now find new types of mammals gives completely new insights into the ecology of the time, "says co-author Patrick Druckenmiller of the Alaska Museum of the North. "With each new species we get a new picture of this primeval polar landscape." (Journal of Systematic Palaeontology, 2019; doi: 10.1080 / 14772019.2018.1560369)

Source: University of Alaska Fairbanks

- Nadja Podbregar