5. Cave Bear
Ursus spelaeus, also known as the cave bear, was a common species of bear that lived during the Pleistocene era. It became extinct during the Last Glacial Maximum 24,000 years ago. This mammal gets its name because most of its fossils have been found in caves. Experts believe this species spent much more time in caves than their modern counterparts.
The cave bear descends from the Etruscan bear, which lived during the Plio-Pleistocene era. Cave bears are the ancestors of our modern brown bears and polar bears. Analysis of the cave bear’s teeth shows that they survived on a mostly vegetarian diet. These mammals weren’t shaped too differently from modern bears and had a similar skeletal structure. Their average weight was 770 to 1,320 pounds. Cave bears tended to have many health issues, and most of them lived less than 20 years.