The fossil specimens were found over three decades ago. A new study has identified the fossils as belonging to a group of now extinct mammals that are being recognized as "bear dogs". Scientists believe that these animals were prevalent tens of millions of years ago and lived in Europe, Asia, and North America.
According to the study, the bear dog is likely to have originated in southwest Texas and this was also a likely hot spot of evolution for the species. It is not known for certain, however, when or where the amphicyonid evolved.
The fossil findings indicate that the bear dogs weighed only a few kilograms and were the size of a Chihuahua at their first appearance on the planet. As they evolved, however, some members of this species of carnivorous animal grew to the size of modern day bears and became top chain predators in their respective ecosystems.
The bear dog is scientifically recognized as the amphicyonid. Their name is derived from their resembling a mix between the modern version of bears and dogs. Although the bear dog is seemingly like both modern bears and dogs in body shape and posture, they are not closely related to either animal.
According to Susumu Tomiya, a vertebrate paleontologist at The Field Museum of Natural History in Chicago, Illinois,neither bears nor dogs had evolved when the amphicyonid first appeared approximately 40 million years ago.