Back home, Amphicyonidae (bear-dogs) predated Ursidae by only four million years. While the latter still lives in the form of eight species, the former had been extinct for two-and-a-half million years, which made me suspect that the ice ages were what drove the bear-dogs into extinction.
But in an alternate Earth, Ursidae never existed, and Amphicyonidae instead occupied that niche. In order to understand the bear niche, we need to recognize these key factors among bears:
- Large, dexterous paws that can articulate to the extent of climbing and swiping, more like cats than dogs
- A large brain necessary to learn new things (like the blacks, browns and polars becoming more and more accustomed to urban life)
- Omnivory (Blacks and browns, for example, are hypocarnivorous, meaning that meat makes up a maximum of 30% of their caloric intakes)
In an alternate Earth with no ursids, would some species of amphicyonids evolve to look and behave more like them, maybe even survive the Pleistocene ice ages?