Research says climate change changed dogs from animals resembling cats to how they look today. Researchers say that 40 million years ago, dogs ambushed their prey like cats. The changing climate reduced the amount of forests in North America, so the shape and habits of dogs changed. New grasslands meant dogs had fewer places to hide to ambush their prey. They changed their hunting styles and grew longer legs.
Scientists looked at how dogs changed by looking at the elbows and teeth of species that lived up to 40 million years ago. The dogs' elbows and teeth clearly showed evolutionary change. Dogs used to have elbows like those of cats. The front paws swivelled so they could grab their prey. Elbows changed in dogs to let them run farther. This meant they could chase their prey over long distances. The teeth in dogs became harder so they could hold on to prey.