Ancient kinship: how dogs and cats evolved from a shared carnivore ancestor
Dogs and cats diverged from early carnivoran ancestors about 42.5 million and 30 million years ago, respectively. The first true dog, Hesperocyon, appeared in North America, while the first true cat, Proailurus, arose in Eurasia. Both lineages trace back to miacids, early carnivorans, and all mammals share a Last Universal Common Ancestor (LUCA) from about 4 billion years ago. Genetically, humans are slightly closer to cats in chromosome arrangement than to dogs.