Cats and dogs are with us today; that is, they’re domesticated animal members of the human family.
But they are also predators by nature, just like their wild relatives, which include but aren’t limited to lions, tigers, wolves, and bears.
These particular members of the order Carnivora all have claws, fangs, and powerful hunting instincts, but a few others get by without such tools. This is why biologists trying to classify animals look for a set of specialized meat-slicing teeth (called carnassials) that all carnivorans have.
That’s just step #1. The boffins then must file each of the world’s 280-plus carnivoran species (and over 350 fossil groups) into one of Carnivora’s two natural suborders: feliform and caniform.
“Form” here doesn’t refer to the animal’s outward appearance. It involves some dental features as well as certain cranial structures around the ear and skull base that only a zoologist or paleontologist could love.
These anatomical details are all one way in cats and other feliforms and all another way in caniforms, including dogs.
Scientists don’t understand why such a difference exists. But they do know that it has been around for more than 60 million years.
Do cats and dogs go back to the K/T extinction?
Short answer: No, but Carnivora probably does (its origin story isn’t completely known yet). However, while early small, weasel-like carnivorans already had some feliform/caniform distinctions, they had to play second-fiddle to a group of apex predators called creodonts for tens of millions of years.
Details: Today, Feliformia includes hyenas, oddly enough, as well as civets, meerkats and other mongooses, Asiatic linsangs, and a few other groups in addition to the cat family Felidae.
A young Asiatic linsang:
Caniforms other than dogs include, but aren’t limited to, bears, raccoons, skunks, weasels, foxes, otters, badgers, and (believe it or not) seals and walruses.