Cats have a similar biology to that of Humans; they often walk on two legs, have opposible thumbs, and stand up straight. Dissimilarly, they have tails, pointy ears, excellent night vision, and stand at about 3 feet tall. Cats are fastest and most-stable on all four limbs, but most choose to appear civilized by walking upright.
Cats are primarily carnivores, and most view their hunting skills as a form of pride. Cats who do not hunt are often regarded as outcasts.
After footage of a domestic cat giving what seemed like a thumbs up circulated around Cradle, people began to breed cats with the intent of bringing out latent polydactylism, in order to replicate this amazing mutation. Soon enough the vast majority of cats born and bred on Cradle had an opposible digit rarely found in their ancestry only a few decades ago.
June 27, 2127 marked the birth of the first Cat with the ability to respond to external inquiries, a.k.a. a foreign language. Ironically, his name was. It wasn't long before its offspring were bred, then their offspring, and soon, Cats as Cradians had known them had vanished, leaving in their wake a new race of highly-intelligent Domesticated Cradians (often referred to as D-Cats or just simply Cats, though this term has been known to be offensive in certain circles).