These are the miacids, the ancestors of all modern predators, which appeared some 50 million years ago. Miacids have retained their similarity to their insectivorous ancestors: small, short-legged, with long bodies and narrow, outstretched snouts. However, their skulls were larger and their brains are thought to have been more complex. They had well-developed hearing and vision, as well as locomotion combined with quick reaction and strength.
The miacids later became the ancestors of the ten families of carnivores that exist today.
Three families – eared seals, true seals and carnivores – have returned to the sea and are still living there. The families that stayed on land – raccoon, bear, dog, porpoise, veery, hyena and cat – became slightly faster and more observant than their ancestors, and developed a more sensitive sense of hearing and smell.
About 10 million years ago, the first cat predators evolved from miacids – individuals that successfully adapted to their living environment. Their size was that of a lynx and they closely resembled modern cats, differing only in having longer fangs and smaller brains.The ancestors of the three branches of the modern cat family (small cats, stable cats, and cheetahs) are neophelids. Along with the neofelids, the peliofelids have also emerged, distinguishing two groups – the nimravidus and the ancient sabre-toothed cats, which survived for around 30 million years. Neophelids evolved further and somewhere around 20 million years ago the pseudaleur appeared, which was very strong and fast for its size. Like modern cats, it was also able to hunt smaller animals.
The descendants of the Pseudaleurs were divided into two groups: the first included the ancestors of the fast and flexible modern cats, and the second included the heavier and slower animals that were adapted to hunt the larger herbivores of the time. The most famous of all known fossil predators, the famous Ice Age Cruciferous Tiger, belongs to this branch of the cat family. The largest sabre-toothed cats had tusk lengths of more than 20 cm. When the jaws closed, these two curved daggers, protruding from the upper jaw, rested on the sides of the lower jaw.