Origin - Page 1&2:
The Early Development Of The Carnivores | 3:
Origins Of The Tiger
Though it is still uncertain, the cat's early ancestors were probably primitive carnivores called Creodonts. These then may have evolved into a group of arboreal hunters known as the Miacid carnivores, and from this developed a diversity of animals; not only the cats of today, but also the walrus, seal, bear, dog, weasel, and others.
Creodonts lived in the Eocene period and encompassed the majority of the meat-eaters across Europe, Asia and North America. Ranging in size from weasel-like individuals, right up to bear-like animals, they were the first real advance along the path to modern Carnivora.
The largest fossil Creodont so far found is the hyaenodontid Megistotherium. About 20 million years ago this animal wandered the Sahara, weighing in at around 800 kilograms (1800 pounds) and with a skull twice the length of the tiger. This animal may hold the record as the largest-ever mammalian land predator.
At about this time the early carnivores started to appear and seem to have taken over from Creodonts, but what advantages carnivores held over Creodonts, and how one related to the other, we still don't really know. Both groups seem to have had the same ancestry, and though the Creodont had a smaller brain, this was similar to that of early carnivores.
The tooth arrangement among them was a little different. Creodonts were limited to meat eating, whereas the tooth arrangement of the carnivore allowed a more diverse diet, including one that contained, if meat was in short supply, a significant amount of vegetable matter.
A change in climate may well have favoured the early carnivores while adversely affecting the Creodonts. During the end of the Eocene period temperatures gradually lowered by 12 degrees centigrade and evergreen tropical rainforests were replaced by deciduous trees.
Early carnivores were called Miacids, and these were pretty unimpressive as carnivores go. They were at their peak during the late-Eocene and Oligocene periods around 60 to 65 million years ago.
Miacids were small and extremely vicious, with
short limbs, long bodies and lengthy tails. In appearance they
similar to our modern civets, (shown on this page), though much
Perhaps most disappointing
for todays carnivore fans was their diet. It consisted of bugs.
The Miacids went on to develop the carnassials. These are the tearing and chewing teeth well-developed in the modern cat. They consist of the fourth upper premolar and the first lower molar on each side and slice meat exactly like the blades on a pair of scissors. With the benefit of these new weapons, carnivores could now sheer chunks of meat from a carcass and their size increased.
Eventually the carnivores diverged into two main groups.
After millions of years these animals started to take on the look of the carnivores we see today.