The origin of tigers is very unclear. The reason is that our knowledge is based on climate change data and very few fossils that have been found in the northern hemisphere, mainly in Russia, China and Indonesia. As a result experts have a lot of disagreement on the exact origin of tigers. However, most experts believe that tigers originated in eastern Asia and spread to other areas from there. The South Chinese tigers, which has a more primitive skull shape than other tiger sub species, is believed to be the most original of all the tigers sub species.
It is generally believed that most of the modern mammalian carnivores originated from a primitive carnivore known as the Creodont, which emerged in the northern hemisphere in the Paleocene epoch about 55 million years ago. At that time the age of the large reptiles was long over and the stage was set for mammals to take over the earth.
Creodonts gradually evolved into a group called the Miacid carnivores. By the Eocene epoch, less than 50 million years ago, the miacids were widespread. They were small animals with a long body and short legs, resembling a mongoose. They were probably the first mammalian carnivores to develop teeth designed to tear and chew flesh or carnassial shear, a big evolutionary jump. Over millions of years as these early carnivores evolved, they diverged into two lines – the caniforms (ancestors of the modern day canids) and the feliforms (ancestors of the modern day felids). It was only in the last 20 million years or so that the mammalian carnivores started looking somewhat similar to the modern day carnivores.
The first modern cat is believed to be the Pseudaelurus that evolved around 20 million years ago. This pre historic cat is believed to be the ancestor of all the felines and the pantherines. However, it took another 17 million years for the modern day wild cats to be firmly established. Somewhere in between the appearance of Pseudaelurus and the establishment of the modern wild cats the ancestors of the modern wild cats spread to North and South America. From the study of the available fossils it is estimated that tigers, leopards and jaguars first appeared around two million years ago. By that time lions and cheetahs were already well established.
Until recently, it was widely believed that tigers originated in northern Asia and as the polar ice sheets spread southwards tigers moved into Central Asia China and then on to Southeast and South Asia. One major drawback in this theory is that it failed to explain why would a predator that evolved in snowed out northern Asia need stripes as an adaptation. The presence of striped indicated that tigers originated in a tall grassland habitat and not in snow covered north Asia.
It is now widely believed that tigers originated in Eastern Asia and from there diverged into two groups. One that spread in to Russia and Central Asia, right up to the Caspian Sea and the other that spread into Southeast and South Asia.
I must add that though these theories are based on available scientific evidence but they are still just theories. There is so much of gap in the available fossil evidences that the exact origin of tigers will always be shrouded in mystery.
