Evolution of animals merely depends upon environmental conditions of Earth. When digging down the history of Earth, we can see some animal species manage to thrive upon THE different geological time span of Earth, developed before million of years ago. Here the list of top 10 oldest animal species on Earth.

10 Martialis Huereka-120 million years old
see all list and pictures http://www.edailynet.com/unbelievable-top-10-oldest-animal-species/