What is the longest living land animal on earth?

Most animals found today are evolved forms of past species. For example, modern man has only existed for about 12 thousand years. However, recent discoveries have traced back human ancestry as far as some of the first organisms to ever exist, ancient fish-like beings. Through many, many millions of years, animals can evolve to become very different things. Here's another one: the closest living relative to the mighty Tyrannosaurus Rex? Domestic chickens.