A tiny fossil found in Pennsylvania, may be the oldest example of bones "hands." This humerus age of 360-370 million years indicates that the limbs of animals may have evolved for use in water, and not to go over the ground.
The earliest animals with limbs were fish that live in shallow rivers, but their place on the evolutionary tree — is far from clear.
The process which converted fins limb still poorly understood, despite the fact that it is one of the key episodes earth evolution.
Dr. Ted Deshler (Ted Daeschler) of the Academy of Natural Sciences in Philadelphia (Academy of natural sciences) compared the finding with the Rosetta stone (with which deciphered Egyptian hieroglyphics). It will help to understand the transition between fish and tetrapods.
Americans believe that the nameless animal, still known only at number ANSP 21350 was a predator ambush.
And it's being used limbs to be sustainable in the flow of the stream or small river. Only further this limb was used to move the animal through the shallow water.