Original: It is an example from several lines of ancient sarcopterygian fish developing adaptations to the oxygen-poor shallow-water habitats of its time , Jennifer A. Clack , Scientific American , Getting a Leg Up on Land Nov. 21 , 2005 .
Simplified: Tiktaalik ( ) is a genus of extinct sarcopterygian ( lobe-finned ) fish from the late Devonian period , with many features akin to those of tetrapods ( four-legged animals ) .