<em>Two or more species share a unique physical feature,</em> for example, an unpredictable bone structure or a body plan, they may all have acquired this component from a typical predecessor.
Physical highlights shared because of developmental history (a typical progenitor) are said to be homologous.
<em>The front flippers of whales and the forelegs of four-legged vertebrates like canines and crocodiles are completely gotten from the equivalent tribal tetrapod structure.</em>
