Sharks have lived on the earth longer than almost any other animal – 450 million years – surviving mass extinctions and every other environmental hazard. 3,000 species have lived over a period of nearly half a billion years – making them an evolutionary success story. Silurian Period: 450 M...
Mass extinctions near-Earth object: impactThe impact of a near-Earth object 66 million years ago in what is today the Caribbean region, as depicted in an artist's conception. Many scientists believe that the collision of a large asteroid or comet nucleus with Earth triggered the mass extinction...