 Biogeographical Evidence:  The following website introduces the biogeographical evidence and shows the movement of the continents from Pangaea (the earliest supercontinent from which all continents arose) to present day Pangaea - ZoomSchool.com

 Pangaea broke into 2 smaller supercontinents during late Triassic.  Evidence of common Plant life and animal life can be found on all continents, giving support to this theory – eg. Glossopteris (fossil fern) found on every southern continent – India, South America, Australia, Antarctica, and Southern Africa

 First aquatic reptile, Mesosarus, (lived before the dinosaurs) fossils were found in both South Africa and South America, supporting the theory  Seven “missing link” fossils Seven “missing link” fossils

 There was a mass extinction at end of Permian Period (last period of Paleozoic, right before Jurassic Period)  During the Triassic, Jurassic and Cretaceous (periods of the Mesozoic Era) many new species were formed  Triassic: Dinosaurs, Mammals, flying reptiles, amphibians  Jurassic: birds

 at the end of the Cretaceous period (called the K – T extinction), which wiped out 85% of all species including the dinosaurs  65 mya  The K-T Extinction was the second largest  Called K – T because it occurred at the boundary of the Cretaceous and Tertiary periods, K is used for Cretaceous

The cause of the mass extinction is generally believed to be a meteorite colliding with earth.

 Evidence supporting the meteor or comet showers theory  A layer of sediment deposited at that time in Earth’s history contains incredibly high amounts of Iridium  Iridium is found only in Earth’s mantle and in outer space  Volcanic eruptions are another viable theory due to Iridium in Earth’s mantle