Mesozoic geology. At the outset of the Mesozoic, all of Earth's continents were joined together into the supercontinent of Pangea (see the map of the Early Triassic). By the close of the era, Pangea had fragmented into multiple landmasses. The fragmentation began with continental rifting during the Late Triassic. During the Mesozoic, the Earth was very different than it is now. The climate was warmer, the seasons were very mild, the sea level was higher, and there was no polar ice. ... The Mesozoic Era lasted about 180 million years, and is divided into three periods, the Triassic, the Jurassic, and the Cretaceous.