Mesozoic that would move into their current positions during the next era. The climate of the Mesozoic was varied, alternating between warming and cooling periods. Overall, however, the Earth was hotter than it is today. Dinosaurs appeared in the Late Triassic and became the dominant terrestrial vertebrates early in the Jurassic, occupying this position for about 135 million years until their demise at the end of the Cretaceous. Birds first appeared in the Jurassic, having evolved from a branch of theropod dinosaurs. The first mammals also appeared during the Mesozoic, but would remain small—less than 15 kg (33 lb)—until the Cenozoic.
Jurassic Coast period of 185 million years, and disclosing an almost continuous sequence of rock formations covering the Triassic, Jurassic and Cretaceous periods. The fossils found in the area and the coastal geomorphologic features of this dynamic coast, have advanced the study of earth sciences for more than two hundred years. The area covered by the designation comprises the land between the mean low water mark and the top of the cliffs or the back of the beach. The fossils found in abundance along this coastline provide evidence of how animals and plants evolved in this region. During the Triassic this area