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.
South German Jurassic South German Jurassic The term South German Jurassic () in earth history is used to refer to a lithostratigraphic rock unit at the hierarchical level of a super group. The rocks of the South German Jurassic were mainly deposited during the Jurassic period about 199 to 146 million years ago. The boundaries of the South German Jurassic and those of the chronostratigraphic or international Jurassic are not, however, exactly coincident. The depositions began rather later than the date of the international Triassic/Jurassic boundary and end as a result of erosion of the uppermost strata at various times during the Upper