Millions of years ago, peculiar beings ruled the Earth. The Earth back then looked very different from what we call “Earth” in the present day. Even though the world fauna had been drastically changed from that which had been seen in the Paleozoic, that was not the only major occurrence. The Mesozoic era is sometimes called the age of reptiles. Mesozoic means “middle animals”, and dinosaurs were conceivably the most typical organisms in the Mesozoic. The Mesozoic is sectioned into three periods: Triassic, Jurassic, and Cretaceous. The dinosaurs had evolved in the Triassic period, however, they were not very diverse until the Jurassic. The world’s life forms were very different during this era than either before or after. The Mesozoic era extends …show more content…
There were also other groups that lived in the Mesozoic era. Reptilian groups, such as the sphenodontia group today, which only includes one species-- the tuatara of New Zealand, dwelled in this era. “Fossil crocodyliforms from the Mesozoic often resemble the currently existing species called crocodilians. This includes crocodiles, alligators, and gharials” (pg 49 A Guide to Dinosaurs). “It is true that many of the crocodyliforms that are from the Mesozoic appear to have been “crocodile-shaped,” but stating that they have remained unchanged to the present day would be incorrect” (pg 49 A Guide to …show more content…
Before this extinction, many giant sauropods lived during the late Jurassic period, and conifers dominated the landscape. During the extinction, the majority of the stegosaurid and enormous sauropod dinosaurs died out, as did many genera of ammonoids, marine reptiles, and bivalves.
More than 80% of marine bivalve species and many other shallow-water species perished. This was a minor mass extinction, yet the cause of this extinction is still unknown. A theory has been put into place that it was triggered by the release of huge methane deposits from within the Earth. These deposits had formed beneath the seabed as surface algae dies and sinks to the sea floor.
The last period in the Mesozoic era was the Cretaceous period. This was a flourishing time for the dinosaur population. Carnivorous dinosaurs, as in the Tyrannosaurus rex and the Giganotosaurus, made their way into the picture. The Triceratops and many other species came into sight as well. Mammals had made their appearance as a thriving genus, and flowering plants were developing as well as exceedingly altering the