The Mesozoic Era

1884 WordsApr 6, 20178 Pages
Introduction The Mesozoic Era began around 250 million years ago and ended 65 million years ago. It is divided into three different periods, The Triassic, The Jurassic and The Cretaceous. In the Mesozoic Era Earth was extraordinaly different from what it is now. The climate was humid and tropical, the sea levels were constantly changing and even the shape of the Earth 's continents were different (Benson et al, 2010). The land was dominant by the dinosaurs but the oceans were populated by more rich and diverse marine reptiles. There were more than a dozen different groups of marine reptiles in the Mesozoic era, these groups contained pelagic and coastal predators and coastal herbivores. The three main predators of the oceans were the…show more content…
During the Late Triassic period they reached their highest diversity, they became more advanced and specalized, making them one of the top Marine predators. Ichthyosaurs over time evolved to have streamlined, fish-shaped bodies and large heads. They also evolved to have thicker bodies and a thicker backbone which meant they swam more with a convergent motion (Callway, 1997). They had the largest eyeballs (up to 264mm in diameter), of all vertebrates which were supported by a ring of sclerotic bones, these eyes were adapted to help them find prey in low light environments (Motani, 2009). Ichthyosaurus also had large ear bones, scientists believe this was an adaptation that allowed them to locate their prey by listening for their arrival through the water . This adapation was also a useful way for them to listen for predators that may be approaching (Fisher et al, 2016). The most distinguishable feature of their body plan was the presence of the caudal fin and the dorsal fin which was formed of stiff tissue, not bone. The first whole fossil of an Ichytosaur was discovered 200 years ago by Mary Anning on the Jurassic coast of Dorset at Lyme Regis. Mary Annnings brother, Joseph found the skull of an Ichthyosaur in 1811 between the cliffs at Lyme Regis and Charmouth but failed to find the rest of it. Mary went out found the remainings of this fossil a year later, she found the rest of the fossil at Lyme Regis. This fossils skull was around 1 meters long and the whole
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