Читать книгу Oceans For Dummies - Joseph Kraynak - Страница 59

The Jurassic period (from 201.3 to 145 million years ago) is everyone’s favorite (thank you Michael Crichton and Jeff Goldblum!). Because you’ve probably seen the movie, we’ll keep it simple … ish. During this period:

 Ornithischians (vegetarian dinosaurs with bird hips) begin to spread and diversify.

 Adaptations to leg and pelvic bones allow for a larger gut and, hence, larger teeth to help fill that gut, ultimately resulting in larger dinosaurs.

 Megazostrodon, the first true mammal appears, but unfortunately it’s as ugly as today’s possums … even though they are kinda cute.

 Some mammals become aquatic (such as the castorocauda, a beaverlike critter) and some take to the air (such as the volaticotherium, similar to today’s flying squirrels, definitely cute).

 Paravian dinosaurs appear, sporting feathers in place of scales (très chic), becoming, unbeknownst to them, ancestors of modern birds.

 Large marine reptiles rule the seas as main apex predators (top of the food web with nothing big enough or mean enough to eat them). These marine reptiles include plesiosaurs and ichthyosaurs (which look like plesiosaurs without necks) and, later, pliosaurs (close cousins of ichthyosaurs) and marine crocodiles.

 Diverse ecosystems develop complete with ammonites, gastropods, and fish.

 Freshwater turtles put in an appearance.

The Jurassic period ended with a relatively minor extinction event (what a disappointment). Pangea continued to go to pieces, and sea levels began to rise, creating shallow seas in North America and Europe. These rising seas coupled with a change in climate caused by an increase in volcanic activity in the Pacific may have been the cause.