Jurassic Period Phanerozoic

rhamphorhynchus

the jurassic ranges 200 million years 145 million years, , features 3 major epochs: jurassic, middle jurassic, , late jurassic.

the jurassic epoch spans 200 million years 175 million years. climate more humid triassic, , result, world tropical. in oceans, plesiosaurs, ichthyosaurs , ammonites dominanted seas. on land, dinosaurs , other reptiles dominated land, species such dilophosaurus @ apex. first true crocodiles evolved, pushing large amphibians near extinction. reptiles rose rule world. meanwhile, first true mammals evolved, never exceeded height of shrew.

the middle jurassic epoch spans 175 million 163 million years. during epoch, reptiles flourished huge herds of sauropods, such brachiosaurus , diplodicus, filled fern prairies of middle jurassic. many other predators rose well, such allosaurus. conifer forests made large portion of world s forests. in oceans, plesiosaurs quite common, , ichthyosaurs flourishing. epoch peak of reptiles.

artist’s 1901 depiction of stegosaurus (inaccurately portrayed dragging tail).

the late jurassic epoch spans 163 million 145 million years. late jurassic featured massive extinction of sauropods , ichthyosaurs due separation of pangaea laurasia , gondwana in extinction known jurassic-cretaceous extinction. sea levels rose, destroying fern prairies , creating shallows. ichthyosaurs became extinct whereas sauropods, whole, did not; in fact, species, titanosaurus, lived until k-t extinction. increase in sea-levels opened atlantic sea way continue larger on time. divided world give opportunity diversification of new dinosaurs.