Mesozoic Era Phanerozoic

1 mesozoic era

1.1 triassic period
1.2 jurassic period
1.3 cretaceous period

mesozoic era

the mesozoic ranges 252 million 66 million years. known age of dinosaurs , mesozoic features rise of reptiles on 150 million year conquest of earth on land, in seas, , in air. there 3 periods in mesozoic: triassic, jurassic, , cretaceous.

triassic period

the triassic ranges 250 million 200 million years. triassic desolate transitional time in earth s history between permian extinction , lush jurassic period. has 3 major epochs: triassic, middle triassic , late triassic.

the triassic lasted between 250 million 247 million years ago, , dominated deserts pangaea had not yet broken up, interior arid. earth had witnessed massive die-off in 95% of life became extinct. common life on earth lystrosaurus, labyrinthodonts, , euparkeria along many other creatures managed survive great dying. temnospondyli evolved during time , dominant predator of triassic.

plateosaurus (a prosauropod)

the middle triassic spans 247 million 237 million years. middle triassic featured beginnings of breakup of pangaea, , beginning of tethys sea. ecosystem had recovered devastation of great dying. phytoplankton, coral, , crustaceans had recovered, , reptiles began increasing in size. new aquatic reptiles, such ichthyosaurs , nothosaurs, evolved. meanwhile, on land, pine forests flourished, mosquitoes , fruit flies. first ancient crocodilians evolved, sparked competition large amphibians had since rule freshwater world.

the late triassic spans 237 million 200 million years. following bloom of middle triassic, late triassic featured frequent rises of temperature, moderate precipitation (10-20 inches per year). recent warming led boom of reptilian evolution on land first true dinosaurs evolved, pterosaurs. climactic change, however, resulted in large die-out known triassic-jurassic extinction event, in archosaurs (excluding ancient crocodiles), synapsids, , large amphibians became extinct, 34% of marine life in fourth mass extinction event. extinction s cause debated.

jurassic period


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.

cretaceous period

the cretaceous longest period in mesozoic, spans 145 million 66 million years, , divided 2 epochs: cretaceous, , late cretaceous.

tylosaurus (a mosasaur) hunting xiphactinus

the cretaceous epoch spans 145 million 100 million years. cretaceous saw expansion of seaways, , result, decline , extinction of sauropods (except in south america). many coastal shallows created, , caused ichthyosaurs die out. mosasaurs evolved replace them apex species of seas. island-hopping dinosaurs, eustreptospondylus, evolved cope coastal shallows , small islands of ancient europe. other dinosaurs, such carcharodontosaurus , spinosaurus, rose fill empty space jurassic-cretaceous extinction had created. of successful iguanodon spread every continent. seasons came effect , poles grew seasonally colder. dinosaurs such leaellynasaura inhabited polar forests year-round, while many dinosaurs, such muttaburrasaurus, migrated there during summer . since cold crocodiles, last stronghold large amphibians, such koolasuchus. pterosaurs grew larger species tapejara , ornithocheirus evolved. more importantly, first true birds evolved sparking competition between them , pterosaurs.

the late cretaceous epoch spans 100 million 65 million years. late cretaceous featured cooling trend continue cenozoic era. eventually, tropical ecology restricted equator , areas beyond tropic lines featured extreme seasonal changes of weather. dinosaurs still thrived new species such tyrannosaurus, ankylosaurus, triceratops , hadrosaurs dominated food web. pterosaurs, however, going decline birds took skies. last pterosaur die off quetzalcoatlus. marsupials evolved within large conifer forests scavengers. in oceans, mosasaurs ruled seas fill role of ichthyosaurs, , huge plesiosaurs, such elasmosaurus, evolved. also, first flowering plants evolved. @ end of cretaceous, deccan traps , other volcanic eruptions poisoning atmosphere. continued, thought large meteor smashed earth, creating chicxulub crater creating event known k-t extinction, fifth , recent mass extinction event, during 75% of life on earth became extinct, including non-avian dinosaurs. every living thing body mass on 10 kilograms became extinct, , age of dinosaurs came end.