The Age of Reptiles (and dinosaurs) The Mesozoic Era The Age of Reptiles (and dinosaurs)

The Mesozoic Era is divided into 3 periods, the Triassic, the Jurassic, and the Cretaceous Ammonite fossils are used as index fossils to date sedimentary rock layers from the Mesozoic. Changes in ocean environments during the Mesozoic led to many different types of ammonites that existed for short periods of time

Mesozoic Earth: Pangea formed during the Permian and lasted into the Jurassic when continents began to shift and break into the continents we see today. The continental drift that lead to the breakup of Pangea is still happening today

The Triassic Period Pangea continued as a single, large landmass through most of the Triassic period. After a slow recovery from the Permian extinction, many kinds of reptiles evolved. Late in the period, the first mammals appeared.

Reptiles were dominant on land and in the sea Ted Ed: The Game Changing Amniotic Egg The first dinosaurs evolved from reptiles in the early Triassic Dinosaurs would not be very diverse until the Jurassic

Herrerasaurus

Pterosaurs

Ichthyosaur

Pachypleurosaurus

Gymnosperm plants became common The first mammals evolved from mammal-like reptiles in the late Triassic First mammals were small, rodent like, and ate insects. Gymnosperm plants became common Gymnosperms have seeds without a protective coating These plants are able to reproduce without a pool of water

Megazostrodon Adelobasilus

The Jurassic Period Pangea continued to split apart during the Jurassic period. Many kinds of dinosaurs evolved and became widely distributed.

Hadrosaur

Brachiosaur

Allosaurus and Stegosaurus

Continental drift had caused seas to form in between continents making climates on land less harsh Fish with scales and fins like modern fish evolved in the seas

Dinosaurs developed into a varied and widespread group They became the dominant land animal Bird-like dinosaurs with feathers evolved These dinosaurs could not fly, but were able to glide Ted Ed: How Did Feathers evolve?

Archeopteryx and Pterosaur

The Cretaceous Period The cretaceous is named for the enormous chalk deposits found in Europe The formed chalked formed by tiny plankton during this period. “Creta” means chalk in Greek.

A greater diversity of life forms evolved during the Cretaceous period A greater diversity of life forms evolved during the Cretaceous period. Dinosaurs, birds, flowering plants, and small mammals all flourish.

Dinosaurs continue to dominate land Reptiles continued to flourish Giant snakes Early Crocodiles that were up to 12 meters long

Triceratops

Tyrannosaurus rex

Mammals continued to diversify

Angiosperm plants with flowers appeared on land - Flowering plants like willow, birch, and sassafras evolved during the cretaceous and are still found today