Mr. Altorfer The Mesozoic Era Pages 378 to 384

 Geology of the Mesozoic Era  The Mesozoic era is divided into the Triassic Period, the Jurassic period, and the Cretaceous period.

The Mesozoic Landscape

 The dominant geological event of the Mesozoic era was the breakup of Pangaea.  Pangaea broke into two continents during the late Triassic period.  One of the continents was Gondwanaland, which included the future continents of South America, Africa, Antarctica, and Australia.  The Other continent was Laurasia, which included the future continents of North America, Europe, and Asia.

The Breakup of Pangaea

 The Climate during the Mesozoic era was warmer than the climate of the Paleozoic era. There were no ice caps, sea level increased, and narrow channels formed.  Throughout the Mesozoic era, North America drifted steadily westward. As North America hit a plate to the west, the Rocky Mountains formed.

Rocky Mountain Formation

 Mesozoic Life  Dinosaurs share a common ancestor with present-day reptiles such as the crocodile.  Dinosaurs and crocodiles differ in their hip structure.  Dinosaurs were dominant Mesozoic land vertebrates that walked with their legs positioned directly below their hips.

Dinosaur Hips

 Scientists hypothesize that some dinosaurs were more closely related to present-day birds than present-day reptiles. Some had wings, feathers, claws, and teeth.

 Dinosaurs were the dominant reptiles on land. Other types of reptiles lived in the sea and flew in the air.  Plesiosaurs were Mesozoic marine reptiles that had small heads, long necks, and flippers.  Pterosaurs were Mesozoic flying reptiles that had large bat-like wings.

Plesiosaurs

Pterosaurs

 Mammals evolved during the Mesozoic era, but remained very small.

 The mass extinction of that ended the Mesozoic era was called the Cretaceous extinction event.  Scientists hypothesize that a large meteorite hit Earth, creating large amounts of dust that blocked the sunlight.  Large volcanic eruptions could have added to the sunlight-blocking dust.  Without sunlight, plants died. Without plants, animals died.

Meteorite and Extinction