CRETACEOUS PERIOD

How it started
Scientists are unsure exactly how the Jurassic period ended. They do know it ended with a mass extinction. That's how the Cretaceous period started.

Dates
The Cretaceous Period was the last and longest segment of the Mesozoic Era. It lasted approximately 79 million years, from the minor extinction event that closed the Jurassic Period about 145.5 million years ago to the Cretaceous-Paleogene (K-Pg) extinction event dated at 65.5 million years ago.

Climate
Temperatures in the Cretaceous time period it could get so hot it could cause flash fires. It is hypothesized that debris aerosols from the asteroid impact and the resulting fires may have combined with the ash and smoke from the continuing volcanic activity to significantly reduce global temperatures for a few decades. As a result of suddenly lowered temperatures there may have been a global disruption in the numbers of both land plants and plankton in the oceans.

ANIMALS

• Birds replaced pterosaurs in the air.
• The giant Sauropods, such as Apatosaurus.
• Theropods, including Tyrannosaurus rex
• Apex predators until the of end Cretaceous
• Tyrannosaurus Rex

Pterosaurs were flying reptiles of the clade or order Pterosauria. They existed from the late Triassic to the end of the Cretaceous Period. Pterosaurs are the earliest vertebrates known to have evolved powered flight.

Apatosaurus is a genus of sauropod dinosaur that lived from about 154 to 150 million years ago, during the Jurassic Period.

Tyrannosaurus rex meaning "king" in Latin), commonly abbreviated to T.rex, is one of the most well-represented of the large theropods.

PLANTS AND INSECTS

• Flowering plants develop
• Insects include: Bees, wasps, ants, and beetles
• Trees like Magnolia, ficus, and sassafras

Some Flowers
Mongolia
Archeafructus
Eudicots

Geography
The continents were in very different positions than they are today. Sections of the supercontinent Pangaea were drifting apart. The Tethys Ocean still separated the northern Laurasia continent from southern Gondwana. The North and South Atlantic were still closed, although the Central Atlantic had begun to open up in the late Jurassic Period. By the middle of the period, ocean levels were much higher; most of the landmass we are familiar with was underwater. By the end of the period, the continents were much closer to modern configuration. Africa and South America had assumed their distinctive shapes; but India had not yet collided with Asia and Australia was still part of Antarctica.

How it ended
Scientists think that there might have been an asteroid that caused the mass extinction. It had changed the climate so the plants and animals had all died.

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