The cretaceous period was between 145 to 66 million years ago.
What is the cretaceous period?
It was the last (third) and most prolonged period during the Mesozoic era (which started 252 to 66 million years ago, after a massive extinction event, that killed many animals, making way for the dinosaurs, and ended with another extinction event, which ended the era of dinosaurs) and began when the Jurassic period ended.
During the cretaceous period, there were significant inland seas and massive volcanoes. Huge ichthyosaurs and plesiosaurs ruled the oceans during this time. In addition, the planet’s atmosphere had three times more oxygen than it does now, producing more plants, and allowing for larger animals to exist.
Most of North America was underwater during this time, which allowed giant marine reptiles to grow. Inland, there were plants and dinosaurs such as the velociraptor.
The Cretaceous period ended with a mass extinction event called the K-Pg extinction event, which killed off 75% of life on Earth. Scientists assume that this extinction was caused by an asteroid impacting the planet, which would have thrown up dark dust that blocked out the sun for years, and stopped photosynthesis in plants and plankton worldwide. This would kill most large animals on land and in the oceans. The cretaceous period had ended.
The cretaceous period can be divided into 2 Subperiods.
The late Cretaceous was from 100.5–66 million years ago.
Maastrichtian (72-66 million years ago)
The Early Cretaceous was from 145 to 100.5 million years ago.
During this time, many new species evolved during this period that is still around today, including bryozoans, sharks, mollusks, fishes, turtles, and more!
The Cretaceous period was a fantastic time in our planet’s history, and it ended with a colossal extinction event that made way for the dinosaurs to become extinct. However, we now understand more about what happened during this time thanks to new studies of good fossils from the later part of this period.
The Cretaceous period is often called “the age of reptiles” and lasted 75 million years.