Late Cretaceous

The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs in the Cretaceous Period. This time was important for learning about Earth's history. Many animals and plants lived and changed then.

Rock layers from this time are called the Upper Cretaceous Series. The name Cretaceous comes from creta, a Latin word for white limestone called chalk. Famous chalk cliffs, like those in northern France and the white cliffs of south-eastern England, formed during this period. Studying the Late Cretaceous helps us learn about the world long before humans existed.

Climate

See also: Cretaceous Thermal Maximum

During the Late Cretaceous, the Earth was warmer than it is today. But it was slowly becoming cooler. Very warm areas, called the tropics, were only near the equator. Places farther north began to have more seasons.

Geography

Earth's plates moved, and the Americas drifted west. This made the Atlantic Ocean larger. The Western Interior Seaway divided North America into Appalachia and Laramidia. India moved north toward Asia. In the Southern Hemisphere, Australia and Antarctica were connected but began to drift away from Africa and South America. Europe was made of many islands, and some of these islands had small dwarf dinosaur species.

Vertebrate fauna

In the Late Cretaceous, many kinds of dinosaurs lived around the world. In places like western North America and eastern Asia, hadrosaurs, ankylosaurs, and ceratopsians were common. Large predators called tyrannosaurs were top hunters in North America. Other dinosaurs like pachycephalosaurs were also found there.

In a region called Gondwana, different dinosaurs lived, including abelisaurids and titanosaurs.

Birds were becoming more common, evolving into many shapes and sizes. Some could fly, while others, like marine Hesperornithes, lived in the ocean. Pterosaurs, flying reptiles, were still around but not as common as birds. Mammals were small but lived in many ways. In the oceans, new large sea reptiles like mosasaurs appeared, along with sharks and plesiosaurs.

Flora

Near the end of the Cretaceous Period, flowering plants became more common. In cooler areas, we could find many plants we recognize today, like magnolias, sassafras, and roses.

Cretaceous–Paleogene mass extinction discovery

Main article: Cretaceous–Paleogene extinction event

The Cretaceous–Paleogene extinction event was a big event that happened about 66 million years ago. Many animals and plants disappeared quickly. This event ended the Mesozoic Era and began the Cenozoic Era.

Scientists think a huge space rock hitting Earth and many volcanoes erupting may have caused this change. These events made it hard for many living things to survive.