Cretaceous

The Cretaceous is a major division in Earth's geological history. It began approximately 145 million years ago and ended approximately 66 million years ago. It is the last of the three periods of the Mesozoic Era (Triassic, Jurassic, Cretaceous) and is the longest period recognized in geological science.

The name derives from the Latin word creta, meaning chalk or limestone. This is because extensive chalk layers—such as those visible along the coasts of England and northern France—formed during this period, composed of the accumulated remains of tiny marine organisms with shells.

Continents and climate

The supercontinent Pangaea continued to break apart during this period. Gondwana fragmented: Africa and South America drifted apart, and the Atlantic Ocean continued to widen. India began its journey northward. Temperatures were generally elevated, and ice was scarce at Earth's poles; sea levels were higher than today, creating shallow seas between continents.

Life

Dinosaurs remained the largest land animals, including famous species such as Tyrannosaurus and Triceratops. The seas were inhabited by marine reptiles and ammonites (coiled-shell organisms). Early birds continued to diversify. This period also saw the rise of flowering plants (angiosperms), which transformed the appearance of global vegetation and was linked to the evolution of pollinating insects.

End of the period

The Cretaceous ended with a mass extinction event known as the Cretaceous–Paleogene extinction (K–Pg), which eliminated non-avian dinosaurs and a large portion of marine life. The prevailing view is that a large meteorite struck the Gulf of Mexico—the Chicxulub crater—causing dust and rapid climate change. This is also linked to the Deccan volcanic activity in India.