The cretaceous period is known as the time in the Earth’s history when the dinosaurs roamed the land. It was a time in which many new species came into existence, and when differences from region to region made the planet look more like it does today. The late cretaceous period saw most of the most extreme changes and was the time when the controversial event that wiped out the dinosaurs occurred.
When Was the Late Cretaceous Period?
The word cretaceous comes from the Latin word for “chalk” The geological evidence from the period does show an increase amount of chalk deposits in the rock formations. The late cretaceous period is a time span roughly 99.6 to 65.5 million years ago. The entire cretaceous period spanned from 145 to 65.5 million years ago. During the first few million years of this period, the climate remained similar to what it had been during the earlier Jurassic period. As the end of the period approached, however, climate changes caused a number of species to go extinct, while other types emerged.
The climate of Earth was generally warmer than it is now, though it did exhibit a generally cooling trend from earlier times. Tropical climates were restricted to the equatorial regions while northern areas exhibited more seasonal changes in temperature.
Climate changes caused the rise of new plant species like angiosperm flowers. In turn, this brought many new species of insects. Birds, reptiles and mammals diversified as well.
The Controversial Event
By the end of the cretaceous period, about half of the world’s species went extinct, according to experts. This is often referred to as the Great Extinction. Much of this change and replacement of species was occurring even before the “climactic event” that wiped out the dinosaurs. Scientists do know that something occurred in the late cretaceous period that caused severe and radical change in the environmental conditions that created an upset of significant proportions. It may have been a combination of an asteroid hitting the Earth and the volcanic eruptions that were happening at that period. Whatever the cause, the amount of sunlight hitting the Earth changed radically, and the great tropical regions that once covered the planet disappeared.
The Aftermath of the Great Extinction
Regardless of what event or combination of events created the change, the Earth was no longer able to support the huge reptiles called dinosaurs, and they rapidly died out. What followed was a rapid adaptation and evolution that saw the rise of many new species. These creatures were not as dependent on plant life for their survival. Instead, they lived on other animals. A variety of mammals arose that were adapted to survive in this new climate.
The late cretaceous period saw many changes that ultimately helped to create what exists today. The study of this important time in the Earth’s history has led to many important findings that tells people much about current conditions.