EXTINCTION

There were several large extinction events during the Cretaceous, each millions of years apart. Some of the species and genera types that became extinct during the Cretaceous included the Allosaurs, the iguanodonts, many of the sauropods, and many other species. The interesting story of extinctions is not always how the extinction occurred, but what animals stepped into the empty places and replaced the extinct creatures. Allosaurs gave way to the Tyrannosaurs and Spinosaurs, and hadrosaurs and ceratopsians replaced iguanodonts and sauropods.

Dramatic volcanic and geologic activity contributed to many of the extinctions During this time period, the Earth was undergoing dramatic changes and much of that change was due to extensive volcanic and geologic activity. This activity played a large role in many of the extinctions. Some extinctions were localized on a single continent and some occurred worldwide. Volcanic activity in particular can be quite catastrophic, causing death and destruction over many thousands of square miles. Destruction on this scale could easily wipe out an entire species. The drifting continents also would have contributed to extinctions as many species may have been cut off from traditional food supplies and could not adapt to their news environments.

Dinosaurs vanish Of course, the biggest extinction of the Mesozoic - the event that ended the Mesozoic - occurred when a comet or asteroid struck the Earth 65 million years ago and impacted at what is now the Yucatan Peninsula in Mexico. This event may not have been the single event that ended the age of dinosaurs, but it was probably the most important component of the extinction. The asteroid striking the Earth most likely sent enough smoke and ash into the atmosphere to block out the sun for over a year - long enough to kill almost all plant life and therefore deprive many animals of food and causing whole species to starve to death.