Mesozoic

The Mesozoic Era

Mesozoic, meaning "age of reptiles" was the period in time between 225 and about 65 million years ago. The subperiods included in this time period were the Triassic, Jurassic, and Cretaceous periods. You might recognize this as the age that the dinosaurs roamed the Earth.

At the time when the dinosaurs lived, Colorado was undergoing many geological alterations. Throughout most of the Mesozoic era, the supercontinent Pangea was beginning to break apart. Most of western North America, including Colorado, was affected by a series of mountain forming events called orogenies that deformed the North American continent with a series of uplifts. Nearby volcanic mountain ranges erupted frequently and spewed forth layers of ash and debris that covered many regions at a time. Many small ephemeral bodies of water, including lakes and ponds, constantly were formed and receded, leaving sedimentary deposits that recorded their history. These deposits created sedimentary rock formations such as the Chinle and Kayente During the Mesozoic era, North America was going north and through the northern desert belt, and Colorado was a subsequently arid lowland. The landscape was dominted mainly by mudflats. In western Colorado, rock formations similar to the Lykins were being distributed, bearing many different names.

Fossils are numerous in the Grand Valley from the Mesozoic Era. For example, at Rabbit Valley State Park, paleontologists have discovered //Camarasaurus// vertebrae and limb bones, //Diplodocus// central vertebrae and neural arches, and an //Iguanadon// skull. Western Colorado is reknowned (in the paleotoligical world) for its numerous Jurassic fossils, including //Stegosaurus, Brachiosaurus, Allisaurus, Ceratasaurus, Apatasaurus,// and //Utahraptor// fossils.