The Mesozoic Era, frequently referred to as the Age of the Giants, the Age of the Retiles, or the Age of the Dinosaurs began 240 million years ago and lasted until the well-known mass extinction 65 million years ago. This era, spanning 185 million years, is divided into three separate periods individualized by the introduction of new species of plant and animal life, numerous geological changes, and diverse climates.
During the first period, known as the Triassic Period, the planet we know today began to take shape. The world’s one large land mass, called Pangaea, began to separate due to movement of the earth’s tectonic plates located under the earth’s crust. The period began with a warm and arid climate, yet experienced temperature extremes due to the low sea level. The areas closest to the oceans would have had adequate rainfall, whereas the interior of the land mass was most likely a desert environment due to the far distance from the sea. Plant life, such as seed ferns and conifers flourished as insects, reptiles, frogs, and crocodiles, that had survived the previous Permian extinction, became dominate. The first mammals and small dinosaurs, such as plesiosaurs, appeared on the scene.
The Jurassic period brought rising seas as the large land mass continued to break apart. Frequent rains and flooding found the interior land changing from a vast, barren desert to a life-supporting, tropical environment. The warm, wet climate created lush forests which amply supported herbivores such as Stegosaurus. Dinosaurs became larger and began to rule in areas now known as Colorado and Utah. Fossils of these giant plant eaters have been found with Allosaurus, a vicious carnivore, not far behind.
Dinosaurs reigned supreme during the Cretaceous period. The seven continents were visible and from the warm, wet climate emerged flowering plants such as magnolias and lilies. Ants, butterflies, and termites also entered the scene. However, the temperature worldwide did not experience much change, a fact scientists still find perplexing. According to Paleous.com, the temperature in the beginning of the Cretaceous period from the Northern Hemisphere to the Southern Hemisphere was basically unchanging and approximately ten degrees higher than temperatures today. During the late Cretaceous, the areas near the equator became extremely hot. Land near the oceans, that would ordinarily be assumed to be wet and humid, became unreasonably dry. Polar ice caps and glaciers were also non-existent. There is still much debate in the scientific community on the climatic changes during this period, but all agree that herbivores, such as Triceratops, and carnivores, such as Tyrannosaurus, thrived in the climate of North Western America, Canada, and China.
Earthquakes and volcanoes during the era were frequent and active shaping the landscape we view today. Large amounts of gases and ash that spewed into the atmosphere would have also had a huge affect on the weather conditions. During these times, plant life would expire in affected areas forcing the land animals to migrate in search of food and better conditions for survival.
At the end of the Cretaceous period and after the mass extinction of the dinosaurs, the earth became dominated by mammals. The continents were formed, volcanoes and earthquakes had created mountain ranges, new species appeared and plant life became abundant. The climate became cooler leading to the ice age which occurred approximately 20,000 years ago. One can only guess at the changes and extinctions that loom in the future.