MPE - Mesozoic Era Lesson

 

Mesozoic Era

The Mesozoic Era is known as the "Age of Reptiles". Many reptiles were able to survive in the environment created at the end of the Permian era. Crocodiles, snakes, lizards, turtles, and the dinosaurs emerged during the Mesozoic era. The climate was so warm and tropical that glaciers did not form during this era. The Mesozoic Era is divided into three periods: Triassic, Jurassic, and Cretaceous. 

Triassic - 245 to 208 millions years ago

During the Triassic period, the first mammals evolved resembling small rodents. Other animals that developed included frogs, toads, and early crocodile like animals. The fiercest and most dominant animals were the dinosaurs.  Their ability to lay amniotic eggs on land versus water allowed dinosaurs to leave their eggs as they roamed forests full of gymnosperms like conifers and cycads. Fossil records tell us that gymnosperms, or cone bearing plants, were very common during the Triassic period.

Jurassic - 208 to 146 million years ago

Dinosaurs continued to evolve during the Jurassic period. "Lizard-hipped" and "bird-hipped" dinosaurs emerged. The Brontosaurus was a type of "lizard-hipped" dinosaur. The Stegosaurus was a type of "bird-hipped" dinosaur. Reptiles that could fly also evolved during the Jurassic period. The pterosaurs had skin covered wings whereas some dinosaurs had feathers.  The Archaeopteryx was one of the early ancestors of birds that exist today. The fossil remains of the small feathered dinosaur indicated that it had reptilian teeth, claws on its wings, and a tail.

Cretaceous - 146 to 65 million years ago

The earliest flowering plants, angiosperms, evolved during the Cretaceous period. Maples, oaks, magnolias, and willows were some of the most common types of trees during this period. Snakes and crocodilians evolved during this time as well. Dinosaurs continued to evolve including the Tyrannosaurus Rex. The T-Rex was one of the major dinosaurs to dominate the Cretaceous period. It had huge jaws, sharp teeth, and stood up to 6 meters tall. The horned Triceratops, the enormous Apatosaurus, and the duck-billed Hadrosaurs were some other common Cretaceous dinosaurs.

A mass extinction occurred at the end of the Cretaceous period. All of the dinosaurs, ammonites, and many large land animals became extinct.

The impact hypothesis suggests that a large meteorite struck the Earth.  The impact of the collision created enough dust to block out the sun's rays for many years.  No sun meant that plants died causing dinosaurs to starve to death. Scientists have found traces of iridium within the Earth's crust.  The concentration of iridium is much greater in meteorites compared to Earth's rocks.  Another hypothesis for the extinction of dinosaurs is volcanic activity. The movement of tectonic plates may have led to the drastic change in the climate and environment.

 

 

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