The Age of Reptiles

The Mesozoic Era is called the Age of Reptiles. But that only tells a small part of the story. Just like the Paleozoic Era, the Mesozoic is divided into periods. Each period has specific land forms and climates, so each period has special animals and plants that developed. The Mesozoic Era is divided into three periods: the Triassic Period, the Jurassic Period, and the Cretaceous Period.

Many species that survived the Permian Extinction died out during the early part of the Triassic Period. Trilobites, bryozoans, and rugose (horn) corals all disappeared. But many new species developed. The ammonites and brachiopods survived and began to recover. One type of ammonite was especially plentiful during the Triassic Period, the ceratitic ammonite. These ammonites are identified by the suture patterns on their shells. The suture lines are lines between the sections of the ammonite. Ceratitic ammonites had suture lines that formed a wavy pattern. There were many ceratitic ammonites in the Triassic seas.

Reptiles Are Adapted To The Hot Dry Climate

The most important development was happening to the reptiles. These animals would dominate the land, sea and air throughout the Mesozoic Era. During the early part of the Triassic Period, when Pangea was still one huge super continent, the reptiles were more adaptable to the hot dry lands.

Dinosaurs

The cold-blooded reptiles seemed to live better in the desert-like land environment than the Therapsids, or mammal-like reptiles. Many different species of the cold-blooded reptiles developed in the Triassic Period. Also, the first dinosaurs were evolving. The dinosaurs were different than the reptiles.

First, they were warm-blooded. This means the temperature of their blood was kept constant inside their body instead of changing with the outside temperature.

Second, their bone structure was different in the hips, legs and hands.

Most dinosaur species lived after the Triassic Period. They would come to dominate the Jurassic and Cretaceous periods.

Mammals First Appearance

Another land animal developing around the same time as the dinosaurs were the mammals. These mammals were very small. They weren't very important until millions of years later in the Cenozoic Era.

Reptiles In the Triassic Seas

There were many reptiles living in the Triassic seas. Ichthyosaurs developed in the Triassic period. They had a fish-like body so would have spent their life in the seas. But, they breathed with lungs and did not have gills. The plesiosaurs also developed during the Triassic. Like the ichthyosaurs, they would grow in numbers through the Jurassic and Cretaceous periods.

Reptiles Take To The Air

The end of the Triassic period saw flying reptiles develop. These animals were called pterosaurs. Most of the species of this group became important in the Jurassic and Cretaceous periods. The flying reptiles were not relatives of birds. In fact, dinosaurs are more closely related to modern birds.

Conifers and Ginkgos Replace Ferns and Lycopods

During the late Permian Period, or Pennsylvanian Epoch, the coal swamp plants were the most important. These tree-ferns and lycopods could not live in the dry climate of the Triassic Period.

Instead, the conifers and ginkgos survived the Permian extinction and developed during the Triassic. The evergreen plants were much more able to cope with the dry climates.

The Close of The Triassic Period

Many important species of both plants and animals got their start during the Triassic Period. The dinosaurs, reptiles, conifers, and ginkos would soon dominate the Jurassic and Cretaceous Periods.