Triassic Period: The Age of Dinosaurs

Sandwiched between the world’s largest known extinction event and the animal-rich Jurassic, the Triassic period marked a phase of transition and recovery. Spanning from 251 to 200 million years ago, the Triassic was the first part of Mesozoic, which means the "age of middle life." This time is also often referred to as the "age of dinosaurs," since dinosaurs were the most notable, successful and diverse creatures to emerge during the Triassic.

Triassic Geology and Climate

The supercontinent Pangea, comprising all of today’s continents fused together, slowly began to drift northward during the Triassic. In the Middle Triassic, the gargantuan landmass showed signs of breakage. Cracks developed in what is now North America, northwest Africa, west and central Europe. These rifts were the first indications that the supercontinent would later split apart into separate, smaller continents.

Fossils and geological studies indicate that the climate was mild, warm or scorching hot, depending on the location. North America, which then rested near the equator, experienced subtropical conditions from Wyoming to New England. Gingkoes, cone-bearing trees and other evergreen plant species flourished in such milder weather regions.

Mammals, Marine Life and Archosaurs

Although reptiles ruled the Triassic, this period also saw the emergence of the world’s first true mammals. While scientists continue to debate which mammals appeared first, weasel-like creatures, such as Morganucodon watsoni or Gondwanadon tapani, are likely candidates. It’s believed these first mammals were small, nocturnal insect eaters. They were also warm-blooded and furry.

The oceans were full of bizarre-looking creatures like Nanchangosaurus, with its snapping jaws and eel-like tail. Ichthyosaurs, which looked like dolphins on steroids, as well as large, round Shonisaurus, also lived in Triassic waters. At about the same time, several dinosaur-like creatures emerged. Herrerasaurus, for example, was a direct archosaur ancestor to dinosaurs. It possessed clawed, three-fingered hands and sturdy hind legs that allowed it to chase down prey. Its textured skin functioned like military fatigues, helping to camouflage the carnivore as it hid in vegetation, waiting to pounce on victims.

Triassic Dinosaurs

Dinosaurs diverged from archosaurs and came into their own around 230 million years ago. Eoraptor was one of the earliest known dinosaurs. It was only about 40 inches long, but this carnivore was built for speed and stealthy hunting. Its hand claws could tear apart prey, while its muscular hind legs allowed it to sprint towards victims. Another early dinosaur was Pisanosaurus. This plant eater could also walk on its hind legs, but it used its hands to gather ferns and other edible greenery. At up to 39 feet in length, Euskelosaurus was one of the largest early dinosaurs. The long-necked creature also consumed plant material, but it could walk on all fours or use its tail like a tripod stand, allowing it to rear up on its back legs to reach tall foliage.