Written by: Aayaan Rai - 31006, Grade VI
Posted on: 10 May, 2024
Dinosaurs were the biggest animals to ever walk the Earth. They were big, scaly, two- or four-legged prehistoric creatures. There were two types of dinosaurs in terms of hips: Ornithischians and Saurischians. Ornithischians involve only herbivore dinosaurs, and Saurischians involve carnivore dinosaurs and long-necked herbivore dinosaurs known as sauropods. One fact: Everyone may think that birds evolved from bird-hipped dinosaurs, but in reality, they evolved from lizard-hipped dinosaurs! Dinosaurs lived in an era known as the Mesozoic Era. There were three periods in that era: Triassic, Jurassic, and Cretaceous.
Triassic period: The Triassic period was the first period in the Mesozoic era. The first dinosaurs like Postosuchus, Herrerasaurus, and Eoraptor appeared in that period. The continents we know today were joined together, forming a supercontinent called Pangaea. Before the Triassic period, the animals of the Earth had been killed by an extinction event. The Triassic period saw the return of life on Earth.
Jurassic period: The Jurassic period was the second period of the Mesozoic Era. The supercontinent, Pangaea, split into two different landmasses. The ground was wetter and milder. Plant life flourished and spread in the form of conifer trees, ferns, and palm-like cycads. This period saw the appearance of giant meat-eaters and plant-eaters and marine reptiles.
Cretaceous period: The Cretaceous period was the last and the longest period of the Mesozoic Era, which lasted for 80 million years. There were more dinosaur species in the Cretaceous period than in any other period in the Mesozoic era. It ended with a mass extinction, wiping out over 75 percent of the world's animal species. Scientists divide dinosaurs into two different groups: Ornithischians and Saurischians. Saurischians mean lizard-hipped, and Ornithischians mean bird-hipped. The saurischians include theropods such as Coelophysis, Tyrannosaurus, etc., and sauropods (long-necked dinosaurs) such as Brachiosaurus, Diplodocus, etc. These big, scaly reptiles ruled the Earth for 165 million years until a huge catastrophe caused the death of all the dinosaurs. The "Age of Reptiles" ended.
