Source: sciencekids.co.nz, amnh.org, activewild.com
THE DINOSAURS APPEARS
Spinosaurus was among the largest of all known carnivorous dinosaurs, nearly as large as or even larger than Tyrannosaurus, Giganotosaurus and Carcharodontosaurus.
Two species are currently recognized, although others have been assigned in the past.
Velociraptor (commonly shortened to "raptor") is one of the dinosaur genera most familiar to the general public due to its prominent role in the Jurassic Park motion picture series. In real life, however, Velociraptor was roughly the size of a turkey, considerably smaller than the approximately 2 m tall and 80 kg reptiles seen in the films.
Three skeletons were discovered in northern Arizona in 1940, and the two best preserved were collected in 1942. At about 7 meters in length, with a weight of about 400 kilograms, Dilophosaurus was one of the earliest large predatory dinosaurs, though it was smaller than some later theropods. It was slender and lightly built, and the skull was proportionally large, but delicate.
While many species have been classified in the genus Iguanodon, dating from the late Jurassic Period to the early Cretaceous Period of Asia, Europe, and North America, research in the first decade of the 21st century suggests that there is only one well-substantiated species.
THE TRIASSIC, JURASSIC & CRETCEOUS PERIODS
Dinosaurs lived in the Mesozoic Era, which is also known as the ‘Age of Reptiles’. The Mesozoic Era began around 252 million years ago, and ended around 66 million years ago. It is subdivided into three smaller periods: the Triassic, Jurassic and Cretaceous periods. The earliest dinosaurs began to appear between around 231 and 243 million years ago, during the Triassic period. They were small, and walked on two legs.
Around 201.3 million years ago, a worldwide extinction event took place. This marked the end of the Triassic period and the beginning of the Jurassic period. Dinosaurs became the dominant land vertebrates (animals with backbones) after the Triassic–Jurassic extinction event. They remained so throughout the Jurassic and Cretaceous periods. Their reign came to an end with another extinction event – the Cretaceous–Paleogene extinction event – which occurred around 66 million years ago. This caused all of the non-avian dinosaurs to become extinct.