Dinosaurs are a diverse group of gigantic animals of the clade Dinosauria. They first appeared during the Triassic period, 231.4 million years ago, and were the dominant terrestrial vertebrates for 135 million years, from the beginning of the Jurassic (about 201 million years ago) until the end of the Cretaceous (66 million years ago), when the Cretaceous–Paleogene extinction event led to the extinction of most dinosaur groups at the close of the Mesozoic Era.
The fossil record indicates that birds evolved from theropod dinosaurs during the Jurassic Period and, consequently, they are considered a subgroup of dinosaurs by many paleontologists. A person who studies dinosaurs is known as a paleontologist.
Fast Facts about Dinosaurs
1. The word dinosaur comes from the Greek language and means ‘terrible lizard’. The word was coined by English paleontologist Richard Owen in 1842 and was meant to refer to Dinosaurs impressive size rather than their scary appearance.
2. The time period from 250 million years ago until around 65 million years ago is known as the Mesozoic Era. It is often referred to as the Age of the Dinosaurs because most dinosaurs developed and became extinct during this time.
3. The longest dinosaur was Seismosaurus, which measured over 40 metres, as long as five double-decker buses. It was related to diplodocus, which for a long time held the honour.
4. The heaviest dinosaur was Brachiosaurus at 80 tonnes. It was the equivalent to 17 African Elephants. Brachiosaurus was 16m tall and 26m long and is the largest dinosaur skeleton to be mounted in a museum.
5. The smallest fully-grown fossil dinosaur is the little bird-hipped plant-eater like lesothosaurus, which was only the size of a chicken. Smaller fossilised examples have been found, but these are of baby dinosaurs.
6. One of the most intelligent dinosaurs was Troodon. It was a hunting dinosaur, about 2 metres long, and had a brain size similar to that of a mammal or bird of today, stereoscopic vision, and grasping hands. The speediest dinosaurs were the ostrich mimic ornithomimids, such as Dromiceiomimus, which could probably run at speeds of up to 60 kilometres per hour.
7. Dinosaur eggs come in all shapes and sizes. They tend to be ovoid or spherical in shape and up to 30cm in length – about the size of a rugby ball. The smallest dinosaur egg so far found is only 3cm long. Once the egg has been fossilised it will become hard like rock, but it will retain a structure of its own.
8. At present over 700 different species of dinosaurs have been identified and named. However palaeontologists believe that there are many more new and different dinosaur species still to be discovered.
9. Tyrannosaurus rex looked the most ferocious of all the dinosaurs, but in terms of overall cunning, determination and its array of vicious weapons it was Utahraptor that was probably the fiercest of all. Utahraptor measured about 7 metres, and was a very powerful, agile and intelligent predator.
10. It is believed that dinosaur extinction was part of a mass extinction brought about by two massive destructive events. The first of these was the collision with the Earth of a meteorite landing in what is now the Yucatan Peninsula, of Mexico. This was followed by an enormous volcanic eruption which split what is now India in half.
Why did Dinosaurs Look So Weird? Dinosaurs were around for millions of years. During that time they changed to suit their environment and conditions. Horns, plates, thorns, spines, long necks, claws, each of these served a purpose for that dinosaur. If you think about it, dinosaurs were around for a little more than 200 million years.
Human beings have been around for only about 120,000. Think how weird WE might look in another million years or so – Can’t imagine!
