Dinosaurs are pre-historic reptiles that arose during the Middle to Late Triassic Period of theÂ Â Â Â Â Â Â Â Mesozoic Era. They were members of a subclass of reptiles called the archosaurs.The study of dinosaurs began during the 1820s, when scientists discovered the bones of a large land reptile they named a Megalosaurus buried in the English countryside.
A leading paleontologist came up with the name dinosaur in 1842, dinosaurs were larger than any reptile on earth and they walked with their legs directly beneath their bodies instead of out to the sides and had three more vertebrae in their hips than other known reptiles.
Scientists have divided the dinosaur group into two orders: the â€œbird-hippedâ€ Ornithischia and the â€œlizard-hippedâ€ Saurischia.
There are many myths that try to explain why dinosaurs went extinct, some paleontologists claim,
- The extinction was caused by a catastrophe such as a meteorite.
- Others believe that a more gradual process was responsible.
- Some theories are that competition between dinosaurs and mammals was the cause,
- A number claim climate changes caused the dinosaurs extinction.
They disagree about the amount of time it took for the extinction to take place. Some say it happened in several days. While others say it took from hundreds of generations to over half a million years
However the most scientists agree that their extinction was caused by a huge asteroid that struck the Earth about sixty five years ago they had live on earth for around one hundred and sixty million years and were more than one thousand species.
They claim that when the asteroid struck, it caused big changes on the earth it left a crater about two hundred kilometers wide in the area that is now Mexico. A huge cloud of dust filled the air, blocking out the sun’s light and warmth and causing many plants to die. Fires started near the crater, gases were released into the atmosphere, causing cooler temperatures and acid rain
By studying fossils, the scientists who did the research on dinosaur’s extinction claimed that the populations of large herbivores plant-eating dinosaurs like triceratops, duck-bills and ankylosaurushad had decreased greatly by the late Cretaceous period. This decline in food for plant eating dinosaurs caused them to die quickly.
Scientist claim that as the dinosaurs at the bottom of the food chain died and their prey, the meat eating dinosaurs also went extinct.
The reasons for dinosaur extinction continuously evolve, with scientists from different parts of the world coming up with new findings, however majority lean towards the fact that extinction was caused by a catastrophe a meteorite hitting the earth.