In 1842, an english dinosaur expert, Richard Owen, first used the term "Dinosaur", which is from the Greek language, and means 'terrible dinosaur'.
It is widely accepted that dinosaurs lived on Earth until about 65 million BC, at which point they were made extinct by a huge global cataclysm.
This catastrophy may have been a huge asteroid strike, maybe a massive increase in the world's volcanic activity, or maybe even huge floods.
An asteroid or volcanic activity may have caused sunlight to be blocked, due to the amounts of dust and particulate in the sky and this would have changed the planets ecology. Plants may have died, causing a loss in herbivorous dinosaur's food, and falling numbers of herbivorous dinosaurs would have resulted in a smaller food supply for the carnivorous varieties of dinosaur.
The first ever dinosaur to be named was "Megalosaurus" Named in 1824 by Rev. William Buckland, Megalosaurus, again from the greek llanguage means "Great Lizard" and was approximately 9 metres in length.
Seismosaurus - 40m (As long as 5 double decker buses)
Brachiosuraus - 80 tons (Same as 17 african elephants). Was 16m tall and 26m long.
Lesothaurus - about the size of a chicken.
Longest named Dinosaur:
Micropachycephalosaurus - which means "tiny thick headed lizard".
Utahraptor - was a very powerful, agile and intelligent predator.
Largest flying dinosaur:
Quetzalcoatlus - named after the mesoamerican go Quetzalcoatl, whose name means "feathered serpent".
Wingspan of up to 13m and possibly the largest flying creature of all time, though probably only weighed about 100kg.
Most intelligent dinosaur:
Troodon - not a massive dinosaur, only about 2m in length, but had a brain of similar size to to that of mammals todayt, stereoscopic vision and grasping hands
Least intelligent dinosaur:
Stegosaurus - this dinosaur had a brain of similar size to a walnut - about 3cm long.
Dinosaur fossils have been discovered for thousands of years, but were initially thought to have been the bones of mythical creatures such as dragons or giants.
It's only a very small number of deceased animals which become fossils, so evidence of the smallest and largest known dinosaurs will likely never be found.