THE DINOSAURS ARRIVED ...
Scientists believed that the earth had existed for about 4,500 million years and to understand such a vast span of time, they divided it into periods
- TRIASSIC Period (245 - 204 MYA)
- JURASSIC Period (239 - 140 MYA)
- CRETACEOUS Period (139 - 66 MYA)
Most scientists believed dinosaur first appeared on the planet during the middle of the Triassic period. At that time the earth is made up of a huge land mass or super-continent known as PANGAEA. The super-continent then splitted into two big land masses called LAURASIA and GONDWANALAND. The continents that we know today is the effects of the futher splitting of these land masses. This drifting phenomenon is continuing to the present day at the rate, scientists estimated, 4 cm per year.
The Eoraptors and Herrerasaurus were believed to be the earliest of the dinosaur species that existed sometime in the middle of the Triassic period (about 225 MYA). These dinosaurs were carnivorous and their main diet consist of small reptiles and lizard liked creatures. Their fossilized skeletons were first discovered in Valley of the Moon, in the southern part of Argentina. The Lagosuchus, a two legged animal, was probably the most controversial creature of the Triassic period. The primitive structure of the Lagosuchus, lead scientists to believe that dinosaurs probably evolved from these species. The Lagosuchus itself is not classified as dinosaurs, it is more related to crocodiles and Pterasaurs or the flying reptiles.
One of the early large dinosaurs that appeared on earth was the Pleateosaurus. It measured 8 metre long and stood 3 metre high. The Pleateosaurus fed on leaves, plants and roots. Scientists classified Pleateosaurus as Prosaurapods. Other prosaurapods that existed in this era were Lufengosaurus, Mussaurus and Anchisaurus.
In the late Triassic period, carnivorous dinosaurs began to appear. The Saltopus, Procomsognathus and Syntarsus were among the discoveries by paleantologists. These dinosaurs were small in size but very agile. One of the tiniest dinosaur of Triassic age was the Pisannosaurus. It measured about 90 centimetre long. Some experts believed that the chicken-sized Pisanosaurus was the first ornithopod or bird hipped dinosaur. Unfortunetly, little is known about this small dinosaur. Discovery in Argentina of skeletons revealed a partial structure of what wqs thought to be a Pisanosaurus. This dinosaur lived about 210 million years ago in the late Triassic Period. Another tiny dinosaur from Triassic Period was the Saltopus. Its tiny skeleton was found at the beginning of this century at Sandstone Quarry, Scotland. This tiny dinosaur was only about the size of a cat and fed on small animals and insects. Coelophysis, was probably the largest of the carnivor of the late Triassic, a relative of the saltopus measuring about 4 metre long and stood 2 metre high was a nimble, fast moving hunter. It was also thought that Coelophysis were cannibals, killing their own species for food.
Traces of mammals were also found in the Triassic period, but most of the mammals were small, the size of a mice. Ancestor of the crocodiles, the protosucus also inhabit the earth during the Triassic period.
The planet habitat were mostly made of horsetail plants, conifers, fern and cycand. These plants flourished during the Triassic period and forms a major food source for the dinosaurs.
The dinosaurs have arrived !!!
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