Dinosaur (Greek for "terrible lizard") is the name given to various kinds of large extinct reptiles of the Mesozoic Era (from 230 to 65 million years ago), the interval during which they were the dominant land animals on Earth. The term was proposed as a formal zoologic name in 1842 by the British anatomist Sir Richard Owen, in reference to large fossil bones unearthed in southern England, but it is used today only in an informal sense. The various kinds of dinosaurs are classified in two formal categories, the orders Saurischia and Ornithischia, within the reptilian subclass Archosauria.
Different types of dinosaurs varied greatly in form and size, and they were adapted for diverse habitats. Their means of survival can only be inferred from their fossil remains, and some inferences are in dispute. They ranged in weight from 2 to 3 kg (4 to 6 lb), in the case of COMPSOGNATHUS, and up to 73 metric tons (160,000 lb), in the case of BRACHIOSAURUS. Most dinosaurs were large, weighing more than 500 kg (1,100 lb), and few weighed less than 45 kg (100 lb). Most were herbivores, but some saurischians (the theropods, for example) were carnivorous. The majority were four-footed but some ornithischians (the ornithopods, for example) and all carnivores strode on their hind legs.
Always classified as reptiles, dinosaurs have traditionally been assumed to have been reptilian in their physiology, cold-blooded, and ectothermic (dependent on external heat sources). In recent years several different lines of evidence have been interpreted as indicating that dinosaurs may have had warm blood and high rates of metabolism, comparable to birds and mammals. Evidence supporting this view includes upright posture and carriage; mammallike microscopic structure of bones; skeletal features suggestive of high activity; and specialized food-processing dentitions and low ratios of dinosaurian predators to prey animals, both suggesting high food requirements. The evidence is not conclusive--all the facts can be alternatively explained--but some dinosaurs may have been endothermic (maintaining body temperature and heat production by internal metabolic processes).
The reproductive means of most dinosaurs is as yet unknown. Fossil eggs, attributed to one of the horned dinosaurs (PROTOCERATOPS) and a sauropod (Hypselosaurus), have been discovered in Mongolia and France. Fragments that are presumed to be of dinosaur eggs have also been found in Brazil, Portugal, Tanzania, and the U.S. states Colorado, Montana, and Utah. In Montana, Utah, Alberta (Canada), and the Gobi Desert fossils of unhatched dinosaur eggs have been discovered. This evidence indicates egg-laying (oviparous) reproduction in dinosaurs, like most modern reptiles. A few scientists believe that some dinosaurs may have given birth to living young, but no conclusive evidence has yet been found.
Text compiled by Mr. John H. Ostrom ( Source: Grolier Encyclopedia)
In Gujarat Stegosaurus, Megallosarus, Iguanadon, Triceratops, Brontosarus, were few species of dinosaurs that roamed from place to place during Cretaceous and Jurassic periods. Fossil of new species of a dinosaur is found from Naramada River basin called Rajasaurs Narmadensis. World's one of the huge hatcheries is found just 80 km from Ahmedabad that houses fossils of various species of Dinosuras. In Kutchchh/ Kutch three species of dinosaur fossils are found.
Kutchchh/Kutch is fascinating place for paleontologists , amature reserchers and dino enthusiasts.
We organise tailormade field visits.