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The definition of dinosaurs


The word ‘dinosaur’ was first publicized by English paleontologist Richard Owen in 1842. The word ‘Dinosauria’ used at that time was a combination of ‘deinos’, which meant dreadful in Greek, and ‘saura’, which meant lizard. With a wild guess the word ‘dreadful lizard’ could bring up images of sharp toes or teeth but in fact the reason Owen called them ‘dreadful lizard’ was simply because of their size. Owen’s concept was based on usage of ‘Saurian Reptiles’, which was grouped under suborder according to the original science of classification. However at present it is not used as a science of classification but only as a regular concept.

Dinosaurs first appeared on earth approximately 2 hundred million 30 million years ago and occupied the earth for 1 hundred million 60 million years. This is to say, dinosaurs first appeared in the Triassic period of the Mesozoic Era and until the end of the Cretaceus period were the reptilian which dominated the earth. Due to this the pterosauria, ichthyosauraursm plesiotaurs and such which could have been considered cousins did not belong in the dinosaur category. Academically strictly speaking, dinosaurs were reptilian which lived on the land and refers to the reptilian group which includes the saurischia and ornithischia. The saurischia had a pelvis which resembled the lizard, hence the applying of the name, and had consistent angles for the ischium, pubis and ilium. The sauropodomorpha and theropoda had such pelvises. On the other hand the ornithischia had a pelvis which resembled a bird and hence was given its name. The ischium and pubis were facing in the same direction and were close to the ilium. Here the thyreophora which includes the stegosauria type and ankylosauria type and the marginocephalia which includes the ceratopsia type and pachycephalosaurus type and ornithopoda is also included. If it were taken into account that the bird evolved from the saurischia’s theropoda, coelurosauria, then the name ornithischia can in fact be called ironical.