What is a 'dinosaur'?

Answer 1

Dinosaurs (or the dinosauria) are a group of archosaurian reptiles (Reptilia) that first appeared about 230 million years ago, during the Triassic Period of the Mesozic era.

The word 'dinosaur' is derived from Greek, meaning 'Terrible (or Fearfully-great) Lizard'. Contary to their name, dinosaurs are not lizards. Lizards (Squamata) are a different group within Reptilia.

The dinosaurs are by many comparisons, one of the most successful reptilian, or even land inhabiting, life forms ever to walk the earth. There were two main groups, Saurischia and Ornithischia.

One of the ancestral characteristics of dinosaurs, is the ability to walk on two legs (bipedal) on birdlike hips (or rather birds have dinosaur like hips as dinosaurs arrived first!). Several of the Ornithischian groups evolved quadrupedalism.

Some of the sauropod dinosaurs had incredibly long necks, the longest of any animals to ever have existed.

Many of the type of Dinosaurs that lived in the mesozoic, are now extinct. Their demise, thought to have been brought about by a cataclysmic event in the form of a collision with a large body of rock from space, was decided approximately 65 million years ago.

However, certain types of small fuzzy theropod dinosaurs did survived to the present day. We call them Birds. So, contrary to popular belief, dinosaurs as a group are not extinct.

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1. Any of various extinct, often gigantic, carnivorous or herbivorous reptiles of the orders Saurischia and Ornithischia that were chiefly terrestrial and existed during the Mesozoic Era.
2. A relic of the past: "living dinosaurs of the world of vegetation" (John Olmsted).
3. One that is hopelessly outmoded or unwieldy: "The old, big-city teaching hospital is a dinosaur" (Peggy Breault).

It is a reptile that lived millions of years ago. People who dig up bones find old dinosaurs bones and usually put them in a museum.
Dinosaurs are a diverse group of animals of the clade Dinosauria. They first appeared during the Triassic period, approximately 230 million years ago, and were the dominant terrestrial vertebrates for 135 million years, from the beginning of the Jurassic (about 200 million years ago) until the end of the Cretaceous(65.5 million years ago), when the Cretaceous-Paleogene extinction event led to the extinction of most dinosaur groups at the close of the Mesozoic Era.

Answer 2

# Any of various extinct, often gigantic, carnivorous or herbivorous reptiles of the orders Saurischia and Ornithischia that were chiefly terrestrial and existed during the Mesozoic Era. # A relic of the past: "living dinosaurs of the world of vegetation" (John Olmsted). # One that is hopelessly outmoded or unwieldy: "The old, big-city teaching hospital is a dinosaur" (Peggy Breault). For the source and more detailed information concerning this subject, click on the related links section indicated below.