Dinosaurs are a group of reptiles that first appeared about 245 million years ago during the Mesozoic Era, and became extinct 65 million years ago. They were the largest land animals of their time, and some reached heights of over 30 feet (9 meters). Dinosaurs are divided into two groups: the Saurischia, which include the carnivorous dinosaurs, and the Ornithischia, which include the herbivorous dinosaurs.
The study of dinosaurs is called paleontology. It is a branch of biology that helps us to understand life in past geological periods by studying fossils. A fossil is any evidence of past life that has been preserved in rock or sediment. Scientists learn about dinosaurs by studying their bones, teeth, footprints, and other remains. Sometimes they find complete skeletons!
Dinosaur bones are found on every continent on Earth except Antarctica. The first dinosaur bone was discovered in 1677 by Robert Plot, a naturalist from England who found it in Oxfordshire. Since then, many more have been found! The largest dinosaur skeleton ever discovered belongs to a Patagonian species called Argentinosaurus huinculensis; it measures 122 feet (37 meters) long from nose to tail!
The word “dinosaur” comes from the Greek words deinos (δεινός), meaning “terrible” or “fearfully great,” and sauros (σαῦρος), meaning “lizard” or “reptile.” The term was coined in 1841 by Sir Richard Owen, a British anatomist who recognized that these creatures were distinct from both living reptiles and ancient mammals.
Interestingly enough, Owens also coined the term “dinosauria” to refer to this group of animals as well as related extinct reptiles such as pterosaurs and plesiosaurs. This name is still used today when referring to all these prehistoric creatures collectively!