Dinosaurs are a diverse group of reptiles, that first appeared
during the Triassic period, about 243 million years
ago. Through most of the 20th century, before birds were recognized
as dinosaurs, most of the scientific community believed dinosaurs to
have been sluggish and cold-blooded. Most research conducted since
the 1970s, however, has indicated that dinosaurs were very active
animals, that engaded in social interactions.
The first dinosaur fossils were recognized in the early 19th
century, with the name "dinosaur", meaning
terrible lizard – now we know that they were not lizards at
all and are closer to crocodiles and birds than they are to a common
skink.
Since then, mounted fossil dinosaur skeletons have been major
attractions at museums worldwide, and dinosaurs have become an
enduring part of popular culture. The large sizes of some dinosaurs,
as well as their seemingly monstrous and fantastic nature, have
ensured persistent public enthusiasm for those remarkable creatures.