Adapted from Dinosaurs: The Very Latest Information and Hands-On Activities From the Museum of the Rockies, by Liza Charlesworth and Bonnie Sachatello-Sawyer. A Scholastic Professional Book.

Way back in 1676, Robert Plot, the curator of an English museum, described and drew a thigh bone that he believed belonged to a giant man. Although that fossil disappeared without a trace, the surviving illustration suggests that it may well have been part of a "Megalosaurus." Later, in 1822, large teeth discovered in England by Mary Ann Mantell and her husband, Gideon, were thought to be the remains of a huge and extinct iguana. It wasn't until 1841 that British scientist Richard Owen came to realize that such fossils were distinct from the teeth or bones of any living creature. The ancient animals were so different, in fact, that they deserved their own name. So Owen dubbed the group "Dinosauria," which means "terrible lizards."

Across the ocean in North America, dinosaur tracks were studied in the Connecticut Valley, beginning in the 1830's. They were believed to belong to enormous ravens, freed from Noah's Ark after the Great Flood. At that time, paleontology was long on deduction and short on evidence. This was remedied when two wealthy and competitive American scientists, Othniel Marsh and Edward Cope, raced to excavate fossils in the Rocky Mountain region. In the late 1800's, their separate teams, armed against Native Americans and each other, dug up tons of bones from several sites. All in all, Marsh and Cope's rivalry — known as the Bone Wars — uncovered 136 new species. And their respective fossil displays generated excitement for dinosaurs the world over.

In the 1900's, enthusiasm for dinosaurs grew steadily, attracting the attention of the scientific community. Institutions such as the Carnegie Museum of Natural History and the American Museum of Natural History assembled dig teams, which uncovered many rich bone beds in North America (as did their counterparts overseas). New sites in Utah revealed several different species, including "Camarasaurus," "Apatosaurus," and "Stegosaurus;" "Tyrannosaurus rex" remains were found in Montana and baby Coelosaurs in New Mexico.

In recent decades, dinosaur research continues, but the emphasis has shifted from finding and classifying these animals to analyzing and reconstructing their lives and habitats. In the late 1960's, Robert Bakker proposed that these ancient creatures may well have been as agile and energetic as warm-blooded animals. In the mid 1970's, Peter Dodson, along with James Farlow, hypothesized that they used their horns to attract the attention of females, as well as for fighting. And in the late 1970's, Jack Horner made history by identifying some of the first dinosaurs nests and eggs in North America. These important "Maiasaura" fossils helped to determine that some species nested in colonies and cared for their young.

In the past few years, several paleontologists, including Ken Carpenter, Phil Currie, and William Coombs, have identified juvenile dinosaurs that were previously thought to be adults; and David Weishampel has theorized that some dinosaurs probably used their crests and nasal passages to create sound. Each day, scientists working all over the world, in the field and in research labs, help to redefine the meaning of the world "dinosaur."