Of course, no human being has ever seen a living dinosaur. The dinosaurs had been extinct for about 63 million years before humans appeared on Earth.

If no one has ever seen a dinosaur how do we know what they look like? Well, scientists have found their fossilized bones, sometimes they have even found complete skeletons.

By studying dinosaur bones, scientists have been able to reconstruct what they looked like, how they moved, even what they ate. Most of what we think we know about dinosaurs is the result of educated guesses based on comparing the dinosaur skeletons with modern animals.

Dinosaurs were created as an identifiable group of ancient animals by British scientist Richard Owen who, in 1842, coined the name Dinosauria meaning "terrible lizards." At the time there were three recently discovered fossil creatures to be included in the newly created group of ancient animals. These were Iguanadon, Hylaeosaurus and Megalosaurus.

Scientists today classify dinosaurs as reptiles although they were somewhat different from such modern reptiles as snakes and lizards. The closest living (living today) relatives of the dinosaurs are thought to be birds.

The first known discovery of dinosaur bones happened in 1786 when an enormous skull with jaws a meter long was found in a chalk quarry in the Netherlands.
Then, about 1810, eleven-year-old Mary Anning unearthed some unusual fossil bones in the 200-million-year-old limestone cliffs of Lyme Regis in Dorset, England. During the next twenty years or so the Anning family collected the fossils -- remains of ichthyosaurs ("fish-lizards") and pleisosaurs ("near-lizards") -- and sold them to tourists and to scientists from Cambridge and Oxford.
In 1825 a quarry near Cuckold, Sussex revealed some mysterious fossilized bones that were reconstructed by the local doctor and naturalist Gideon Mantell as Iguanadon.
In America, strange fossil footprints discovered in Massachussetts in 1802 were wrongly identified in 1836 as the three-toed prints of a huge bird. Fossil hunting in the U.S. took off in the 1870's. In the 1880's Othneil Marsh of Yale was the first to reconstruct Brontosaurus ("thunder lizard").
In 1907 the fossilized remains of an immense Brachiosaurus was found in East Africa. The first dinosaur nests and fossilized eggs were found in 1922 in Mongolia.
Evidence of dinosaurs has now been found on every continent of the world.

Dinosaurs existed for about 150 million years during three geologic periods, the Triassic, Jurassic, and Cretaceous. The first dinosaurs probably lived about 215 million years ago and the last dinosaurs probably died out about 65 million years ago.
Mammals existed at the same time as the dinosaurs but they were small primitive types and not the same mammals that we are used to seeing today. Then, during the time that dinosaurs were becoming extinct, fossil discoveries show us that more and larger mammals were around than before.
Primates, the group of mammals to which humans belong, have existed for about 60 million years. Although they are primates, humans are a young species and have existed on Earth for less than 1 million years.

Some were quite small, about the size of a chicken. Others were huge; much bigger than any animals living on land today.

The Triassic Period began about 225 million years ago when all of the major continents that we know today were joined together as one land mass that we call Pangaea. During the Triassic, Pangaea began to split apart into a northern part that included what is now North America, Europe and Asia, and a southern part that included what is now South America, Africa, Antarctica, India, Australia, and parts of southern Asia.
The world in Triassic times was cool and dry with vast deserts in the interior of Pangaea. Coniferous forests covered the high lands and, closer to sea level, were plants called cycads, large horsetails, and ferns.
The animal population included primitive amphibians and reptiles. By the late Triassic the first dinosaurs roamed the uplands and some small, primitive mammals had appeared.

The Jurassic Period followed the Triassic and lasted for 50 million years. The land that would become North America was splitting apart from what would later become Europe, with the creation of what is now the Atlantic Ocean. Similar changes were occuring in the southern hemisphere.
Dinosaurs were the dominant land animal life. The world climate was much more tropical - warm and humid. Mammals continued to evolve but were all small, rather inconspicuous animals.

The Cretaceous Period lasted for about 71 million years. During this era the great mountain ranges of the world were formed, and the continents took shape much as we know them today. Plant life became more varied during this time and scientists have found evidence of grasses, flowering plants, bees and butterflies. In the oceans fish life was increasing and on land mammals were becoming larger and more dominant. By the end of the Cretaceous the dinoaurs had disappeared and mammals were the dominant animal life forms.

[Home] [Main Index and Search]

Send feedback to

Explorit Science Center
P.O. Box 1288, Davis, CA 95617, USA

Phone: (530)756-0191     Fax: (530)756-1227

Page last updated: April 27, 2006