Prehistoric Reptiles
Dinosaurs were reptiles and most hatched from eggs. No dinosaurs could fly and none lived in the water.
Millions of years ago, long before there were any people, there were dinosaurs. Dinosaurs were one of several kinds of prehistoric reptiles that lived during the Mesozoic Era, the “Age of Reptiles.”
Varying Size
The largest dinosaurs were over 100 feet (30 m) long and up to 50 feet (15 m) tall (like Argentinosaurus, Seismosaurus, Ultrasauros, Brachiosaurus, and Supersaurus). The smallest dinosaurs, like Compsognathus, were about the size of a chicken. Most dinosaurs were in between.
Plant-eating sauropods were the largest animals to ever walk on Earth - but blue whales are more massive than any of the dinosaurs were!
Color, Behavior, and Sound
No one knows what color or patterns the dinosaurs were.
It is very difficult to figure out how the dinosaurs sounded, how they behaved, how they mated, what color they were, or even how to tell whether a fossil was of a male or a female.
Kinds of Dinosaurs
Most dinosaurs were plant-eaters (also called herbivores). For example, Triceratops was a plant-eating dinosaur.
Some dinosaurs were meat-eaters (also called carnivores). For example, T. rex was a meat-eating dinosaur.
There were many different kinds of dinosaurs that lived at different times.
- Some walked on two legs (bipedal), some walked on four (quadrupedal). Some could do both.
- Some were speedy (like Velociraptor), and some were slow and lumbering (like Ankylosaurus).
- Some were armor-plated, and some had horns, crests, spikes, or frills.
- Some had thick, bumpy skin, and some even had primitive feathers.
When Could You Find Dinosaurs?
When the dinosaurs lived, the Earth’s continents were jammed together into a supercontinent called Pangaea and the Earth was warmer than it is now.
The dinosaurs dominated the Earth for over 165 million years during the Mesozoic Era, but mysteriously went extinct 65 million years ago. Paleontologists study their fossil remains to learn about the amazing prehistoric world of dinosaurs.
Extinction
The dinosaurs went extinct 65 million years ago, probably because of the environmental changes brought about by an asteroid hitting the Earth.
The dinosaurs went extinct about 65 million years ago, at the end of the Cretaceous period, which was a time of high volcanic and tectonic activity. There are many theories why the extinction occurred. The most widely accepted theory is that an asteroid impact caused major climate changes to which the dinosaurs couldn’t adapt.
Are There Any Left?
Some dinosaurs were very bird-like and may be the ancestors of today’s birds.
Dinosaurs probably live on today as the birds. All that’s left of the dinosaurs are fossils and, perhaps, the birds. Dinosaur fossils have been found all over the world, maybe even near where you live!
Misc. Info
There are almost 500 described dinosaur genera and many more species. Every few months (sometimes weeks), new finds are unearthed.
Although dinosaurs’ fossils have been known since at least 1818, the term dinosaur (deinos means terrifying; sauros means lizard) was coined by the English anatomist Sir Richard Owen in 1842. The only three dinosaurs known at the time were Megalosaurus, Iguanodon, and Hylaeosaurus, very large dinosaurs.
The oldest known dinosaur is Eoraptor, a meat-eater from about 228 million years ago.
Dinosaur Activities
- Find It!
- A print-out for 2nd graders. Skills: reading, writing, research, and comprehension.
- Word Unscramble
- A print-out for 3rd graders. Do this writing/spelling activity after (or while) reading this page. Unscramble the words to answer questions about dinosaurs.
Dinosaur Info Sheets
Just click on an animal’s name to go to that information sheet. If the dinosaur you’re interested in isn’t here, check the Dinosaur Dictionary or the list of Dinosaur Genera.
How to write a great dinosaur report.
Names with an asterisk (*) were not dinosaurs.