Dinosaur communities were separated by both time and geography. The 'age of dinosaurs' (the Mesozoic Era) included three consecutive geologic time periods (the Triassic, Jurassic, and Cretaceous Periods).
No! After the dinosaurs died out, nearly 65 million years passed before people appeared on Earth. However, small mammals (including shrew-sized primates) were alive at the time of the dinosaurs.
Dinosaurs generally are named after a characteristic body feature, after the place where they were found, or after a person involved in the discovery.
Approximately 700 species have been named. However, a recent scientific review suggests that only about half of these are based on fairly complete specimens that can be shown to be unique and separate species.
Scientists have conflicting opinions on this subject. Some paleontologists think that all dinosaurs were 'warm-blooded' in the same sense that modern birds and mammals are: that is, they had rapid metabolic rates.
Sedimentary rocks are formed from pre-existing rocks or pieces of once-living organisms. They form from deposits that accumulate on the Earth's surface. Sedimentary rocks often have distinctive layering or bedding.
It is the period of time extending from the formation of the earth to the present. For more information visit our Geologic Time Scale Web page.
The largest complete dinosaur we know of was Brachiosaurus ('arm lizard'); it reached 23 m in length and 12 m in height (about the length of two large school buses and the height of a four-story building).
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