Comment: 15:13 - 16:47 (01:34)
Source: Annenberg/CPB Resources - Earth Revealed - 11. Evolution Through Time
Keywords: dinosaur, fossil, track, climate, Mesozoic, predation, environment, extinction, volcano, atmosphere, asteroid
Our transcription: But recent data, together with a better understanding of biology, have prompted scientists to rethink this view.
Fossil tracks indicate many of these creatures must have been swift footed.
Dinosaur fossils have also been discovered in places that were dry and had cool climates during the Mesozoic.
This and other evidence suggests these animals were warm blooded.
Predatory dinosaurs apparently required large amounts of food for survival, suggesting the high rate of metabolism typical of warm blooded animals.
Finally, far from living solitary lives, some dinosaurs lived in nest building herds, caring for their young.
The dinosaurs might still dominate our world today even more diverse and spectacular than ever before, but for another drastic environmental change 65 million years ago, which triggered yet another round of worldwide mass extinctions.
Geologic clues suggest several natural phenomenon may have been responsible for the change.
Dust from extremely intense volcanic eruptions possibly cooled the atmosphere enough to change Earth's climate and seriously disrupt the food chain.
Or a large asteroid may have struck the Earth cooling it as smoke and dust blocked out sunlight.
Whatever the cause, many species were no longer well suited for their environments.
Geology School Keywords