Discovery Channel Video Clips
This activity contains 6 questions.
Most scientists support the hypothesis that the Cretaceous mass extinction was caused by _____.
the expansion of the continental glaciers
the impact of a large meteor
a rising sea level
Why were the scientists in the video studying fossil leaves?
Fossil plants are good indicators of animal-rich fossil beds.
Fossil leaves are what the dinosaurs ate.
Plant anatomy is a good indicator of the climate.
The surface area of the leaf correlates with competition.
What evidence do scientists use to support the meteorite impact hypothesis?
Sea level rose at the same time.
Numerous meteorite impacts have been correlated to changes in the environment.
A global layer of iridium has been dated to about the same time as the mass extinction.
Cold-tolerant dinosaurs did not go extinct at a date correlated with the impact.
Why do scientists think that the iridium layer is evidence of meteorite impact?
Iridium is rare on earth and common in meteorites.
The iridium layer was released into sediments by decaying dinosaur bodies.
The plants living then were killed by iridium poisoning.
Iridium quickly evaporates from volcanic lava.
Scientists believe that a meteorite struck _____, leading to the extinction of dinosaurs.
How long ago did the dinosaurs go extinct?
12 million years
65 million years
300 million years
3.7 billion years
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