More Facts about Shark

Evolution of Shark
Sharks have existed for over 350 million years. They evolved over 100 million years before the dinosaurs did. This was long before people evolved. Most fossil evidence of early sharks is from fossilized teeth and a few skin impressions. Cladodonts, primitive sharks, had double-pointed teeth, were up to 3 feet (1 m) long fish-eaters and lived about 400 million years ago (mya).

MIGRATION OF SHARKS
There are three different types of sharks when it come to migratory patterns:

• Local sharks - these sharks do not migrate, and range only about a hundred miles from their habitat. Examples include the bonnethead shark, and the nurse shark.
• Coastal pelagic sharks - these sharks can migrate over 1,000 miles (1,600 km). Examples include the dusky shark, the blacktip sharks, the tiger shark, and the sandbar shark.
• Highly pelagic sharks - these sharks migrate across oceans. Examples include the blue shark and the mako.

Extinct Shark
Megalodon ( Carcharodon megalodon ) was an ancient meat-eating shark, living between 25-1.6 million years ago; it is extinct. It was over 40 feet (12 m) long, but this is only an estimate from fossil teeth that have been found. Its teeth resemble those of the great white shark but are almost 3 times larger; these teeth are each the size of a person's hand!


Endangered and Protected Shark
The largest sharks are decreasing in numbers around the world because of being hunted by people. The Great white shark, the Basking shark and the Whale shark are all waning. The Great white is protected along the coast of California and South Africa. Shark fossils are rare because sharks have no bones, only cartilage, which does not fossilize well. Fossilized shark teeth are very hard and fossilize well.