Sharks are unique and amazing in that they have outlasted all other large creatures on earth. Sharks evolved over 420 million years ago, long before the earliest dinosaurs, which appeared 230 million years ago. When sharks first appeared, there was virtually no life on land.
from wikipedia:
http://www.elasmo-research.org/educa...logic_time.htm
Although most life in the oceans died off during the mass extinction of 252 million years ago, The Great Dying, sharks survived. And when the dinosaurs were wiped out 65 million years ago, all the other large predators in the oceans became extinct, but not sharks.
Most large carnivores didn't survive for so long. For example, T-Rex (the largest land predator) was only on earth for about 1.5 million years. In the oceans, some large predatory dinosaurs survived much longer than land dinosaurs. The plesiosauria existed for 135 million years (the entire Jurassic and Cretaceous periods). However, like the land dinosaurs, they all died off 65 million years ago.
But sharks survived.
From BBC: http://www.bbc.co.uk/nature/life/Shark#p0036vd6
from wikipedia:
Evidence for the existence of sharks dates from the Ordovician period, over 450 million years ago, before land vertebrates existed and before many plants had colonized the continents. The oldest generally accepted shark scales are from about 420 million years ago, in the Silurian period.
Sharks appeared on the fossil scene about 455 to 425 million years ago. Those embodiments of prehistoric life, the dinosaurs, were relative late-comers - one of the earliest known genera (Herrerasaurus) dates back only about 230 million years.
Most large carnivores didn't survive for so long. For example, T-Rex (the largest land predator) was only on earth for about 1.5 million years. In the oceans, some large predatory dinosaurs survived much longer than land dinosaurs. The plesiosauria existed for 135 million years (the entire Jurassic and Cretaceous periods). However, like the land dinosaurs, they all died off 65 million years ago.
But sharks survived.
From BBC: http://www.bbc.co.uk/nature/life/Shark#p0036vd6
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