How long have sharks been in existence?

Geological records show that modern shark species have existed for between 201 million and 174 million years. Earlier fish species similar to sharks existed as early as between 419 million and 359 million years ago.

The 13 to 22 shark families that currently exist first appeared during the Cretaceous Period, around 66 million to 145 million years ago. Around 400 species of sharks still exist, but some are threatened because human fishing activity has depleted their populations. The shark's body shape has not evolved to a great extent; the primary changes in sharks include evolved enhancements to their mechanisms for feeding and swimming.