Ancient Sharks and Crocodiles’ Nemesis: Man
Since ancient times, people have feared sharks and crocodiles. But how long have these two species actually been on earth and how did they evolve? Crocodiles and sharks have one thing in common: the fact that they have remained completely unchanged for hundreds of millions of years of evolution. It is true, roughly speaking, that if a modern human being could have taken a swim in a river or in the open ocean, 150 million years ago, he would immediately have recognized that animal as a crocodile or as a shark, but there are many substantial differences in their habitat, diet, morphology, size and weight among the various genera which have marked the evolutionary history of these creatures.
Carcharocles megalodon collection from the Gatun Formation (CC BY-SA 2.5)
Sharks Oldest Creatures On The Planet
Sharks are considered among the oldest creatures that have ever lived on this planet. The fossil remains of these animals are about three times older than those of dinosaurs, and almost a hundred times more archaic than the entire evolutionary path followed by the genus Homo itself. The family tree of the Chondrichthyes stands proudly in the long path of natural history for a time span of about 400 million years. Primitive forms of sharks swam sinuously in rivers and early oceans, even before the insects took flight and even long before the plants had actually colonized all the continents.
