Shark week goes on, so lets talk about some pre-historic sharks and a discovery channel favourite -
Shark week goes on, so lets talk about some pre-historic sharks and a discovery channel favourite - Megalodon. These sharks all lived a very long time ago - the megalodon (top and bottom) between 28 and 1.5 million years ago, stetacanthus (middle left) around 360 million years ago and finally helicoprion around 280 million years ago. Despite what certain documentaries might imply, megalodon is most definetly extinct, but at its time it was the apex predator of the ocean, up to 25 meters in length, weighing in at 100 tonnes and with teeth up to 200 mm. It was probably found all over the world and fed on large whales. Less is known about the other two sharks pictured, quite a few fossils of the distinctHelicoprion tooth whirl have been found but if it had any functionality beyond what our jaws have now is unclear. It’s thought that the odd anvil shaped dorsal of stetacanthus may have been used for scaring of predators or even attaching itself to larger animals. Freaky stuff, but most definitely all very extinct. -- source link
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