species is probably the wrong word. maybe genus or phylum. apologies for the rusty biology. but sharks have been sharks for 400 to 450 million years. I'm sure

species is probably the wrong word. maybe genus or phylum. apologies for the rusty biology. but sharks have been sharks for 400 to 450 million years. I'm sure sharks are terrestrial in origin, but that's an intergalactic timescale during which very little evolutionary change occurred, or was necessary, for a particular category of creature. maybe tardigrades have been tardigrades for 450 million years too.