Southern Right Whale.
Source: Hakai Magazine.
Sometimes the solutions to the common tasks of living can be odd. Consider the ingestion and processing of food, from the four stomachs of cows to the baleen of certain species of whale.
And then there’s this shark, thankfully long extinct:
About 310 million years ago some sharks had saws for jaws – and now we know how one of those sharks, called Edestus, fed. The “saw blade” in its lower jaw glided backwards and forwards like the blade on some modern power tools, allowing the shark to cut through soft prey like fish.
We know that Edestus was a very odd shark that grew to the size of a modern great white. It had what look a lot like two saw blades in its mouth – one in the upper and one in the lower jaw. The two blades, which could each be 40 centimetres long but just 3 cm wide, seem to have locked together when the shark closed its mouth, a bit like the blades on a pair of serrated scissors. …
A careful analysis shows that it had a distinctive hinge between the lower jaw and the rest of its skull. This allowed the lower jaw – and its saw blade – to slide back and forth relative to the upper blade, which stayed fixed in place. [Leif Tapanila at Idaho State University and his colleagues] says the lower jaw worked a bit like the blade on a jigsaw power tool. “It pulled backwards during the bite. This raked the upper and lower teeth past the food, slicing and splitting it in half.” [NewScientist]
I regret to say I did not find a picture of the fossil, or an artist’s rendering, that I felt was freely available, so you’ll just have to imagine it for yourself.
And let’s not forget Helicaprion:
