Shark evolution has just hit the news and here is a "shocker," it appears that sharks have continued to evolve over the last millions of years despite the popular press stressing how "primitive" they are (actually, if they had not evolved at all for the last 325 million years, that would be much more astounding).
What is interesting is that what appears to have evolved most visibly in the new study is a change in the way the gills and jaws articulate.
From Sci-News, “Sharks are traditionally thought to be one of the most primitive surviving jawed vertebrates. And most textbooks in schools today say that the internal jaw structures of modern sharks should look very similar to those in primitive shark-like fishes. But we’ve found that’s not the case. The modern shark condition is very specialized, very derived, and not primitive,” said Dr Alan Pradel, who is the lead author of the study published in the journal Nature.
Basically, if the finding holds and the ancient shark is a reasonable example of what shark ancestors looked like (and not a one-off oddity), then modern sharks have gill structures and associated jaws that are quite different and refined from the ancestral "primitive' state, allowing, among other things, more flexibility in feeding - always an important feature.
I like this quote from the Science Recorder: “The best analogy I can come up with is this: It’s like comparing a Model T Ford with a modern automobile,” said researcher John Maisey of the American Museum of Natural History in New York City in a statement. “They are both recognizably the same kind of thing. But they are completely different under the hood. We found the Model T of sharks."
You can check out more on the story at NPR -