this post was submitted on 08 Nov 2023
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Just because they didn't change their appearance doesnt mean they did not evolve. It is somewhat misleading to say that, but conveys a point I guess.
More relevantly, the fossil records for sharks are mostly their teeth and jaws, because all their other bones are cartilage and rarely fossilize.
"Sharks haven't significantly evolved in appearance in 350 million years" is therefore based on reconstructions made under the assumption that the old sharks mostly looked like current sharks, which may or may not be true.
Though we can get a surprising amount of information that way, for example one change is that their jaws used be more at the end of their snout instead of more underslung like today, like so:
https://www.smithsonianmag.com/science-nature/new-technologies-reveal-strange-jaws-prehistoric-sharks-180977396
You'll note the Goblin Shark still has hints of that design.
I made sure to say barely instead of not at all, but you're right, there was certainly some evolution happening
Yeah, thankfully Megalodon isn't cruising around anymore. Though that might have delayed European expansion until they had metal clad vessels....
That sounds like a fun story, like a Pride and Prejudice and Zombies but instead it's Master and Commander and Megalodon.
Can we even know for sure that Carcharocles Megalodon is in fact excinct?
You can't prove the non existence, but you can be very sure about some things. Megalodon lived near the surface, because it liked warm water(AFAIK), so it's likely that if it wouldn't be extinct there's a high chance that we would notice it, since Megalodon was kinda big.
Yeah okay, seems plausible then. It's more fun to believe otherwise though, not gonna lie. After all, there's still so much we don't know about our oceans.
I just saw one the other day at the 7-11