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Life's Evolving Classifications · Acedra
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Life's Evolving Classifications
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0:02
This is not a dinosaur. But it used to be. For centuries, as we tried to make sense of the diversity of life on earth, we created animal families according to looks alone. And dinosaurs were basically anything that was big and scary and scaly and dead. But that doesn’t actually make a lot of sense. It’s a lot like, if you looked at all of humanity and assumed all the Conan O’Brien look-alikes belonged in one family, and bearded people in another, and people with bad posture
0:31
in another, and everyone with unibrows in another. Not only would you have to make ridiculous decisions along the way, like what to do with Conan O’Brien look-alikes with unibrows, but perhaps one of the people with bad posture actually has more in common with the bearded people than the rest of the bad posture family. You’d end up with families that aren’t families, and that’s why we draw our human family trees according to actual relationships, like parents and grandparents and brothers
0:55
and sisters. Evidence from fossils and DNA have shown us that all living things are linked, and that we can create animal families by finding their most recent common ancestors. So despite the fact that whales have fins, they’re more closely related to hippos than to fish. And even though sloths are long-armed and hairy and climb trees, their cousins are anteaters and armadillos. And the big, scary, scaly, dead group of animals belong to several different families.
1:21
Some – the group we now call dinosaurs – belong to a branch that includes modern-day birds; others share family ties with today’s snakes; and we can trace our own family trees back
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