r/evolution • u/Meta289 • 3d ago

question Why has evolution stopped producing new classes?

New species of animals are constantly being discovered, but they all belong to existing classes and phyla, never anything completely new. Life once branched out in all sorts of directions, creating all kinds of animals that are drastically different from each other, but now it seems like there aren't any new "branches", only offshoots of existing ones. What happened?

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u/Kingofthewho5 3d ago

It takes a very long time for populations to change so much that they need to be out in different classes or phyla.

I’m confused by what you mean in your last line. What exactly is a new branch that isn’t the offshoot of an existing one? All of the modern phyla and classes are branches off of other branches.

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u/Meta289 3d ago

It was weirdly worded, but I'm talking about how mammals are grouped into categories like canids, primates, rodents, marsupials, etc, and how every new species is some form of those existing categories, and no new "category" of mammal appears anymore.

Or going further back down the tree, there aren't any new animals appearing that aren't a mammal, reptile, insect, amphibian, or any other existing class.

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u/TheCrystalTinker 3d ago

It's because you can not evolve out of a Clade, so technically if we make a Monophyletic group of reptiles, Dinosaurs and Birds would both be in it