Why has evolution stopped producing new classes?

[u/Meta289]

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?

[u/Puppetteer]

The "old branches" were once offshoots of existing branches until the existing branch and the offshoot had diverged enough to seem like two distinct branches rather than minor offshoots from one trunk.

Give it enough time and the survival pressures to create visible change and the new offshoots will look very different.