Fish Updated +Created
This paraphyletic subgroup is easy to form the "acquatic only" (fishes) vs "things that come out of water" (tetrapods). Though mudfish make that distinction harder.
Which kind of makes sense, why would you want for limbs unless you are going to stay out of water!
Homeothermy Updated +Created
It is quite mind blowing that this is polyphyletic on mammals and birds, what can't parallel evolution achieve??
Figure 1. . Source. Highlights how birds should obviously be classified as reptiles.
Model organism Updated +Created