first: evolution doesnt predict nested hierarchy either
It does.
(convergent evolution for example)
Convergent evolution also falls into nested hierarchies.
Take sight, for example. That's a traight that evolved a couple dozen times independently.
The eyes of humans do NOT fall into a nested hierarchy with the eyes of insects.
On the branch of humans though, all creatures have the same type of eyes. We all share a blind spot, for example.
. as for the second claim (we should NOT see species with a mixture of bird and mammal features) i can say the same thing: if we will find a species that is a mix of a bird and a mammal features it will "solve" by convergent evolution
Nope, for the reason explained above.
Both a bat and a bird has wings, but they do NOT fall into a nested hierarchy. These are independent developments. Only developments coming from the same ancestry will fall into a nested hierarchy. That's kind of the whole point of a nested hierarchy.......................
There is no reason why we would expect a designer to give vertebrates a blind spot in their eyes, while an octopus doesn't have that problem.
In evolutionary context, this however makes perfect sense.
for example: if we will find a cat with wings we can claim that wings evolved twice (in borth birds and mammals).
No need to go to imaginary cats with wings.
We HAVE a mammal with wings. It's called a bat.
We also have mammals that live in the sea and look like fish to the uneducated eye, like whales and dolphins. They don't have gills though... they have lungs.
And they don't swim by horizontal body movement like actual fish or like the motion a crockodile's body makes while walking... Nope, it swings by moving its body in vertical fashion. Up and down. Just like land-walking mammals do.
It's a spine thingy.
Nested hierarchies. It works.