Furthermore, we dont even see crossovers between the 5 Phylla (classes of animals) anywhere, at any time.
Try different kingdoms.
They're called sponges:
They are animals. They have little in the way of tissues and no true organs. They have lots of specialized cells which act like, and bear a strong resemblance to, a choanoflagellate:
and an amoeba:
..among other cell types, which also look a lot like free-living protozoans.
In fact, they can live on their own, but they'll eventually grow a whole new sponge.
They straddle the place where Kingdom Protozoa and Kingdom Animalia kiss.
Where are the giant mammaried mosquitos?
They never needed them. Their system of reproduction does a dandy job without tits.
Where are the snakes which deliver live young?
Ovoviviparity. Let me show you it.
I havent seen too many feathered fish around lately!
Why would they need feathers? They've got scales and they don't need the insulation. Besides, feathers would add drag and make it hard for most of them to swim.
But, if you want something that vaguely looks like feathers...there's this one. They're not exactly feathers, per se. But this species of fish has colorful poison quills.
In fact, most of his cousins have quills, spines and poison needles.
This one walks.
So does this one.
The climbing perch (below) hunts on land. It and all of its relatives have no problem breathing air. The climbing perch is routinely kept in wheelbarrows at the market and squirted occasionally with water to keep its gills moist. Sometimes, it even climbs small trees or shrubbery.
This one flies. But it doesn't need feathers to do it.
So there you have it. Several fish that walk, some that fly, some that have venemous quills that manage to look a lot like feathers, some animals that blend traits from two broad groups of living organisms, and snakes (among others I didn't bother to list) that give birth to live young. I'll have to take a mulligan on your Dolly Parton mosquitos, and there aren't fish with true feathers, but hey. I can keep finding marginal cases like these.
But none of this matters, because you're simply constructing a strawman version of evolution that doesn't exist in the real world. So it really doesn't matter what I show.
Have fun beating on your strawman.