They’re called dinosaurs.
What evidence do you have that “dinosaurs” weren’t evolutionarily viable?
What made them “impossible creatures?” Was there a dinosaur with a brick for wings, instead of an airfoil? Amazing that “evolution” could accidentally get the laws of aerodynamics correct. Wonder where all the fossils are from animals that had shapes that weren’t airworthy? Must have been literally billions of them before it “accidentally” got it right.
Was there a dinosaur who eschewed traditional bony armor (which is itself quite a concept...how did “evolution” discover that armor was...well...armor?) in favor of bacon? How about the dinosaur evolution evolved into an efficient breeder/feeder that used its own testicles for baiting other carnivores(the females went hungry)?
Your same evolutionist scientists claim the dinosaurs died out to a major catastrophic event...as you well know. Now they’re claiming that dinosaurs became birds. So even your cult leaders don’t claim that dinosaurs weren’t viable.
In other words, you don’t know jack s**t. But you have seen a little on TV.
How about the intermediate species. The ones with the half formed wings or fins? Or, *snicker* eighteen wings?
Explain the Cambrian Explosion, where there is the sudden appearance of fully formed fossils. Where are the fossils of the creatures that led up to them?