Gradual change that over time can result in a large change. Journey of 1000 miles…
Well for mammals that would be reptiles.
For reptiles that would be Tiktaalik or a relative.
It has been done in a quite detailed fashion for example with horses and whales with fossils and DNA. But it doesn’t matter because you simply dismiss the evidence. We could provide papers detailing this but you wouldn’t accept them . It is much more than I care to type out here. And you are confusing me with the professional biologists here. I am very much the layperson.
Theories aren’t proved, they are confirmed, beyond a reasonable doubt.