When you look at the paleontology record of the horse, for instance, all the way from the five-toed
Eohippus to the modern horse, what you see is a series of dots separated by millions of years. It may be tempting to assume a gradual change in connecting the dots, but it is only an assumption.
Earth In Upheaval explored a number of the anomalies in the theory of evolution, and makes interesting reading. (The book was also protested vigorously by the evolution establishment, who threatened not to buy
any textbooks from any publisher who dared to print it.) Catastrophic evolution, happening over a generation or two of massive species die-out, has an equally convincing evidentiary basis (i.e., none) as incremental evolution.