If there are versions of the evolution theory that deny slow gradualism, and deny the central role of natural selection, they may be true in particular cases. But they cannot be the whole truth, for they deny the very heart of the evolution theory, which gives it the power to dissolve astronomical improbabilities and explain prodigies of apparent miracle. Macro-evolution has always needed as much time as it can get for it's undirected naturalistic mechanisms to work. However improbable we regard this event, or any of the steps which it involves, given enough time it will almost certainly happen at least once. And for life as we know it, with its capacity for growth and reproduction, once may be enough.
Time is in fact the hero of the plot.
The time with which we have to deal is of the order of two billion years. What we regard as impossible on the basis of human experience is meaningless here. Scientific American, vol. It may be claimed that 5 million years is a lot of time, but in palaeontological terms it isn't. It important to actually look at the sketches in Discover, to appreciate the magnitude of these changes.