So which of these mechanisms do you believe to be impossible, since you are still convinced of "forever separate Kinds"? Especially given that the fossil record has a complete absence of the modern Kinds in the early part (no mammals, no birds)and the loss of a great many Kinds progressively through the record (armoured fish, trilobites, archosaurs, cynodonts, dinosaurs)?Speciation can occur due to mutation or genetic drift and selection. Regarding speciation, there is allopatric speciation where two populations are separated and sympatric speciation where members have a genetic difference which develops into a different population.
Still going with the "fastest runner" theory, even for plants??? There have been plants on land for over 400 million years, but no flowering plants appear in the record until 140 million years ago. Even in your compressed timeframe, its still a mystery you cannot answer (but evolution can).