Darwin (1) near consistently included each and every argument & counter-argument to the point where it becomes boring and unreasonable to go any further (2) was

Darwin (1) near consistently included each and every argument & counter-argument to the point where it becomes boring and unreasonable to go any further (2) was absolutely explicit of what was NOT included to the point that there were redunant remarks about that! --- The view of Smith is laughable, for the human population has changed by more than few orders of magnitude since those times. Yet it would be plausible that a global MF ecosystem was distrupted somehow. Another possible reason megafauna died: they eat plants and grew on top of an ecosystem where there was not much competition for plants, and then an increase in efficiency of bacteria, bugs, invertebrates and other compact herbivore species in consumption of the limited amount of plant food pulled the legs under them. Whales were not herbivores, and possibly therefore not subject to same mechanisms (though saying this sort of ruins the metaphor of pulling legs from underneath).