You really never seem to recall what was posted in previous threads about the subject, no matter how many times we have had this discussion. The general consensus at present is that human hunting had a major impact on the extinction of megafauna in many parts of the world.
Wait - are you going with tropical as “situated between the tropics of Capricorn and Cancer” here, or the Köppen-style classification? I know, either way, the savanna herds are in, so your overall point is spot-on, but the latter method is going to exclude camels and big kangaroos.
Yes, more a Köppen-Geiger system. Us botanist types do incline toward vegetative models. 
And please note I said “exclusively tropical”. Australia has only a small area of tropics, and the majority of species that graze African savannas are not restricted to the tropics.
Note also the reality that, while African savanna herds are vast, the savanna itself is far vaster. One must still be in a fortunate location to take advantage of that bounty. I think this can be described as “overall abundant in terms of biomass but locally highly dispersed”.
The discussion was not limited to Africa. I offered some generalizations, exploring some possible differences between successful hunter gatherer strategies in generic tropical versus generic temperate areas. Other than a blanket condemnation and some snark, I have not seen any actual refutation. I will gracefully accept detailed enlightenment of my errors. However, I really do not understand what I am perceiving as hostility.
Nor do I deny “a major impact”. But “a major impact” does not mean all of it, by itself. Scientists argue just how much of an impact, and yes, many think human hunting had “a major impact”. But afaik, no scientist has shown that humans caused 100% of the extinctions, nor was hunting the only human impact.
In fact here in this 2007 article, we have a view that climate changes are the major culprit.
" *And then, about 13,000 years ago, most of this fabulous megafauna rapidly died out. Mammoths went extinct. Lions and tigers and horses and sloths disappeared. Scientists have long debated the causes.
Was it overhunting by Pleistocene humans with spears, wild fire and shrewd killing strategies? Or was it a sudden shift in the climate that destroyed the productive grassy steppe that supported this network of grazers and their predators?
Now, an international team of scientists led by Richard Firestone of Lawrence Berkeley National Laboratory has uncovered evidence that an immense explosion - accompanied by a nuclear-strength shockwave - triggered a catastrophic climate shift that wiped out life across America. The work follows up on earlier findings by Firestone that a supernova 41,000 years ago may have created a killer space rock and sent it tumbling into the home planet."*
You seem to read my statement of “Human hunting was not the only cause” as = “human hunting had no impact at all”. This is not true, human hunting certainly had a significant impart.
Nor does “in many parts of the world” equate to everywhere, and it seems like the evidence for NA is weaker. But true- in some areas, and some species- human hunting was apparently by far the most significant. In others- not so much.
Let us look at the Mammoth. In NA I could have counted the number of confirmed human kill fossils on one hand (maybe now I’d have to take off my shoes). In EU, there are that many sites- in at least one, with hundreds, perhaps thousands, of mammoth kills with the bones stacked by type! No kill/slaughter site as big as that has been found in NA. Perhaps there are sites not yet found, but it certainly looks like humans didn’t hunt Mammoths in NA in anywhere near the scale they did in EU.
Here’s another article from 2001. This article is good as it hows one scientist with figures that support humans as the main cause, and another doubting those figures. Thus there is significant debate on this subject.
They actually present three arguments of what was the primary cause: human hunting , human introduced hyperlethal disease, or climate.
…"paleoecologist John Alroy of the University of California at Santa Barbara argued that, in fact, hunting-driven extinction is not only plausible, it was unavoidable. He has determined, using a computer simulation, that even a very modest amount of hunting would have wiped these animals out. "…
"Not everyone agrees with Alroy’s assessment. For one, the results depend in part on population-size estimates for the extinct animals–figures that are not necessarily reliable. But a more specific criticism comes from mammalogist Ross D. E. MacPhee of the American Museum of Natural History in New York City, who points out that the relevant archaeological record contains barely a dozen examples of stone points embedded in mammoth bones (and none, it should be noted, are known from other megafaunal remains)–hardly what one might expect if hunting drove these animals to extinction. …
MacPhee agrees that humans most likely brought about these extinctions (as well as others around the world that coincided with human arrival), but not directly. Rather he suggests that people may have introduced hyperlethal disease, perhaps through their dogs or hitchhiking vermin, which then spread wildly among the immunologically naive species of the New World."…
“The third explanation for what brought on this North American extinction does not involve human beings. Instead its proponents blame the loss on the weather. The Pleistocene epoch witnessed considerable climatic instability, explains paleontologist Russell W. Graham of the Denver Museum of Nature and Science.”
Thus, there is room for debate, especially in NA. Not that I am saying that human hunting was not a significant cause with some species in some areas. It certainly appears to have been so.
DrDeth, I’m not at all interested in hijacking this thread any further by getting into yet another discussion of this subject with you. Of course, no scientist has said that humans caused all of the extinctions, or that hunting was the only cause. But as I said, the general consensus today is that humans, in particular through hunting, were a major factor in causing megafaunal extinctions in many areas.