Affiliate Marketing Secrets

1)
A higher surface area-to-volume ratio facilitates heat loss.
2)
Animals in warmer climates need to move more quickly to catch prey.
3)
More species inhabit warm climates, and smaller size enables a greater number to live in the same ecosystem.
4)
Smaller body size enables faster reproduction and repopulation to maintain a niche in overpopulated warmer climates.

I started pondering this as I was reading about what would happen if the amazon rainforest died.
Mostly it seems that global temperatures would rise due to carbon dioxide levels in the atmosphere rising. Most animals would die off or be forced to adapt, and humans would suffere a massive die-off world-wide.
Somewhere else, I read that a similar catastrophe is believed by some to be what allowed dinosaurs to evolve.
Now, I severly doubt something like T-rex would evolve again (though its certainly possible, since afterall it did happen once), but if animals like grizzly bears and lions and elephants and such died out, wouldnt that leave niches open for other animals to occupy in the far distant future, and wouldnt reptiles be more likely to survive in the warmer climate than mammals?
The only thing that puts that to question is that to my knowledge most reptiles are struggling, meaning a lot of them (if any) may not make it into the far distant future if such a catastrophe were to happen.
Is it possible? Could dramatic climate change actually cause reptiles to grow larger and take the niches that are now dominated by mammals?
I dont know if such a climate change is coming, and either way i obvously wont live long enough to see this myself, but its a fun idea, isnt it?