There are about 6,000 species of mammals including 1400 species of bats. Insects make up 70% of animal species. It may be that bats are so successful as mammals because they can fly, they eat a lot of insects, the most prevalent animals, and because they can drink your blood!
G. H W. Bush lived the second longest, 94 and change, so Carter was the first to reach 95, 96, etc.