Short answers, pulled from the story.
Recent molecular studies suggest that cacti evolved around 35 to 30 million years ago during the very Late Eocene to early Oligocene periods. Older sources previously suggested an origin between 90 and 66 million years ago during the Late Cretaceous.
The three main centers of diversity for drought-adapted cacti are the deserts of North America, the southwestern Andes found in Peru Bolivia Chile and Argentina, and the Caatinga of eastern Brazil. These regions support the highest concentration of species adapted to arid conditions.
Peyote Lophophora williamsii in North America and the San Pedro cactus Echinopsis pachanoi in South America both contain mescaline. Evidence indicates peyote was in use more than 5,500 years ago with radiocarbon dating showing dried buttons from 3780 to 3660 BC.
Detailed treatments published in the 21st century divide the family into around 125 to 130 genera and 1,400 to 1,500 species. The International Cactaceae Systematics Group recognizes four subfamilies within this total count.
Rhipsalis baccifera is the only cactus native to both the Americas and the Old World including tropical Africa Madagascar and Sri Lanka. One theory suggests it spread by being carried as seeds in the digestive tracts of migratory birds.