The popular avocado belongs to the laurel family, the same group that includes bay leaves and cinnamon. The trees prosper in subtropical climates, and the avocado evolved in the warming climates of Central America 10 million years ago.
The biggest animals on Earth then were megaherbivores – giant animals subsisting almost entirely on a vegetarian diet. Most, like the toxodon, would have dwarfed today’s largest megaherbivore, the elephant.
They needed hundreds of pounds of food a day just to survive. Since leaves and grass are low in calories, the animals prized any energy-dense and fatty foods.
Megaherbivores didn’t peel the avocados and eat the green meat. Instead, they would simply swallow the avocado whole and excrete the undigested pit. The pile of manure would serve as food for the next generation of avocado trees.
As these giant animals roamed and grazed on avocados, they spread the fruit across what is now Mexico.