@mcc using overly generous estimates, let's assume a median number of a thousand extant simian species at any given year, a median simian population of 1 million individuals per species per generation, and a median generation time of 10 years. Atliatlassius is a fine enough spot to start the clock, which i'll round to 60 million years in the interest of conservatism and keeping only one sig fig.

so that gives 6 * 10⁶ * 10⁶ * 10³ / 10¹ = 6 * 10^14, or a lower bound of 600,000,000,000,000, or a mere 600 quadrillion monkeys, as a conservative lower bound.

edit: fix typo and clarify simians, not all primates, which would probably add another zero.