“2.5B T. Rexes Roamed North America over the Cretaceous Period”

>the uncertainties in the estimates are large. While the population of T. rexes was most likely 20,000 adults at any give time, the 95% confidence range — the population range within which there’s a 95% chance that the real number lies — is from 1,300 to 328,000 individuals. Thus, the total number of individuals that existed over the lifetime of the species could have been anywhere from 140 million to 42 billion.

So could have been anywhere from, far less than the amount of wolves now to almost half the amount of humans that have ever lived.