Ever wonder just how many members of a species has lived? A bunch of scientists wondered about that … for the venerable Tyrannosaurus rex. Here’s the abstract on their paper:
Although much can be deduced from fossils alone, estimating abundance and preservation rates of extinct species requires data from living species. Here, we use the relationship between population density and body mass among living species combined with our substantial knowledge of Tyrannosaurus rex to calculate population variables and preservation rates for postjuvenile T. rex. We estimate that its abundance at any one time was ~20,000 individuals, that it persisted for ~127,000 generations, and that the total number of T. rex that ever lived was ~2.5 billion individuals, with a fossil recovery rate of 1 per ~80 million individuals or 1 per 16,000 individuals where its fossils are most abundant. [Science]
Wow! But what’s the confidence level?
The uncertainties in these values span more than two orders of magnitude, largely because of the variance in the density–body mass relationship rather than variance in the paleobiological input variables.
Two orders of magnitude is a lot. But what fun, thinking of 2.5 billion hungry Tyrannosaurus rex critters running around .. looking for a bite to eat.
