(CNN) Billions of Tyrannosaurus rex roamed North America during their fascinating reign as top predators, according to a team of researchers that went about the daunting task of making the calculation. Paleontologists from the University of California, Berkeley, set out to put a number on how many T. rex lived during the Cretaceous period -- about 65 million to 98 million years ago -- knowing that it wouldn't be a simple task. "There is just no information to make the estimate," explained Charles Marshall, director of the University of California Museum of Paleontology, who was part of the research team. "If you find an Easter egg in your garden, how can you estimate how many Easter eggs that have ever existed? You need information from somewhere else -- for example, the density of Easter eggs, the area over which eggs might be found, and for how many years Easter eggs have been placed in gardens."

Source: CNN April 15, 2021 23:48 UTC