One Tyrannosaurus rex appears scary sufficient. Now image 2.5 billion of them. That’s how lots of the fierce dinosaurs most likely roamed Earth over the course of a pair million years, a brand new examine finds.
Using calculations based mostly on physique dimension, sexual maturity and the creatures’ vitality wants, a group on the University of California, Berkeley discovered simply what number of T. rex lived over 127,000 generations, based on a examine in Thursday’s journal Science.
It’s a first-of-its-kind quantity, however simply an estimate with a margin of error that’s the dimension of a T. rex.
“That’s a lot of jaws,” stated examine lead creator Charles Marshall, director of the University of California Museum of Paleontology.
“That’s a lot of teeth. That’s a lot of claws.”
The species roamed North America for about 1.2 million to three.6 million years, that means the T. rex inhabitants density was small at anybody second. There can be about two in a spot the dimensions of the Washington, or 3,800 in California, the examine stated.
“Probably like a lot of people, I literally did a double-take to make sure that my eyes hadn’t deceived me when I first read that 2.5 billion T. rexes have ever lived,” stated Macalester College paleobiologist Kristi Curry Rogers, who wasn’t a part of the examine.
Marshall stated the estimate helps scientists determine the preservation price of T. rex fossils and underscores how fortunate the world is to learn about them in any respect.
About 100 or so T. rex fossils have been discovered — 32 of them with sufficient materials to determine they’re adults. If there have been 2.5 million T. rex as a substitute of two.5 billion, we might most likely have by no means identified they existed, he stated.
Marshall’s group calculated the inhabitants through the use of a common biology rule of thumb that claims the larger the animal, the much less dense its inhabitants.
Then they added estimates of how a lot vitality the carnivorous T. rex wanted to remain alive — someplace between a Komodo dragon and a lion. The extra vitality required, the much less dense the inhabitants.
They additionally factored in that the T. rex reached sexual maturity someplace round 14 to 17 years previous and lived at most 28 years.
Given uncertainties within the creatures’ era size, vary and the way lengthy they roamed, the Berkeley group stated the entire inhabitants may very well be as little as 140 million or as a lot as 42 billion with 2.four billion as the center worth.
The science in regards to the greatest land-living carnivores of all time is vital, “but the truth, as I see it, is that this kind of thing is just very cool,” stated Purdue University geology professor James Farlow.