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 North America
 68 million years ago

Mean atmospheric O2
 150% of modern level

Mean atmospheric CO2
 6x pre-industrial level

Mean temperature
 4C above modern level

Mesozoic Earth - An extinct Tyrannosaurus rex compared to a modern polar bear; theropod; bipedal carnivore; apex predator; scavenger; tyrannosaurid; T-Rex; T. rex; King of the Dinosaurs; scale reference - Natural History Illustration Geologic Time Scale

 Era: Mesozoic
  Period: Cretaceous
   Epoch: Late
    Age: Maastrichtian


Tyrannosaurus rex & polar bear compared

A coelurosaurian theropod dinosaur of the species Tyrannosaurus rex from 68 million years ago is compared to a modern adult male polar bear (Ursus maritimus). The Tyrannosaurus rex is about 13 feet tall at the hip, 40 feet long and weighs seven tons* while the polar bear stands 10 feet tall and weighs 1,400 pounds.

The polar bear is currently the largest terrestrial predator in the world while Tyrannosaurus rex was the largest known tyrannosaurid and one of the largest known predators ever to have walked the earth.

* Values are estimates only based upon available paleontological data.



Copyright Walter B. Myers. All rights reserved.

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