T. rex
T. rex was about 40 feet long, as long as a school bus. Its hips stood taller than a room. A big adult could weigh about 12,000 pounds.
On this page: how big T. rex was, why the arms were small, possible feathers, and whether it could run.
Read the answer below. In Giant, kids can keep asking T. rex.
T. rex
Tyrannosaurus rex stretched about 40 feet from snout to tail. Its hips were taller than most rooms in a house. Weight estimates land around 12,000 pounds for a big adult. Fossils vary. It walked on two powerful legs. A heavy tail kept it balanced. The skull was huge, with teeth built for crushing bone. It lived at the end of the Cretaceous, about 66 million years ago, in what is now western North America. The name means tyrant lizard king.
~40 ft
Length
~12,000 lb
Weight (est.)
66M yrs
When it lived
North America
Fossil range
The arms were short, but they were not noodles. Muscle scars suggest they were strong for their size. The head and legs did the big jobs: killing, walking, balancing. Tiny arms may have helped hold on close up. They may also have been leftovers as the skull got the starring role. Fossils cannot film the answer, so scientists still argue.
Some close relatives show skin with simple feathers or fuzz, especially when young. Skin prints from big T. rex bodies also show patches of scales. A fair kid version: babies may have had fuzz for warmth. Giant adults likely showed a lot of scaly skin. Movies that make every T. rex a giant chicken are guessing.
Probably not a sprinter like a cheetah. Computer models of that heavy body suggest a fast walk or a short burst, not a long race. Still plenty fast if you were the size of its lunch. Movies love a full-speed chase. Physics is less dramatic.
In Giant
In Giant, kids meet T. rex and ask how big it was, why the arms were small, and whether it could run.
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