Word Wednesday: Tyrannosaurus rex

The Tyrannosaurus rex is one of the most well known dinosaurs and is one of very few that people know both the genus and species name. Like the word ‘dinosaur’, you probably already have a good idea of what it means.

Tyrannosaurus rex

Let’s take this one word at a time. Tyrannosaurus breaks down into tyranno and –saurus. Tyranno comes from the Greek word ‘tyrannos‘ which means lord or master  and saurus comes from the Greek word ‘sauros‘ which means lizard. The species identifier, rex, is a Latin word which means king. Putting it all together, Tyrannosaurus rex means master lizard king. Evidently H.F. Osborn, who named Tyrannosaurus rex in 1905, thought very highly of the dinosaur. It lived during the late Cretaceous in what is now western North America. It is known in pop culture as a fearsome predator, but there is still debate within the scientific community as to whether it was a predator or a scavenger.

Tyrannosaurus rex skeleton (the specimen AMNH 5027) at American Museum of Natural History. (by J.M. Luijt)

In the past, reconstructions of T. rex depicted it standing upright with its tail dragging on the ground. Modern reconstructions have the back nearly parallel to the ground with the tail as a counterbalance to its heavy head. This would allow the dinosaur to run faster and have more maneuverability. Plus, think about it this way: when a beaver drags its tail (which only weighs a few pounds) along the ground it leaves an indentation. A T. rex tail (which weighs thousands of pounds) would leave a massive indentation if it were dragged around. However, no T. rex trackways have associated tail indents. 

Many people have probably done T. rex impressions, mocking their short arms. Despite having short arms, the bones have evidence of massive muscle attachments. Why have short, strong arms? Scientists aren’t sure, but suggest ideas ranging from aiding during copulation to helping the dinosaur stand up if it fell or laid down to acting as meat hooks when it ate. Until someone invents a time machine, we may never know the answer.

Most importantly, whenever you are doing a T. rex impression, remember that they only had 2 fingers (Allosaurus had 3). To learn more about the Tyrannosaurus rex, check out the links below!

Could you outrun a Tyrannosaurus rex?

T. rex Poo Headed to the Smithsonian Museum

Just when you thought it was safe to go back in the water: Scientists reveal ‘dino paddle’ T-Rex used to wade across rivers


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