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T-Rex’s comically tiny arms may have been used as weapons or during sex

Our understanding of the Tyrannosaurus Rex has changed quite a bit over the years.

Since we first discovered fossils of the T-Rex in 1874, we have learned more about what they looked like, what they ate and how they stood.

For example, we know they might have had feathers at some point during their evolution. We also know that they had cannibalistic tendencies and that they did not – contrary to popular belief – walk upright.

Something that hasn’t really changed is our knowledge of the T-Rex’s comically tiny arms, which have typically been regarded as a vestigial feature inherited from its ancestors.

Vestigial traits are those that no longer serve a function. In humans, an example is the formation of goose bumps.

In times of stress, we used to get them because they would make the hairs on our body stand up so that we would appear bigger when threatened. Obviously, this doesn’t work anymore, but we still get goosebumps.

But recently, two competing theories have suggested that those tiny wittle T-Rex arms may have indeed been pretty darn useful.

T Rex humping

T-Rex sex may have looked like this. You’re welcome.

One theory comes via Dr Steven Stanley, a palaeontologist at the University of Hawaii at Manoa. According to Stanley’s theory, the T-Rex’s arms were, in fact, vicious weapons that were used in combat.

“Its short, strong forelimbs and large claws would have permitted T. Rex, whether mounted on a victim’s back or grasping it with its jaws, to inflict four gashes a metre or more long and several centimetres deep within a few seconds,” he said at a geological conference in Seattle.

Stanley argues that the T-Rex actually had strong arm bones attached to the body with unusual joints that could move around in a slashing action.

Other experts aren’t convinced.

“It seems illogical to me to use such small arms to slash with,” paleobiologist from the University of Bristol Jakob Vinther told National Geographic.

Vinther sides with the camp that believes the T-Rex’s arms served the “minor subsidiary purpose” of grabbing a partner during sex.

Fighting and humping are both very important things when it comes to evolution so there’s a pretty good chance one of the sides is right.

Otherwise, those arms may just be like our goosebumps, an evolutionary hangover the T-Rex got stuck with. At the moment, this still seems to be the general consensus among scientists.

About the author

Stefan is an Adelaide-based freelance writer. In his spare time, he plays tennis badly, collects vinyl and brushes up on his Mandarin. Follow Stefan on Twitter

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