![]() ![]() If an analysis of fossils shows a reduced number of bites on and around the forelimbs, as compared to other areas on the body, that might suggest that shortening of the limbs was a successful evolutionary survival strategy. rexes aren’t uncommon in the fossil record. rex fossils as well.īite marks from other T. It's an interesting lesson in survivorship bias but it has some utility in examining T. After all, planes struck in those areas wouldn’t come back. Supposedly, mathematician Abraham Wald flipped the script, suggesting that areas with the fewest bullet holes were the most vulnerable. The initial idea was to protect the areas where bullet holes were most common. War planes would return from the battlefield riddled with holes, and the leadership was tasked with figuring out how to reduce their losses. There’s a famous, possibly apocryphal story involving bullet hole statistics in World War II airplanes. However, we may be able to find indirect supporting evidence in the fossil record. While this explanation for the relatively small size of tyrannosaurid arms is enticing, it runs up against some of the same problems as other explanations, namely the inability for us to test it directly. rex arms became a liability the animal could no longer afford, so they learned to live without them. Bite wounds cause trauma which can lead to infection, shock, and death. The adaptive pressure resulting from the consequences of bite wounds might have overridden any advantage present from having longer arms. Risk of injury is a pretty effective pressure, particularly if the benefits of longer arms are minimal. rex and other tyrannosaurids had larger arms, so there’s a clear evolution in the fossil record showing that some selective pressure pushed tyrannosaurid forelimbs to shrink. Science Photo Library - MARK GARLICK/Getty ImagesĪncestors of T. rex during communal feeding, especially if they were common, then there would have been a selective pressure to reduce the size of the forelimbs to avoid damage.Ĭomputer artwork of a Tyrannosaurus rex dinosaur hunting an Ornithomimus dinosaur. If similar events happened with groups of T. The incident occurred during feeding so it’s unclear if the animal intentionally ate the limb of one of its peers or if it was a result of accidental friendly fire. A video which made the rounds across the internet in 2015 shows a crocodile clamping onto the arm of another croc, rolling, and removing the arm. We see similar behaviors in some modern animals. While that sounds like a happy family sitting around the table together, it might have been highly competitive, with the potential for intentional or unintentional injury. rex participated in group feeding events, where several individuals would descend on a single carcass to eat together. rex might have adapted to avoid being eaten by other rexes. In short, instead of evolving to do something useful, the arms of T. Ideas range from grabbing prey to holding onto mates, but all of those activities would be better served by larger arms, so the mystery has remained.Ī recent paper published in the journal Acta Palaeontologica Polonica suggests a new explanation. Paleontologists have debated the purpose of those arms, dreaming up countless hypotheses to explain away their diminutive size as having some adaptive benefit. Perhaps their most famous feature - the subject of jokes and memes - are their seemingly useless and stubby arms. Their appearance on the landscape would have stricken as much fear into the hearts of their contemporaries as they did viewers of Jurassic Park. ![]() They’re the most famous of the late Cretaceous therapod dinosaurs, apex predators of their time. ![]() For decades the Tyrannosaurs rex has been the mascot of all dinosaurs, and for good reason. ![]()
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