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  "path": "/science/palaeontology-breakthrough-trex-tiny-arms-university-cambridge-college-london",
  "publishedAt": "2026-05-20T12:38:23.000Z",
  "site": "https://www.gbnews.com",
  "tags": [
    "Millions of people set to gather for ‘once-in-a-century’ total eclipse",
    "Highly venomous new species discovered lurking in waters just off major city",
    "Scientists solve mystery behind noises that haunted generations of lighthouse keepers",
    "The GB News Editorial Charter"
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  "textContent": "\n\n\nScientists may have finally cracked one of palaeontology's most enduring puzzles: the Tyrannosaurus rex’s famously tiny arms.\n\nA new study by researchers at University College London (UCL) and the University of Cambridge suggests the answer lies not in the arms themselves, but in the dinosaur's extraordinarily powerful head.\n\n###\n\n\n\n\nThe research found smaller arms in meat-eating dinosaurs were closely linked to the development of large, robust skulls and jaws, rather than simply being a by-product of growing overall.\n\nPublished in the journal Proceedings of the Royal Society B, the study examined data from 82 species of theropod, the group of two-legged, predominantly meat-eating dinosaurs that includes T. rex.\n\n###\n\n\n\n\nTRENDING\n\nStories\n\nVideos\n\nYour Say\n\n###\n\n\n\n\nResearchers identified five groups of theropods that evolved shortened forelimbs, including tyrannosaurids, abelisaurids, carcharodontosaurids, megalosaurids and ceratosaurids.\n\nThe team found in each case, the reduction in arm size had a stronger association with skull robustness than with overall body size, suggesting the two developments were directly connected.\n\nLead author Charlie Roger Scherer, a PhD student at UCL Earth Sciences, said the findings pointed to a clear evolutionary logic.\n\nHe said: \"Everyone knows the T. rex had tiny arms, but other giant theropod dinosaurs also evolved relatively small forelimbs.\n\n###\n\n\n\n\n###\n\n\n\n\n###\n\n\n\n\n“The Carnotaurus had ridiculously tiny arms, smaller than the T. rex.\"\n\nMr Scherer said the research revealed a strong relationship between short arms and large, powerfully built heads, with the head effectively taking over from the arms as the primary method of attack.\n\nHe said: \"It's a case of 'use it or lose it' - the arms are no longer useful and reduce in size over time.\"\n\nThe researchers believe the trigger for this evolutionary shift was the emergence of increasingly gigantic prey, including enormous sauropods, the long-necked, long-tailed plant-eating dinosaurs that could reach lengths of around 100ft.\n\n### LATEST DEVELOPMENTS\n\n\n\n\n  * Millions of people set to gather for ‘once-in-a-century’ total eclipse\n  * Highly venomous new species discovered lurking in waters just off major city\n  * Scientists solve mystery behind noises that haunted generations of lighthouse keepers\n\n\n\n###\n\n\n\n\n###\n\n\n\n\nMr Scherer said: \"Trying to pull and grab at a 100ft-long sauropod with your claws is not ideal.\n\n“Attacking and holding on with the jaws might have been more effective.\"\n\nThe team described the process as an \"evolutionary arms race\" in which theropods developed increasingly strong skulls and jaws to better subdue increasingly large prey, whilst their forelimbs became progressively redundant.\n\nMr Scherer added: \"It is highly likely that strongly built skulls came before shorter forelimbs.\n\n###\n\n\n\n\n###\n\n\n\n\n“It would not make evolutionary sense for it to occur the other way round, and for these predators to give up their attack mechanism without having a backup.\"\n\nTo measure skull strength, the researchers developed a new method of quantifying skull robustness, taking into account factors including how tightly connected the skull bones were, the overall dimensions and shape of the head and estimated bite force.\n\nOn that measure, the T. rex scored highest of all the species examined, confirming its status as one of the most formidably equipped predators in prehistoric history.\n\nIt was followed closely by the Tyrannotitan, a theropod of comparable size that lived in what is now Argentina during the Early Cretaceous period, more than 30 million years before T. rex walked Earth.\n\n###\n\n\n\n\n###\n\n\n\n\nThe study also found the pattern of arm reduction differed between species, with hands and the lower portion of the arm shortening most dramatically in abelisaurids, while in tyrannosaurids each element of the forelimb reduced at a broadly similar rate.\n\nOne example highlighted by the researchers was the Majungasaurus, which resided in Madagascar around 70 million years ago.\n\nThe apex predator had an exceptionally powerful skull and tiny arms despite weighing only around 1.6 tonnes – roughly a fifth of the T. rex's body weight.\n\nIts inclusion in the findings helped reinforce the point that small arms were driven by skull development rather than sheer body size.\n\nThe team concluded that while the same outcome of reduced forelimbs appeared across multiple groups of dinosaurs, it was likely achieved through different developmental pathways in different species.\n\nPrevious theories had proposed alternative explanations for the T. rex's reduced arms, including suggestions they aided balance, helped the animal stand upright after falling, or played a role during mating.\n\n###\n\n\n\n\n**Our Standards: The GB News Editorial Charter**",
  "title": "Palaeontology breakthrough as scientists discover reason why T-Rex had tiny arms"
}