14/06/2026

theSunday Special V ON SUNDAY JUNE 14, 2026

How T-Rex ended up having oversized head, puny arms

T yrannosaurus Rex possessed a preposterously massive skull – 1.5m long and built to enable bone-crunching bite force – but presented preposterously puny arms. And many other meat-eating dinosaurs shared this mismatched combination of traits. So, how did this come to be? Researchers studying this phenomenon have now documented how skull robustness in meat-eating dinosaurs started to evolve first, as plant-eating dinosaurs that they hunted became bigger soon after dinosaurs became Earth’s Researchers suggest dinosaur’s forelimbs grew redundant, whereas big skulls stayed useful

appearance of ever-larger plant-eaters, including the long-necked sauropods. “Body size in dinosaurs increased massively from the Triassic to the end Cretaceous, so it’s likely that the increase in body size drove some theropods to shift towards using their heads more than their limbs in hunting. Effectively, the forelimbs became redundant in hunting. “Natural selection will act on the traits which allow an animal to survive and thrive in its ecosystem. If that means sacrificing the size of the arms for a stronger head, which is the primary weapon for the animal, then that’s likely what will happen,” said Charlie Scherer, a University College London doctoral student in paleontology and lead author of the study published in the journal Proceedings of the Royal Society B . Reuters reported the researchers created a new methodology for quantifying skull robustness based on traits that included skull dimensions, bite force, tooth shape and cranial bone fusion patterns. Tyrannosaurus, which lived in North America during the Cretaceous, scored the highest, followed by Tyrannotitan of Cretaceous South America. A close association The researchers found that skull robustness was closely associated with forelimb reduction. The theropod lineages in which this phenomenon occurred were tyrannosaurs including Tyrannosaurus, carcharodontosaurs including Carcharodontosaurus of Cretaceous Africa, megalosaurs including Megalosaurus of Jurassic England, ceratosaurs including Ceratosaurus of Jurassic North America and Europe and abelisaurs including Abelisaurus of Cretaceous South America. These lineages included apex predators that relied on large body size and strong jaws to tackle various types of large plant eating dinosaurs that included sauropods, horned dinosaurs, armored dinosaurs and duck-billed dinosaurs. One of the earliest theropods to exhibit this phenomenon was Eoabelisaurus, which lived in Jurassic South America

dominant land animals, leading to a subsequent reduction in the arms. They identified five lineages of theropods – the two-legged group that spans all the meat-eating dinosaurs – in which this phenomenon independently appeared, underscoring the evolutionary advantages that drove these traits. T-Rex’s tiny arms have long been the object of fascination, even spawning online memes mocking the fearsome predator’s inability to do things such as clap its hands, scratch its nose or perform a push-up. Dinosaurs first appeared roughly 230 million years ago during the Triassic Period, then dominated the landscape during the subsequent Jurassic and Cretaceous Periods before being doomed by an asteroid strike 66 million years ago. The earliest theropods had well developed arms useful for subduing prey, but that changed following the

The puny arms of the T-Rex are the subject of many jokes. – REUTERSPIC about 170 million years ago. Some lineages of large theropods retained long and strong arms. These included such dinosaurs as Spinosaurus of Cretaceous Africa and Megaraptor of Cretaceous South America. These theropods “have incredibly large and mobile arms for their body size, which suggest a more prominent role for them in hunting compared with something such as T-Rex,” Scherer said. Small theropods also kept useful arms, including the lineage that led to birds. For theropods such as Tyrannosaurus, scientists are not sure what function small arms served. Not only were the length and strength of the arms of Tyrannosaurus diminished, but it retained only two fingers on its hands. “Potentially, they did nothing with them – they were just useless. This raises the question: Why did they have tiny arms, rather than no arms? If the tiny arms are still there, then it is possible that they still retain some kind of function that we are not aware of. For me, however, this is unlikely, and I think something else is going on,” said University College London paleontologist and study co-author Paul Upchurch. When an anatomical structure is no longer helpful, genetic changes can result in its reduction so the animal does not waste energy and resources building something it does not need, Upchurch said. “But we know that genetics is complicated and very often genes have more than one role. For example, a gene might be involved in building something that the animal no longer needs, but the same gene might also be doing something in another part of the body that the animal does still need. This means that the gene is maintained because it is still doing something useful, so the useless structure persists in a reduced form rather than disappearing completely,” Upchurch said.

A Tyrannosaurus Rex specimen named Sue at the Field Museum in Chicago. – FIELD MUSEUM HANDOUT VIA REUTERS

Swedish expert on mission to bring Jurassic era to life TWO hundred million years ago, the land that became

“It was kind of surprising to see that it was such lush vegetation,” she added. The dense greenery was made up of ferns, primitive conifers and marsh plants, a far cry from today’s Scandinavian landscapes. The clues provided by the fossils provide “only a snapshot of one time interval, a short time... in which we have a window into the past”. “But then, we have older and younger (fossils) and we can compare how climate change and biodiversity changed over time. It’s always nice to see what it actually looked like and make the plants and animals come to life,” she said.

tooth or a leaf imprinted in rock, all carefully preserved in the museum archives – the researchers identified the animal and plant species to which they belonged, then pieced them together with the help of an illustrator to recreate a local Jurassic ecosystem. “I was myself surprised about the biodiversity because it was the first time we actually put all the animals and plants we had in these rocks together in one ecosystem,” she said. The result very likely reflects what life looked like on the ground “because we find them in the same area, within a few hundred metres of rock”.

her mind whenever she saw a rock or a fossil gradually took shape over the course of her fieldwork. “I really felt we lacked a book with illustrations that actually shows scientifically, with a very strong scientific base, what it looked like in Sweden 200 to 100 million years ago during the Jurassic period.” ‘Snapshot’ With her team, she set herself the task of reconstructing entire ecosystems from that period. The illustrations were published in a book in October 2025. Starting from each fossil fragment – such as a footprint, a

collected in the field,” she said, pointing to what looks like brown and yellow spots, round and rectangular in shape. Most of the Jurassic-era fossils found in Sweden have been discovered in Skane, preserved thanks to deep cracks in the ground that protected them from the many ice ages that erased traces in the rest of Sweden. “I’m interested in what forests there were like during the Jurassic period, so when I see a pollen grain, I actually see the tree. I can see the tree and the ecosystem in front of me,” she said. The idea of showing the general public what appeared in

southern Sweden was covered in lush vegetation where crocodiles and dinosaurs roamed, an era palaeontologist Vivi Vajda and her team have set out to reconstruct. In a wing of Stockholm’s Museum of Natural History, the researcher recently welcomed AFP to her office, scattered with books and fossil samples. Sitting behind her microscope, Vajda examined specimens collected in Sweden’s southern Skane province, projecting them onto the wall with an overhead projector. “This is a pollen sample that I