The T-Rex was one of the scariest dinosaurs, with huge teeth. But why did it have such small arms? A team of scientists from University College London and Cambridge University studied 82 types of theropod dinosaurs to find the answer. They discovered that the T-Rex's small arms might be connected to its big and powerful head and jaws. This means that the T-Rex needed strong jaws to catch its prey, not strong arms. Did you know that the T-Rex's arms were smaller than some other dinosaurs? Scientists think that the T-Rex's small arms might be because of what it ate. The T-Rex mainly ate plant-eating dinosaurs, which were getting bigger and bigger. Scientists believe that the T-Rex used its strong jaws to catch its prey, not its arms. This meant that its arms didn't need to be as strong, so they got smaller over time. As scientists say, 'If you don't use something, it gets smaller.' The T-Rex's small arms are something that kids might wonder about. But these small arms, along with its big and powerful jaws, made the T-Rex one of the scariest dinosaurs. The T-Rex's small arms can help kids learn about how nature works and how animals evolve. It can also help them learn about how dinosaurs like the T-Rex lived and died.