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Thanks to Damian, who suggested T. rex as a topic! Let’s learn all about the T. rex and especially the most famous and controversial specimen ever found, Sue. A T. rex: Sue, also a T. rex: Show transcript: Welcome to Strange Animals Podcast. I’m your host, Kate Shaw. Our topic this week is a suggestion from Damian, who wants to hear about the one, the only, the tyrant lizard king with massive everything except arms, Tyrannosaurus rex. Aw yeah You probably know a lot about T. rex without realizing it. It’s THE dinosaur, the one people think of first when you say dinosaur. But a lot of popular knowledge about the T. rex is actually out of date, so let’s find out what’s really going on with that big toothy theropod. First of all, T. rex did not live in the Jurassic period. It lived much later, in the late Cretaceous, around 66 million years ago. But I guess Late Cretaceous Park doesn’t have quite the same ring to it. It was one of the last non-avian dinosaurs, dying off in the Cretaceous-Paleogene extinction. It lived in what is now western North America, with close relatives in many other parts of the world. T. rex was a big animal, no doubt about it. The biggest individual we know of, called Sue, stood around 12 feet tall, or a little over 3 ½ meters at the hips. The weight of its massive head was balanced by its long tail. Nose to tail it was around 40 feet long, or about 12 meters. Plenty of other dinosaurs were bigger than T. rex, but T. rex was the biggest land predator we know of. While T. rex had long legs, its arms are famously teeny, only about three feet long, or one meter. That’s barely longer than an adult human’s arm. But recent research shows that the arms weren’t weak. The bones were strong and so were the muscles, although the arm had a limited range of motion and only two toes. Many researchers think T rex used its arms to hold onto struggling prey. Since all we have are fossils, we don’t really know what T. rex looked like beyond its bones and muscles, which we know about from study of muscle attachment sites on the bones. Some researchers think it probably had at least some feathers, since we have feather impressions from some of T rex’s close relations. Baby T rex might have had feathers and shed them as it grew up, or it might have had feathers its whole life. We have fossilized skin impressions from a specimen found in 2002 that show scales on the tail, neck, and hip, so many researchers suggest that T rex only had feathers on its head and back, possibly for decoration or protection from the elements. Closely related species show feather impressions over all of the body, so we know T rex’s cousins were feathered. We also know that T rex had large flat scales on its snout with patches of keratin in the middle, which probably contained sensory bundles. These same patches are present in crocodilians, which help crocs move their eggs and babies without harming them, and help them sense the temperature of their nests. In 2016, researchers discovered that T rex’s teeth contained enamel. This makes the teeth harder, but enamel has to stay damp. That means T rex probably had lips and its teeth wouldn’t have been visible except when the mouth was open. If that sounds weird, most reptiles have lips. Crocodilians don’t, so some of their teeth show when their mouths are closed, but they also live in the water so don’t have to worry about dry mouth. Just to be clear, reptile lips aren’t big kissy lips. They’re just skin that allows the teeth to be completely enclosed within the mouth when the jaws are closed, keeping the mouth from drying out. In 2005, paleontologist Mary Schweitzer found soft tissue in the femur, or thigh bone, of a 68 million year old T rex. The tissue contained blood vessels and a substance called medullary bone, which is only present in female birds right before they lay eggs. Medullary bone helps the bird’s body make shells for her eggs.