Stamp Stories: Tyrannosaurus Rex

Maureen: Hi, I’m Maureen from the National Postal Museum.

Amy: And I’m Amy from the National Museum of Natural History.

Maureen: Welcome to Stamp Stories, where we explore topics that appear on postage stamps. New stamps come out every year on wide variety of topics. Today we’re going to learn about Tyrannosaurus rex.

Amy: Tyrannosaurus rex is possibly the most well-known fossil animal of all time. They have fascinated us for decades with their incredible size, powerful jaws and teeth, and their sudden extinction. Let’s learn a little more about what scientists know about Tyrannosaurus rex.

Tyrannosaurus rex is one of the most famous dinosaurs of all time. These massive hunters captivate us, and paleontologists have spent decades learning as much as they can about these creatures. Tyrannosaurus rex lived from about 68 million years ago until 66 million years ago, and they lived right here, on the continent that we now call North America. If you live in parts of the western United States or Canada, there could have been a T. rex in your neighborhood!

T. rex are members of a group of dinosaurs called theropods. Did you know that some descendants of theropods are still alive today? You know them by a much more familiar name – birds! And, birds aren’t the only dinosaurs that evolved feathers – we have some fossil evidence that many other theropods, even some tyrannosaurs, had them too!

Like all dinosaurs, Tyrannosaurus rex hatched from small eggs. This is a fossil egg from another theropod called Allosaurus, and this egg is only about 11 cm long. Even the largest dinosaurs like sauropods would hatch from eggs no larger than a football, meaning that baby T. rexes must have been tiny compared to their full-size parents. While no eggs or baby T. rexes have ever been found by paleontologists, we have found juveniles and even embryos, which are the tiny bodies still growing inside eggs that have not yet hatched, of other tyrannosaurs. These fossils can help us understand how tyrannosaurs grew and developed, giving us insight into many aspects of their life history.

The name Tyrannosaurus rex means “King of the tyrant lizards,” and that name is accurate! T. rex was a carnivore, and an impressively powerful one at that. Based on reconstructions of the bite force their jaws could generate, their jaws were some of the strongest of any animal ever to have lived. Their sharp teeth were serrated, or saw-toothed, along the back edge. This gave them the ability to tear through meat like a knife. Like crocodiles and all dinosaurs, T. rex would shed and grow new teeth throughout their lives, and we find many of these isolated teeth in the fossil record.

We have evidence that T. rex ate many kinds of dinosaurs. Everything from hadrosaurs, ceratopsians like Triceratops, and ankylosaurs were on the menu. We know this because we have fossils of many of these animals with bite marks on their bones that perfectly match T. rex teeth, and there’s even a fossil vertebra (back bone) from a hadrosaur with a T. rex tooth embedded in the bone. Like most carnivores, perhaps they preferred to pick juveniles or other vulnerable animals for dinner. But when those weren’t available, there’s some evidence that T. rex would turn to another source of food – each other. Some fossil bones from T. rex have been found with serrated tooth marks that match the teeth of other T. rexes.

Since T. rex was so strong, it would make sense to assume that they could run very quickly, right? However, there’s still a lot of debate over just how fast the tyrannosaurs, and T. rex especially, could really run. While we sometimes picture T. rex sprinting after its prey at high speeds, we don’t think they would have been able to run quickly in life. T. rex was probably too heavy to run quickly, and the amount of muscle development they’d need to sprint would be unsustainable. While the T. rex’s maximum walking speed may not have been higher than 15 miles per hour, this was still fast enough to chase down other, slower-moving dinosaurs.

Maureen: Thanks for sharing all that with us, Amy! It’s so interesting to hear how scientific ideas about Tyrannosaurus rex have changed as new discoveries and information are uncovered. Let’s take a look at a book that explores this a little more.

This book is called Dinosaurs Can’t Roar: the Unbelievable True Story About T Rex and our Dino Friends. It’s written by Layla Beason and illustrated by Mariano Epelbaum. Many thanks to Sourcebooks for permission to use this book.

Amy: We all love dinosaurs. We love them a lot. We know what they are. We know what they are not. But is that true? New science might show we should probably question all that we know.

Maureen: We’ve seen the T. Rex colored from green to blue, or orange and stripy, and some in shirts, too! Some were funny, some scary, some downright cute. Meet our friend, Rex (please note the round snoot)!

Amy: Our doctor of dinos has some thoughts about Rex. Get ready for change – this is somewhat complex. Rex should be lower, with his nose to the ground. Rex won’t like this at all, and he makes an odd sound.

Maureen: We’ve seen Rex look tall, just straight up and down, with his head in the sky and his tail on the ground, but the doctor declares the posture that’s best is his head pointing east and his tail pointing west.

Amy: Now let us consider T. rex’s arms – they’re silly and short, not the best of his charms. Rex was embarrassed his arms were so small. He couldn’t take pictures or catch a ball!

Maureen: Rex didn’t know that his small arms instead let the muscles grow strong in his neck and his head. With powerful strength from his back through his jaws, he didn’t need long arms…well, just because.

Amy: Next shall we talk about Rex’s real look? He wasn’t the cutie pie seen in this book. While scientists found Rex indeed had some scales, he likely had feathers from head down to tail!

Maureen: Okay, maybe Rex didn’t look like a chick. He had a few feathers, but was still pretty slick. The feathers were colorful, but not absurd, as Rex was less reptile, and way more a bird.

The doc said we’re not done. Science found more! Rex called to his friends to see what was in store. Triceratops, Stegosaurus, Brontosaurus too! These dinos are about to learn something new.

Amy: Triceratops, famous for horns and a crest, really wore a bigger and brighter headdress. But it’s not like a feathered peacock, in fact. To say it’s a shield would be much more exact.

Maureen: A brain in the butt AND a brain in the head? That theory seems silly, but it’s what people said! Over time, our theories can change. That is true! Now we know Stegosaurus had one brain, not two!

Amy: The Brontosaurus existed, said science in chorus until they thought, Nope, that’s an Apatosaurus! “Bring her on back,” the doc started to shout. “We were right the first time, as it turns out!”

Maureen: Though these dinosaurs seem like the perfect friend squad, if they really hung out, it would’ve been odd. Our doc said two friends came millions of years before Rex and Triceratops ever appeared!

Amy: There’s just one more thing that may awe and amaze and may change how we think of the dinosaur days. Get ready for this – surprise is in store! Three, two, one…yep. Dinosaurs can’t roar!

Maureen: Rumble. Grumble. Grunt. Hiss.

Amy: Yes! Dinosaurs can’t roar. Current research exists saying dinosaurs rumbled and dinosaurs hissed, but the only roars heard anytime, anywhere came from mammals like lions and tigers and bears. Roaring or not, let’s give dinos three cheers! They ruled on this planet for millions of years. We still love them all – Brontosaurus to Rex! Who knows what we’ll learn about dinosaurs next?

Maureen: I loved how the book explained that scientific thinking about Tyrannosaurus rex and other dinosaurs has changed over time, as new discoveries are made. Remember how the book said that different kinds of dinosaurs lived at different times? This set of stamps shows us two sets of dinosaurs that lived in a similar area, but were separated by 75 million years. These are both artistic scenes depicting the plants and animals from the western part of the United States during the time of dinosaurs. The picture on the top shows a scene from Colorado, 150 million years ago. The picture on the bottom shows a scene from Montana, 75 million years ago. Montana and Colorado are pretty close to each other in the US but you can see that these two sets of stamps show dinosaurs that are all different, because they lived at different times. Can you find one that looks like a Tyrannosaurus rex?

The stamp right in the middle of the scene from Montana has a dinosaur that looks a lot like a T. rex. It’s called a Daspletosaurus, which means frightful lizard, and it’s a close relative of T. rex. They are both part of a group of dinosaurs called Tyrannosaurids, but the Daspletosaurus died out about 8 million years before the T. rex came along. They sure look similar, though, don’t they? Notice the small arms, the big, muscular neck, and the sharp teeth. This dinosaur was an apex predator, at the top of the food chain, just like its relative Tyrannosaurs rex.

This stamp has the star of our show on it! Here we can see two Tyrannosaurus rexes roaming around. What do you think they’re doing? It looks to me like they might be searching for food! This is the first US postage stamp to feature a T. rex, and it was designed by John Gurche, who is well-known for his dinosaur art. The Smithsonian has used his recreations of extinct animals in the past, and you can see his sculptures of early humans at the National Museum of Natural History today.

Here are the most recent US stamps to show Tyrannosaurus rex. They came out in 2019, and they have a Smithsonian National Museum of Natural History connection too! Smithsonian curator Matthew Carrano consulted with the artist who designed the stamps, and the first day of issue ceremony was held at the National Museum of Natural History. These stamps include details that help show us how the scientific thinking about the T. rex has changed.

As Amy told us, no fossils have been found that show us a baby T. rex. But we have enough other fossil evidence that give scientists plenty of information about them. We know how big a newborn T. rex was based on the size of its egg. Here you can see the newly-hatched T. rex next to a flying insect, which helps give you an idea of how small T. rexes were when they were just starting out. Although they grew to be huge – about the size of a school bus - they started out smaller than human babies. Besides the size of the baby T. rex, what else can we observe on this stamp? Do you remember hearing that scientists now believe that T. rexes probably had feathers, even as adults? You can see that this baby T. rex is covered in small, fuzzy feathers.

This stamp depicts a young adult T. rex, but it’s not just any T. rex! This one is called “the Nation’s T. rex” and the art is based on a fossil that was discovered in 1988 in Montana. This particular fossil is one of the most important specimens ever found, and it includes the first set of T. rex arms that scientists have ever uncovered. It’s now on display at the National Museum of Natural History, in the Hall of Deep Time.

This stamp shows us the same fossil – the Nation’s T. rex – with just the bones. Scientists and artists have to imagine what dinosaurs looked like on the outside, because we don’t have many fossil records of their skin. But we can learn so much from their bones! This stamp shows an adult T. rex with a baby Triceratops. We know from the fossil record that these two types of dinosaurs lived at the same time period, just before all of the dinosaurs except birds went extinct. You might notice that the T. rex skeleton in this image is posed the same way as it is in the Hall of Fossils – that's no accident! The artist who created this artwork intentionally chose to use the same pose that is on display in the hall.

The last stamp shows what the T. rex is probably most known for – being a fierce hunter! Here we see an adult T. rex chasing a young mammal. As Amy told us, we’re not sure how much hunting T. rexes did, but the fossil record tells us that they were definitely carnivores! There are so many reasons the Tyrannosaurus rex has captured our imaginations. Who knows what scientists will find out next?

Amy: I love how we can explore scientific topics and see the changes in scientific theories with new evidence through museum objects, books, and even stamps! There’s so much more that you can learn about the Tyrannosaurus rex and other dinosaurs on the National Museum of Natural History’s website.

Maureen: Thank you so much, Amy, and thank you to our audience for joining us for Stamp Stories today. You can learn more about dinosaurs on stamps by visiting the National Postal Museum’s website. You can also learn about stamps of all different topics there. We encourage you to just keep exploring!