Timeless
How four letters define a dynasty
“Rarely is it safe to speak of anything as ultimate in prehistoric life, but there is little doubt that the American Museum now exhibits a skeleton of the largest flesh-eating animal that has ever lived. This is Tyrannosaurus, the tyrant lizard, a dinosaur that lived during the close of the Cretaceous period. It was one of the very last expressions of its race and, judged by size and structure, was king of its kind. An idea of its immense size can be formed from measurements of the skeleton, 47 feet in length, and, as mounted, 18 1/2 feet in height.”
As I watch and interact with the cultural zeitgeist and the media and people around me, I often find it interesting to watch people’s superlatives. That is, words that describe the absolute zenith of something, the most extreme possible expression of an idea. The subject of this essay has probably had more superlatives applied to it than any other representative of its kind. It’s no wonder then that when Barnum Brown wrote about his hallmark discovery in 1915 he couldn’t help but describe it in the most outlandish terms. Often things that are described in superlative terms are later looked back on as having been affected by recency bias. A movie or book may have been the greatest of its time but eventually other things take their place. In the case of Tyrannosaurus rex, hindsight has only made it feel closer.
T. rex is ubiquitous in fiction. It is the ultimate embodiment of the raw destructive force of the natural world. From King Kong, to The Land Before Time, to Tomb Raider, to Transformers, to Marvel Comics, to Super Mario, to dozens other features, Tyrannosaurus rex serves as the singular and most iconic representative of the entirety of Earth’s past. Few other animals can claim to come close to the recognizability and raw star-power that this animal wields. The dinosaur is almost like a celebrity in a way. If it features in a project, the people in charge of marketing can’t help but place it front and center. Sometimes it feels like people will write entire plot threads into a story just to have an excuse to use a T. rex. Its a real-life monster. Of course the Jurassic Park franchise bears some of the blame for this phenomenon, but those movies do deserve some credit for using dinosaur designs that were (for the most part) fairly accurate at the time. A few other dinosaurs can claim to have; for lack of a better term, clout. Brontosaurus, Stegosaurus, Triceratops, and Velociraptor all command a certain sway with the public, but at the end of the day, if your property has dinosaurs in it, but no T. rex or similar analogue, it feels empty. Unfortunately this often works to the detriment of those trying to highlight other areas of prehistoric life. A documentary about dinosaurs or even animals not from the Mesozoic at all feels forced to include it as a necessity, to the exclusion of other things that are just as important or interesting. It honestly gets a little bit depressing every time I see charismatic animals like T. rex get so large of a share of the spotlight when Earth’s past offers so much more.
I have a distinct memory of a series of phases I went through growing up. I took an interest in dinosaurs from a very young age, and its almost taken as a given that Tyrannosaurus is everyone’s favorite. For a while, that’s easy to accept as a kid, but as you grow older and get more knowledgeable, things change. As you learn more and more names with more and more variety, T. rex starts to fade into the background. Its easy to forget about where nearly every dinosaur nerd gets their start. It almost feels like an old favorite toy (which in some cases it literally was) that you play with for a while, but eventually something new and shiny comes along and you move on. Its an easy point of pride to have a favorite dinosaur that no one else has heard of. It makes you feel smart, or at least that’s what it did for me at times. If you can think of an obscure or bizarre theropod, it was probably my favorite at some point growing up (except Monolophosaurus, iykyk). But as I grew into adulthood, I slowly began to change my views. Though T. rex never became my favorite again, I have learned a respect and love for the king of the dinosaurs, and I’d like to take the remaining space of this essay to remind us all what exactly it is we’re dealing with.
The superfamily Tyrannosauroidae first appears in the Jurassic period, and includes all of T. rex’s relatives. Genus like Kileskus, Guanlong, Stokesosaurus, and Juratyrant appear across several continents as small to mid-sized carnivores several of which possessed ornate head crests giving them a unique appearance. As the Jurassic became the Cretaceous, there is a period where few Tyrannosauroid fossils are known, but from how they end up, we can guess what they were doing. In the Late Cretaceous, they grew in size and began to develop the hallmark features they would become known for: long legs, thick, pointed teeth, and a deep, dense, strong skull. They diversified into a few subfamilies like the Alioramini, the Albertosaurinae, and the Daspletosaurini, but Asia and North America saw the most striking examples: the Tyrannosaurinae, and at this point they were taking over. The tyrant dinosaurs by the end of the Cretaceous were the dominant large carnivores over the whole of the Northern Hemisphere, and it was at this stage that our subject finally made their appearance.
Ursus maritimus is the largest terrestrial carnivore alive today. It is also known as the polar bear. These bears can reach a mass of 800 kg, can stand 3 meters tall when on their hind legs, and are the undisputed top predators of the lands in and around the arctic circle. The largest fossil mammalian predator is also a bear, called Arctotherium angustidens. The estimated body mass for this bear ranges from 900 to 1,800 kg, making the largest individuals more than twice the mass of the average polar bear, and it very well could have stood at a height of 4 meters. The largest non-dinosaur terrestrial predator to have ever lived is currently believed to be an animal called Fasolasuchus. Fasolasuchus belongs to an informal family called the rauisuchians. This theorized family includes several large terrestrial predatory Pseudosuchians (close relatives of crocodiles) that appeared in the Triassic period, but due to the fragmentary and scattered nature of the remains, formally codifying the family into common acceptance has proven exceedingly difficult. Estimates for the mass of Fasolasuchus aren’t possible with the current data, but it was estimated to be 8 to 10 meters long at its maximum, rivaling many predatory dinosaurs. Tyrannosaurus rex stands at around 12.4 meters long at the maximum, and is estimated to weigh in around 8.5 metric tons. It and dinosaurs like it stand above the rest and claim the title of largest terrestrial carnivore the Earth has ever known.
Tyrannosaurus claims further notoriety through its place in dinosaur science. T. rex is one of the most well studied dinosaurs of all time. There are more than 20 complete skeletons assigned to Tyrannosaurus. This, combined with the high general interest of the public has resulted in a massive body of research on the animal. As a result, Tyrannosaurus often serves as a testing ground for new techniques and methods of study. Estimates for its bite force are frankly, all over the place. But they all agree on one thing: the number is massive, quite possible exceeding that of the great white shark and saltwater crocodile, the greatest biters of today. Simply examining the skull tells us much about what kind of forces its head was designed to endure. The bones of the skull are thick and robust. Its teeth are more cone-shaped and pointed than other theropods; designed to puncture and crush, not just to cut. The animals it lived with and would likely have hunted included Triceratops and Ankylosaurus which are some of the most heavily defended animals in Earth’s history. It also lived among Hadrosaurs like Edmontosaurus which grew to similar sizes and likely lived in herds, which makes them similarly dangerous despite their lack of specialized defensive weaponry. T. rex’s arms have been the subject of numerous jokes since its discovery, and scientists still disagree over their exact use. Its a feature that only shows in the later, larger, and more derived Tyrannosaurs. Theories range from using them to hold onto prey or holding onto mates, to helping them rise from the ground, but my personal favorite is perhaps the simplest one: arm muscles and neck muscles share attachment space, and in order to use a big head, you need big neck muscles. T. rex sacrificed its arms to make its head even more destructive.
There are several other animals that rival Tyrannosaurus in terms of both length and mass, and this essay not meant to demean them. Several of them are believed to have hunted the giant sauropod dinosaurs for food. But, there is something special about Tyrannosaurus rex. The ways in which it is biologically unique, its tremendous legacy in science, its place in our culture, and its charismatic name all come together to make this animal stand out. The mystique of paleontology’s ever-evolving puzzle is perfectly displayed in this animal. Our search for answers can’t help but pause and admire something that once walked the same Earth as us. Seeing it is so catastrophically different from any experience known to us that it shocks us into wonder. And yet, there is so much left to be known. That is the paradoxical nature of science. The more we uncover and detail into writing, the more questions arise. We are always seeking the next limit; the next superlative. T. rex’s ability to stand the test of continued scrutiny and maintain its place as among the most notable and charismatic animals in paleontology has made it well and truly timeless, and I for one wouldn’t have it any other way.
Sources Used:
Brown, Barnum. “Tyrannosaurus, a cretaceous carnivorous dinosaur.” Scientific American, vol. 113, no. 15, 9 Oct. 1915, pp. 322–323, https://doi.org/10.1038/scientificamerican10091915-322.
Brusatte, Stephen L., et al. “Tyrannosaur paleobiology: New research on ancient exemplar organisms.” Science, vol. 329, no. 5998, 17 Sept. 2010, pp. 1481–1485, https://doi.org/10.1126/science.1193304.
Gower, David J. “Rauisuchian Archosaurs (Reptilia, Diapsida): An overview.” Neues Jahrbuch Für Geologie Und Paläontologie - Abhandlungen, vol. 218, no. 3, 29 Nov. 2000, pp. 447–488, https://doi.org/10.1127/njgpa/218/2000/447.
Hone, David W. E., and Scott Hartman. The Tyrannosaur Chronicles: The Biology of the Tyrant Dinosaurs. Zed Books, 2021.
Parrish, J. Michael, et al., editors. Tyrannosaurid Paleobiology. Indiana University Press, 2013.
Soibelzon, Leopoldo H., and Blaine W. Schubert. “The largest known bear, arctotherium angustidens, from the early pleistocene pampean region of Argentina: With a discussion of size and diet trends in bears.” Journal of Paleontology, vol. 85, no. 1, Jan. 2011, pp. 69–75, https://doi.org/10.1666/10-037.1.
“Specimens of Tyrannosaurus.” Wikipedia, Wikimedia Foundation, 15 Dec. 2024, en.wikipedia.org/wiki/Specimens_of_Tyrannosaurus.
Therrien, François, and Donald M. Henderson. “My theropod is bigger than yours … or not: Estimating body size from skull length in theropods.” Journal of Vertebrate Paleontology, vol. 27, no. 1, 12 Mar. 2007, pp. 108–115, https://doi.org/10.1671/0272-4634(2007)27[108:mtibty]2.0.co;2.