Paleontology Newsflash: Ulughbegsaurus uzbekistanensis


Well, Calvinosaurus it ain't.

Dinosaur silhouettes modified from Freevector.com, used under Creative Commons

September 15, 2021—Ulughbegsaurus and the Myth of the Giant T. rex Nemesis


You may have noticed some startling news over the weekend—something about a monstrous new dinosaurian carnivore that made Tyrannosaurus rex look like a lap dog. News outlets as well-known as Yahoo News and People Magazine reported it, and so far I haven’t seen a retraction (though I haven’t looked terribly closely for one). They claim that this monster carnivore kept the supremacy of T. rex limited to the North American continent, ruling from Asia like the giant on top of the beanstalk. They always grow ‘em bigger in Uzbekistan, right? The story is false. I haven’t delved deeply into the game of telephone that produced this phantom ginormity, but twenty years of writing about dinosaurs leads me to suspect a very common point of confusion: the quirks of scientific terminology and the general public’s mental blocks about them. In this case, someone somewhere along the lines of communication probably mistook the generic group term “tyrannosaur” for the specific term “TyrannosaurUS rex,” did the math, and filled in the blanks with dramatic extrapolation. It’s bad journalism, and the agencies that repeated the story without fact-checking their sources need to print a retraction. Whether they do so before the story inflates their readership metrics remains to be seen. It’s not the first time it’s happened. It won’t be the last. But there’s no need for anyone to have to go along with it. The solution is simple, and I’ll cover how to avoid the pitfalls of mass media science reporting by the end of this article. First, I’d like to highlight Ulughbegsaurus a little—it doesn’t deserve the overshadowing it has gotten from the shoddy reporting of certain circles.


  • Ulughbegsaurus is founded on a maxilla—the bone of the skull that helps you keep a stiff upper lip, so to speak—and has other skull and postcranial material assigned to it. All told, the scientists who described it estimate it grew 7.5-8 meters (20-25 feet) long. That’s closer to half the length of T. rex’s average of 12.3 meters (40 feet), not the five times (200 feet—twice as long as some of the longest known sauropods) reported in scrambled news stories.

  • The Cretaceous period spanned some 80 million years, making T. rex closer to us chronologically than it was to, say, Stegosaurus. Unfortunately, books and news stories alike tend to look only at terminology when reporting dates instead of reporting numbers. Ulughbegsaurus lived 90 million years ago, nearly 25 million years older than the oldest T. rex. There’s no way these two dinosaurs affected each other ecologically; Ulughbegsaurus did NOT “keep T-rex down”—it was already a fossil on the other side of the world by the time T. rex stomped onto the scene.

  • As a member of the allosauroid carcharodontosaur family, Ulughbegsaurus would likely have played the role of apex predator in its environment. We can’t know for sure, considering how little we know of its environment, but the study describing it as a new species makes the claim based on a pattern observed in other ecologies from around the world during the first three quarters of the Cretaceous period. In Early Cretaceous Utah, the carcharodontosaurs Acrocanthosaurus, and later Siats, played the apex predator role, while tyrannosaurs like Moros kept to smaller sizes and took faster prey. It’s as though for the later Jurassic and most of the Cretaceous, tyrannosaurs preferred to play the cheetah to the allosauroid’s lion. Toward the end of the Cretaceous, something changed. The carcharodontosaurs started dying out, especially in the northern hemisphere, and the tyrannosaurs traded their speed in for the size of their allosauroid predecessors. Many paleontologists find this mysterious shift in roles fascinating, and it pops up frequently in different journal papers. The Ulughbegsaurus paper mentions this mystery prominently since the new find adds data that could help illuminate what happened back then to cause the shift.

  • The gigantic size of these animals may seem impressive enough, but it had its limitations, and collectively different lineages of large theropods—sometimes called carnosaurs—pushed that size to the limit. And the limit was about the size of T. rex. Though Giganotosaurus—a member of the Dinosaur Park’s menagerie—was infamously reported to outweigh T. rex, in truth the average sizes of these two genera and others, like Mapusaurus and Tarbosaurus, probably overlapped one another significantly. Spinosaurus likewise challenged the size records in terms of length or height, but cheated a little due to its semi-aquatic lifestyle; it also may have weighed less overall than these other carnosaurs. Ulughbegsaurus grew closer to Majungasaurus—as seen in the Stewart Museum—in length, although it likely grew much taller at the hip. Majungasaurus’ short little legs represent an extreme and exceptional adaptation to its island environment, and we have no reason to argue that Ulughbegsaurus adopted its survival strategy.

Clearly, inklings of the true story manifest themselves in the false story—yes, Ulughbegsaurus probably bullied tyrannosaurs. Yes, it grew fairly large for a carnivorous dinosaur. Yes, it probably played its part in influencing tyrannosaur evolution. So how did things go so wrong in the news stories?

Short answer: bad communication habits on both sides, some unavoidable. Long answer: as a prominent member of its taxonomic group, Tyrannosaurus rex has lent its name to that group and its various levels. The scientific terms include tyrannosaurines (less inclusive), tyrannosaurids (more inclusive) and tyrannosauroids (most inclusive), all referred to generically as “tyrannosaurs.” This diverse group includes animals as different as the crested 6-foot long Guanlong, the fuzzy 30-foot long Yutyrannus, the large and lithe Albertosaurus, and of course the Tyrant King itself. Two little letters—a mere “-us”—makes all the difference. Unfortunately, those two little letters tend to get lost when someone unfamiliar with the group, their minds possibly reeling from the enormous strings of letters that make dinosaur names so proverbially intimidating, reads through the scientific jargon. Worse yet, semantic games designed to prop up weak yet beloved pet theories actively conflate the two groups. Sometimes the scientists naming new species will take advantage of the iconic Tyrannosaurus rex name to draw attention to their discovery—Raptorex, I’m looking at you! Media outlets likewise rely too much on using T. rex as a catchy and convenient point of comparison, sometimes stretching such comparisons beyond absurdity. The general public knows more dinosaurs than Tyrannosaurus—in my experience, most people can name at least five—but the trend among modern journalists has presumed T. rex stands alone, almost a synonym of the term “dinosaur” itself.


Avoiding this pitfall, fortunately, relies on observing a few little letters at the end of most groups. Well, that and a hefty dose of skepticism anytime a news outlet throws the term “T-rex” around willy nilly. To get the differences in these suffixes straight, bear in mind that scientists classify scientists in groups with varying levels of specificity or inclusiveness. The least inclusive, most specific group is a species—in this case, the “rex” in Tyrannosaurus rex refers to its species. Most of the time, though, paleontologists refer to the nex t inclusive level, the genus—the “Tyrannosaurus” half of T. rex. Scientific names traditionally use Latin and Greek linguistic forms, and genus names tend to end in “-us,” those all-important two little letters. These rules are inconsistently applied, so there are plenty of exceptions, but it’s a good rule of thumb to look for suffixes to get your bearings on what group belongs on what level of inclusiveness. The following chart of suffixes proceeds from less inclusive (smaller) groups to more inclusive.





Again, take this as a rule of thumb rather than a set of absolutes. Evolutionary relationships are, well, relative, and so too is the terminology. However, knowing these suffixes can help out quite a bit. I would also recommend relying only on primary sources—direct descriptions written by the scientists themselves. This is not the same thing as a direct quote, since secondary sources can sometimes create new meaning with a shift in context, as seen in the strange case of Ulughbegsaurus. Scientific papers can be dry and daunting in the technical obscurities of its language to any non-scientist, but in the age of the internet they’re easy to find, the terms are easy to look up, and they’re well worth the extra time and patience. It can be wise to focus on just reading the abstract—an introduction or encapsulation of the paper usually included at the beginning—if you’re just starting out. Scientists aren’t generally wordsmiths, so scientific parlance can be a tangled cobweb of language sometimes (as if the English language weren’t already tangled enough!), but investing a little time and effort in learning careful reading habits and evaluating the quality of sources can save you a TON of trouble in the long run. Yes, scientific studies can be bone dry (har), but it sure beats the confusion churned out by writers who can’t be bothered with due diligence.


-- Jeff Bond, Education Director Tanaka, K., Anvarov, O. U. O., Zelenitsky, D. K., Ahmedshaev, A. S., & Kobayashi, Y. (2021). A new carcharodontosaurian theropod dinosaur occupies apex predator niche in the early Late Cretaceous of Uzbekistan. Royal Society Open Science, 8(9), 210923.

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