Tyrannosaurus rex was a fearsome creature: 12 feet tall, 40 feet long, weighing over 10,000 pounds, with razor-sharp teeth as big as bananas and a bone-crushing bite force. It would eventually become the ultimate apex predator of the Late Cretaceous period.
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But the tyrannosaurs that preceded it weren't always at the top of the food chain -- one of those myths about dinosaurs you need to stop believing. For example, recent discoveries have shown there was a dinosaur five times bigger than the tyrannosaurs of its time.
Unfortunately, this even more fearsome creature's name doesn't exactly roll trippingly off the tongue. But 90 million years ago, Ulughbegsaurus uzbekistanensis was the apex predator.
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What Is Now Known About Ulughbegsaurus
It was bipedal with tiny arms, but five times bigger than the tyrannosaurs of its time
The bone and teeth fragments that would eventually identify the apex predator of its time were first discovered nearly 40 years ago by a Russian paleontologist. But Ulughbegsaurus uzbekistanensis didn't acquire species status until 2021, as the fossil had remained largely ignored for decades in Moscow's Vernadsky State Geological Museum.
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However, sharp-eyed paleontologist Kohei Tanaka from Japan recognized the fossils' importance and, with fellow researchers from Canada and Uzbekistan, helped get the new species recognition.
The uzbekistanensis portion of the binomial nomenclature refers to where the fragments were discovered: the Bissekty rock formation in the Uzbekistan portion of the large Kyzylkum Desert, which spans three countries in Central Asia. Meanwhile, the genus Ulughbegsaurus was inspired by Ulugh Beg, a 15th-century Timurid sultan and mathematician.
The new dino has some similarities with the T. rex that would eventually replace it as the apex predator of the Late Cretaceous. It was bipedal, had tiny arms, and was a ferocious carnivore with the shark-like teeth associated with its fellow carcharodontosaurs. Its dimensions -- 26 feet long and weighing over a ton -- were no match for the later T. rex, but he towered over and terrorized the tyrannosaurs of 90 million years ago.
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Size of Ulughbegsaurus:
26 feet in length
Weight of Ulughbegsaurus:
1,000 kilograms, or 2,200 pounds
When it lived:
90 million years ago
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Comparing Ulughbegsaurus With Its Tyrannosaur Contemporaries
Tyrannosaurs 90 million years ago were much smaller than they would later become
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The scariest prehistoric creatures weren't all dinosaurs. For example, you wouldn't have wanted to meet Arthropleura, an eight-foot relative of a centipede that once roamed North America and Europe.
However, none of these creatures dominated their environment like Ulughbegsaurus uzbekistanensis.
"It would have been the largest carnivorous predator in the ecosystem at that time," Darla Zelenitsky, the University of Calgary paleontologist who contributed to its entrance into the dinosaur family, told CBC .
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This is notable and provides context for the later evolution of T. rex as an apex predator. One of the things paleontologists have discovered is that tyrannosaurs only evolved to become bigger in places where there was no prey competition from larger dinosaurs. So once carcharodontosaurs like Ulughbegsauris went extinct, the time was ripe for the development of massive tyrannosaurs like T. rex.
In Central Asia 90 million years ago, Ulughbegsaurus was clearly the apex predator relative to the much smaller tyrannosaur Timurlengia, which weighed only about 375 pounds. Ulughbegsaurus was two times longer and more than five times heavier than Timurlengia, whose weight was roughly equivalent to a large modern harbor seal.
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When Did T. Rex Overtake Ulughbegsaurus as the apex predator?
About 23 million years after Ulughbegsaurus went extinct
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The timeline of dinosaurs is still being pieced together from the fossil record. Gigantic dinosaur footprints dating back 166 million years ago were recently discovered in England. Fossils recently uncovered in Brazil are older still and are estimated to be about 233 million years old. Nor were these the oldest creatures, as the fossilized skin of a beast millions of years older than dinosaurs recently made clear.
Ulughbegsaurus' time at the top of the food chain was rather brief, at least by the standards of geological time. Carcharodontosaurs went extinct about 90 million years ago for uncertain reasons. But rising sea levels and habitat loss associated with climate change were likely responsible. Climate change, it should be noted, may also have led to dinosaurs' dominance on Earth in the first place.
"This window of the dinosaur fossil record is pretty murky," Zelenitsky noted, per CBC . "When you've got a window of time that's very poorly known for fossils, you're always just trying to fill in gaps. And this is one more gap that we were able to fill in because this is the latest occurrence of one of these shark-tooth dinosaurs."
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T. rex took over as the apex predator about 67 million years ago, but its reign was too brief, as an asteroid hit the earth 66 million years ago, ending the age of the dinosaurs.