Largest fully preserved dinosaur claw unearthed in Mongolia's Gobi Desert
Paleontologists unearthed the fossil in Mongolia's Gobi Desert, and the find is unique because the sheath of one of the digits is intact. Made of keratin (the same material as fingernails), the sheath reveals that the claw itself was much longer than the underlying bones. It is the largest claw of its kind found fully preserved in this way, researchers say.
'It's close to a foot in size,' said paleontologist Darla Zelenitsky, an associate professor at the University of Calgary in Canada and coauthor of a study on the discovery published in the journal iScience. 'This is by far the biggest claw preserved for a dinosaur that has that keratinous sheath on it.'
The dinosaur has been given the scientific name Duonychus tsogtbaatari, in honor of Mongolian paleontologist Khishigjav Tsogtbaatar. The genus name Duonychus means two claws in Greek.
Duonychus tsogtbaatari was part of an awkward-looking group of dinosaurs known as therizinosaurs, which were part of the theropod family that includes Tyrannosaurus rex. Therizinosaurs, however, were plant-eaters or omnivores — not apex predators.
The newly discovered dinosaur stood about 10 feet (3 meters) tall and would have weighed 573 pounds (260 kilograms). It likely used its curved claws to reach vegetation, and it could have grasped branches up to 4 inches (10 centimeters) in diameter, according to the study.
As well as two claws, the paleontologists also found fossilized parts of the prehistoric creature's backbone, tail, hips, arms and legs. The fossil was discovered by staff at Mongolia's Institute of Paleontology, part of the Mongolian Academy of Sciences, several years ago, Zelenitsky said.
Besides grasping, the two-fingered hands may have been used for display or as formidable weapons when needed, Zelenitsky said.
'They weren't predators, but they could defend themselves with those claws. They were big and very sharp,' she said.
The best comparison for the distinctive digits among living animals would be the claws of a sloth, used for hanging onto tree branches, Zelenitsky added.
Hands that looked like 'barbeque tongs'
The discovery of Duonychus tsogtbaatari's claw is an 'exciting' find, said David Hone, a paleontologist and reader in zoology at Queen Mary University of London, who wasn't involved in the research.
'I've seen fragments from other specimens from the Gobi, but never a whole sheath like this. The kind of preservation here, which is common to the vast majority of dinosaur bearing formations, doesn't usually preserve keratin,' said Hone, who is the author of the 2024 book 'Uncovering Dinosaur Behavior: What They Did and How We Know.'
'So that's really important as we know there's a pretty uncertain relationship between the keratin and the underlying bone,' he added via email.
Most therizinosaurs had long claws to grab and manipulate plants, giving them 'this reputation as Edward Scissorhands dinosaurs,' said Steve Brusatte, a professor of paleontology at the University of Edinburgh, referring to the titular character in the 1990 hit movie who had large scissor blades for hands.
'But this one is unique in having only two fingers on each of its giant arms, so they really do look like oversized tongs you might use when barbequing,' Brusatte, who wasn't involved in the research, said.
Only a few groups of dinosaurs had two fingers, most famously Tyrannosaurus rex, while single-fingered dinosaurs were even rarer, Brusatte added.
'But whereas T. rex probably wasn't using its pathetic little arms for much, and definitely not for combat or subduing prey, these therizinosaurs were using them as an integral part of their feeding strategy,' he added.
Zelenitsky said the dinosaur likely had feathers as other therizinosaurs 'were covered in feathers,' adding to their 'odd-looking demeanour.'
'This is yet another example of a wonderful new dinosaur that we couldn't have dreamed ever existed if we didn't find its fossils,' Brusatte said.
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