Weird Mongolian Dinosaur Wielded ‘Big, Sharp and Nasty’ Claws

 A life reconstruction of the Cretaceous dinosaur Duonychus tsogtbaatari, whose fossils were unearthed in Mongolia, is seen in this illustration obtained by Reuters on March 25, 2025. (Masato Hattori/Handout via Reuters)
A life reconstruction of the Cretaceous dinosaur Duonychus tsogtbaatari, whose fossils were unearthed in Mongolia, is seen in this illustration obtained by Reuters on March 25, 2025. (Masato Hattori/Handout via Reuters)
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Weird Mongolian Dinosaur Wielded ‘Big, Sharp and Nasty’ Claws

 A life reconstruction of the Cretaceous dinosaur Duonychus tsogtbaatari, whose fossils were unearthed in Mongolia, is seen in this illustration obtained by Reuters on March 25, 2025. (Masato Hattori/Handout via Reuters)
A life reconstruction of the Cretaceous dinosaur Duonychus tsogtbaatari, whose fossils were unearthed in Mongolia, is seen in this illustration obtained by Reuters on March 25, 2025. (Masato Hattori/Handout via Reuters)

Fossils unearthed during construction of a water pipeline in the Gobi Desert of Mongolia have revealed one of the oddest members of a rather strange group of dinosaurs, a creature whose two-fingered hands sport a pair of menacing curved claws.

The dinosaur, named Duonychus tsogtbaatari, measured about 10 feet (3 meters) long, weighed approximately 575 pounds (260 kg) and lived roughly 90 to 95 million years ago during the Cretaceous Period, researchers said. Its claws measured about a foot (30 cm) long.

Duonychus was a medium-sized member of a group of awkward-looking dinosaurs called therizinosaurs, which were known for having a rotund torso, long neck, small head, bipedal stance, feathers on the body and massive claws on the hands.

While they were part of the dinosaur clade called theropods that included all the meat-eaters such as Tyrannosaurus and Spinosaurus, therizinosaurs preferred plants on their menu.

Therizinosaurs, which inhabited Asia and North America, are distinguished by their large claws. Until now, every known therizinosaur had three clawed fingers. But Duonychus possessed one fewer, making it fitting that its name means "two claw."

"Therizinosaurs are some of the weirdest dinosaurs ever. They were theropods - so, related to meat-eaters - but they looked like giant feathered sloths," said paleontologist Yoshitsugu Kobayashi of Hokkaido University Museum in Japan, lead author of the research published on Tuesday in the journal iScience.

"Duonychus takes that weirdness even further. It had this short, two-fingered hand with claws like a raptor (swift meat-eating dinosaurs), but it used them to eat plants," Kobayashi said.

The researchers said this Duonychus individual was not fully grown. It roamed a semi-arid environment with river channels alongside other therizinosaurs, armored dinosaurs, horned dinosaurs, duck-billed dinosaurs and a smaller forerunner of Tyrannosaurus called Alectrosaurus.

While the skeleton recovered was incomplete - for instance, missing its skull and legs - the arms and hands were well-preserved.

One of the claws retained its outer covering - a sheath of keratin, the same material as in our fingernails - rather than just the underlying bone. The keratin sheath added more than 40% to the claw's length.

"These were big, sharp and nasty claws," said paleontologist and study co-author Darla Zelenitsky of the University of Calgary in Canada.

"That's incredibly rare," Kobayashi said of the keratin fossilization, "and it gives us an extraordinary window into how these dinosaurs actually used their hands in life. The hands are beautifully preserved and show a ton of detail, including fused wrist bones, stiff joints and the two massive claws."

The claws may have served multiple functions, though primarily used for grabbing and pulling down branches to feed on leaves. "They could have used the claws for other purposes as well, perhaps for grappling, defense, digging and maybe even recognizing one's own species - 'Hey, look at me. I also have only two fingers,'" Zelenitsky said.

Duonychus is an example of digit reduction - losing fingers or toes through evolution. The first land vertebrates had eight digits. The earliest dinosaurs had hands with five fingers, just as people do, but many dinosaur lineages experienced digit reduction over time.

The discovery of Duonychus means there are now no fewer than five lineages of theropods known to have independently evolved just two fingers on each hand. The most famous of these was T. rex, a member of the group called tyrannosaurs whose puny arms were way out of proportion with its enormous head and torso.

So why would fewer fingers be beneficial?

"With dinosaurs that grasped vegetation during foraging, one would think more fingers would be better. That was obviously not the case with Duonychus, as its hand construction with two fingers seemed to suit it just fine. I suspect it may have had a specialized feeding behavior or food source," Zelenitsky said.

"Tyrannosaurs were hypercarnivorous beasts with massive skulls and jaws designed for seizing and killing prey," Zelenitsky added. "For them, the fingers and arms were probably reduced because they were pretty useless compared to their skull."



Cutting Off Rhinos' Horns is a Contentious Last Resort to Stop Poaching. New Study Found it Works

A de-horned rhino grazes in South Africa's Pilanesberg National Park, Feb. 25, 2025. (AP Photo/Jerome Delay)
A de-horned rhino grazes in South Africa's Pilanesberg National Park, Feb. 25, 2025. (AP Photo/Jerome Delay)
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Cutting Off Rhinos' Horns is a Contentious Last Resort to Stop Poaching. New Study Found it Works

A de-horned rhino grazes in South Africa's Pilanesberg National Park, Feb. 25, 2025. (AP Photo/Jerome Delay)
A de-horned rhino grazes in South Africa's Pilanesberg National Park, Feb. 25, 2025. (AP Photo/Jerome Delay)

Cutting off the horns of sedated rhinos with a chainsaw has been viewed by wildlife conservationists in Africa for more than 30 years as a necessary evil to save the iconic endangered species from poaching.

They hoped the drastic action was working, but evidence was scarce.

Now, a study published Thursday in the academic journal Science has found that dehorning rhinos has led to a large reduction in poaching in game reserves in and around the Kruger National Park in northern South Africa — an area that's home to 25% of the world's rhinos and is especially vulnerable to poaching.

The results of the seven-year study that ended in 2023 are seen as long-awaited evidence that removing rhinos' horns — which needs to be done every one to two years because they grow back — helps them survive, even if the animals lose part of their makeup.

Consistently reduced poaching The conclusions seem obvious. Lucrative illegal markets in parts of southeast Asia and China crave rhino horns for use in traditional medicines, and removing the rhinos' horns take away what poachers are after.

But Tim Kuiper, a biodiversity scientist at South Africa's Nelson Mandela University and the lead author of the study, said it was new to have long-term data from multiple sites on dehorning rhinos. He said the study, conducted between January 2017 and December 2023, focused on 11 reserves in the Kruger area and compared data from eight that dehorned their rhinos against the three that didn't.

It also analyzed data from the reserves before and after they dehorned their rhinos.

The study showed that dehorning consistently reduced poaching, Kuiper said. It found that the dehorning of more than 2,000 rhinos resulted in a 78% reduction in poaching in those eight reserves, providing some confirmation that such an invasive intervention was worth it.

“It is a big part of what a rhino is, having a horn,” The Associated Press quoted Kuiper as saying. “So having to remove it is kind of a necessary evil, if I can put it that way. But it’s very effective. There’s no doubt it saved hundreds of rhinos' lives.”

South Africa has the largest numbers of black and white rhinos. Namibia, Zimbabwe and Kenya also have significant populations. There are around 17,500 white rhinos and 6,500 black rhinos left in the world, with black rhino numbers reduced from 70,000 in 1970 to less than 2,500 by the time poaching reached a crisis point in the mid-1990s, according to the Save the Rhino organization.

Dehorning was not always accepted Dehorning rhinos started in southern Africa as early as 1989. It has not been accepted without question.

There has been opposition from animal rights activists but also questions from conservationists over what impact it has on a rhino's wellbeing, and what a future might look like with more hornless rhinos.

Vanessa Duthe, a rhino researcher in South Africa not involved in the study, said rhinos use their horns to defend themselves against predators, to compete for territory and, in the case of black rhinos, to look for food. There is also evidence that dehorned rhinos adjust their movements to live in smaller ranges, she said.

She said conservationists don't know the full impacts of dehorning, but research had found it had no adverse effect on rhinos' breeding rates or mortality rates.

“What we do know is that the benefits of dehorning by far outweigh any ecological cost that we’re aware of today,” Duthe said. She said dehorning a rhino now takes around 10 minutes and the process causes minimum distress.

Blindfolds and earmuffs are put on sedated rhinos during dehorning, which also provides an opportunity to microchip rhinos and collect samples that aid research.

Only one part of the battle Conservationists agree that dehorning alone will not end rhino poaching and Kuiper said he saw it as a short-to-mid-term solution.

Other efforts like more effective law enforcement and better support for game rangers on the frontline are key.

While South Africa has helped pull rhinos back from the threat of extinction, more than 400 rhinos a year are still killed by poachers in the country.

The dehorning study was a collaboration between scientists from three South African universities, Oxford University in England and game reserve managers and rangers. It also involved the South African National Parks department, the World Wildlife Fund and the Rhino Recovery Fund.