Two-fingered dinosaur discovered in Mongolia with help of N.M. researcher

Yahoo

31-03-2025

What has two fingers per hand and just got discovered by an international research team in Mongolia?
This guy: Duonychus tsogtbaatari.
A new species of therizinosaurus has been discovered in Mongolia. Paleontologist Anthony Fiorillo, the executive director of the New Mexico Museum of Natural History and Science, was part of the research team.
The specimen was discovered at a construction site in a small village near the Chinese border. Spine segments, a humerus and most significantly, two arms, were uncovered.
'This discovery shows us how much more there is to be discovered, that there is so much more biodiversity out there to be found in the fossil record,' Fiorillo said. 'I can't wait for the next person to find the next cool thing.'
It was the two preserved arms that indicated the specimen was the member of an undiscovered species of therizinosaurus. Each arm has two fingers.
'On both arms, instead of the more typical three fingers, this one has two fingers,' Fiorillo said. 'That in itself is very unique within this group of dinosaurs called therizinosaurus.'
Duonychus tsogtbaatari is believed to have lived 90 million years ago, weighing in at almost 600 pounds and standing several meters tall. Therazinosaurus in general had an 'ungainly' body plan, Fiorillo said.
'They have long, longish necks, longish tails, a potbelly, and then these wickedly developed claws,' Fiorillo said. 'Many therizinosaurs had very long, somewhat straight claws.'
Those lethal claws were fictionalized in Jurassic World: Dominion, when a toothy rival is shish-kebabed on a therizinosaur's three-fingered hands.
The specimen discovered in Mongolia, however, has sharply curved, sloth-like claws. When Duonychus tsogtbaatari lived, in what is now the Gobi Desert, it would have looked significantly different. Although there are gaps in the fossil plant record in the Gobi, it was likely a warmer and more humid climate.
The authors of the paper posit the scythe-like claws were used to hook and bring vegetation to the dinosaur's mouth. Duonychus tsogtbaatari largely ate plants.
The two-fingered arm raises questions as well.
Several strains of theropods, a group of bipedal dinosaurs including Tyrannosaurus rex, independently evolved to have fewer fingers on each arm. Why? That remains to be seen, Fiorillo said.
'Beyond a broad statement that there's something driving evolution for, if you will, an increased efficiency of digit reduction, what you really like about a study is when it raises additional questions,' Fiorillo said. 'That is certainly one of the questions: Why is this going on, and why is it happening across multiple groups? And we don't have a real good answer for that yet.'
The lead author, Hokkaido University paleontologist Yoshitsugi Kobayashi, an expert in Mongolian dinosaurs, was a student of Fiorillo's. Another author on the paper, Tsogtbaatar Chinzorig with the University of North Carolina and the Mongolian Academy of Sciences, was Kobayashi's student. Duonychus tsogtbaatari is named after his father.
But that's not the only link between the Land of Enchantment and the new species. Fragmented fossils of therizinosaurs have been found in the Zuni Basin near the New Mexico/Arizona border.
'It's reasonable to suspect there may be more than one kind found here,' Fiorillo said. 'The great thing about paleontology is you realize how the world is connected.'