By Harry Benson 

Recently, in the Gobi Desert in Mongolia, paleontologists have found a new species of dinosaur, which they named Duonychus Tsogtbaartari, meaning simply two claws. The name Duonychus was chosen by the leading author of the study, Yoshitsugu Kobayashi, as well as Darla Zelenitsky, Anthony Fiorillo, and Tsogbaatar Chitzorig. The dinosaurs’ scientific name was carefully chosen in recognition of Paleontologist Khishigjav Tsogbaatar, who is a former director of the Institute of Paleontology at the Mongolian Academy of Science. 

The dinosaur was originally found by the Institute of Paleontology in 2012 during the making of a water pipeline in the eastern part of the Gobi Desert. The holotype, which is the first piece of the animal ever found, specimen of Duonychus wasn’t a fully grown animal. Due to this, we can only estimate the dinosaur’s fully grown size; these estimates place the dinosaur to have grown to be about 9.8 feet long. Duonychus, like its relatives, lived a herbivorous lifestyle, eating plants as its main diet. The Duonychus fossils come from the Bayanshiree Formation in the eastern Gobi Desert and date to the late Cretaceous period around 90 ~MYA (Million Years Ago). The dinosaur’s holotype included multiple vertebrae, a lot of the forelimbs, and a piece of the pelvic girdle. 

Duonychus belonged to the family Therizinosauridae, which included dinosaurs such as the more famous Therizinosaurus as well as Erlikosaurus, Segnosaurus, and more. This family generally had similar body formations, having a long neck, huge claws, and also most likely feathers. While all of the other members of the Therizinosauridae had three claws to our knowledge, Duonychus was an anomaly of sorts, having only two, as mentioned in its name. This means Duonychus is the first member of the Therizinosauridae with only two claws to have shown up in the fossil record. This drastically changes our understanding of these creatures and opens up a gateway for countless possibilities. We have found only incomplete specimens of many members of the Therizinosauridae, meaning up until now we thought that all of the members of this family would have had three claws. But now, thanks to this discovery, we have learned more about the potential claw structures of the Therizinosauridae as a whole and how they may have varied more than we previously knew. 

 Duonychus belonged to a formation known as the Bayanshiree. Many other animals are known from this formation, such as the Paraligator, Hybodus, Alchiloabator, Graliceratops, and many more. What is very interesting, though, is that within this formation resided three other named members of the Therizinosauridae family, these being Enigmosaurus, Erlikosaurus, and Sengosaurus. There have been potential Therizinosaurid eggs found there, which could also be from a Sauropod or Ornithopod, as well as fossils of unnamed Therizinosaurs, which may be fossils of already named species within the family. The fact that this many members of the family were living in the same formation provides insights into the Palaeodiversity of the formation as a whole as well as the entire history of the Therizinosauridae.

Something that all members of the Therizinosauridae, including the two clawed Dunonychus, had in common were their extremely long claws, which were curved at the tips. But what were these immensely unique claws being used for? There are many theories, but the most likely is that they were being used to pull down vegetation for them to eat. This would make the claws extremely useful for their survival. It has also been theorized that the claws of the members of the Therizinosauridae were used for combat purposes to fend off predators, although it has been shown that these claws may have been too fragile to be used effectively in combat without risk of the dinosaur harming itself.  These claws could  have been used as intimidation of sorts to scare off predators trying to attack it or potentially they could have been used if they were in a life or death scenario. Interestingly, many papers say that they could have also been used for mating purposes, akin to how many creatures today use their features to attract mates. 
The discovery of Duonychus has led to the way we look at the family of Therizinosauridae being changed forever. Finding Deinonychus has also allowed us to obtain a better glance into the environment of the Bayanshiree formation, letting us understand more about what the ecosystem was like during that time period. As well as helped us understand more about the infamous claws of the Therizinosauridae family. Duonychus is such a fantastic find of a dinosaur that will help us continue to understand what Therizinosaurids were truly like.   By maintaining an interest in the study of fossils, we can better understand our past and how it relates to our present understanding of evolutionary relationships.