University of Calgary paleontologist Darla Zelenitsky says the species, Duonychus, as shown in this illustration, evolved to have only two claws from three, which were used for gathering vegetation. The claws were up to 30 centimetres in length. THE CANADIAN PRESS/HO-University of Calgary * MANDATORY CREDIT *

By Canadian Press

SCIENCE

Calgary paleontologist part of discovery of new dinosaur with 30-centimetre claws

Mar 25, 2025 | 2:16 PM

A University of Calgary paleontologist is part of a discovery of a new species of dinosaur with 30-centimetre-long claws found in a Mongolian desert.

Darla Zelenitsky, an associate professor in the school’s faculty of science, says the remains of the therizinosaur were found in the Gobi desert in 2012 during the construction of a water pipeline.

She said a paleontological team immediately identified there were fossils present.

“They call them the sloths of the Cretaceous period. Totally bizarre looking things,” Zelenitsky said in an interview Tuesday.

“They walked on two legs, had these rotund bodies, a long neck and a small head and then long arms with big hands and usually three fingers and three decent-sized claws.

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“It evolved to just have two fingers and two claws. The claws on this one are about a foot long…30 centimetres long. We know that because one of the claws is fully preserved.”

The specimen has been named Duonychus, which means two clawed.

Zelenitsky is one of several professors who worked on the project. The details of the find are published in Tuesday’s edition of iScience. She said it can take years or decades for dinosaur finds to be reported on.

One of the interesting things about this specimen is that one of the claws still has a 12-centimetre-long fingernail still attached, she said.

“It usually doesn’t preserve in a fossil record because it’s usually not mineralized like bone so it just rots away quickly,” she said.

Zelenitsky has co-authored over 50 different publications and was part of a team that first found evidence of feathered dinosaurs in North America.

She could only speculate what would have prompted the species to evolve from three toes to two.

“It may have specialized in a certain way. Maybe it was a certain kind of plant type or had a certain feeding behaviour so it made sense to reduce the number of fingers on the hand,” she said.

The claws would likely have been used for digging and defence.

“They would have made formidable weapons … these claws.”

Zelenitsky said this is the only specimen that’s been found, but it’s believed to have existed in both Asia and North America. She said it would weigh about 250 kilograms and stand about three metres tall from the tip of its tail to its nose.

About 50 new species of dinosaurs are discovered every year.

This report by The Canadian Press was first published March 25, 2025.