Therizinosaurs inhabited the earth during the Cretaceous period. Thanks to a fossil found in marine sediments in Japan, scientists found that one of the species belonging to this family may have been equipped with knife-like claws.
Millions of years ago, the shores of today’s Asia were inhabited by a dinosaur that had knives instead of fingers. This dinosaur belonged to the therizinosaur family – two-legged and mostly herbivorous three-toed reptiles that lived during the Cretaceous period (about 145 to 66 million years ago). Recently, researchers from Japan and the United States described the youngest therizinosaur fossil found in Japan. The remainder is also the first fossil found in marine sediments in Asia.
The new species has been described as Paralitherizinosaurus japonicus.
A hook-shaped fossil containing parts of a vertebra, wrist and forefoot was discovered in 2008. It was closed in a concretion, i.e. an aggregate formed as a result of the growth of mineral layers. From the outset, researchers suspected it belonged to Therizinosaurus, but due to the lack of data for comparison, they could not conclusively confirm it. Then it was donated to the collections of the Natural History Museum in Nakagawa on the island of Hokkaido, Japan.
Thanks to the information gathered over the years, it was finally possible to classify the fossil based on the claw shape of the front part of the limb. Another team of palaeontologists had already done research.
Based on the analysis, the authors of the study concluded that the fossil, about 10 centimeters long, belonged to a therizinosaurus that lived about 80-82 million years ago. As they stated, his paws may have been equipped with very sharp claws. They were used to comb through the vegetation in search of food, and not to kill other animals. Since scientists suspected that this species of Therizinosaurus was using its claws for a specific purpose, they concluded that the specimen appeared later in the family’s lineage. The researchers reported that in early therizinosaurs, claws were not adapted to a single activity.
– This dinosaur used its claws as feeding tools, not aggression tools. He pulled shrubs and trees closer to his mouth for food, said one of the authors of the study, Anthony Fiorillo, professor at the Department of Earth Sciences. Roy M. Huffington at Southern Methodist University (SMU) in Dallas. “We believe he died on land and was washed into the sea,” he added.
“We remain cautious optimists”
According to the study, therizinosaur fossils are found all over Asia as well as North America. It is known that they have gained adaptation to life in coastal environments over time. Two more therizinosaur remains have been found in Japan, but have yet to be described.
“It is not possible to confirm how large the terizinosaurus was from this fossil alone,” Fiorillo said. Scientists, however, are convinced of its large dimensions. According to the University of California Paleontology Museum, it could resemble a hadrosaurus in size – a reptile with a “duckbill” that could reach a length of nine meters and weigh up to three tons. – The fossil is so well preserved that we could find more remains of this animal if we visited the site again. We remain cautious optimists, Fiorillo said.
Main photo source: Masato Hattori / Hokkaido University