A four-legged duck-billed dinosaur that lived 68 million years ago in the southeast of present-day Russia probably broke his wrist when he fell while standing on his hind limbs and reaching for the upper branches of trees, or while mating. This conclusion was made by Belgian, Russian and British scientists who studied the remains of the herbivorous hadrosaur Amurosaurus riabinini found near Blagoveshchensk. An article about this was published in the journal Historical Biology.
"He was standing upright, perhaps to eat, mate or for some other reason," lead author Filippo Bertozzo of the Royal Belgian Institute of Natural Sciences told New Scientist. - The bone we examined is normally very thin, smooth and graceful, but in this particular case, a huge tumor is found on it, at the very end of the wrist. We became interested in finding out what happened to this poor animal.”
Bertozzo and his colleagues used X-ray imaging technology to analyze damage to the ulna of a normally herding dinosaur—these dinosaurs moved in large herds of tens to hundreds of individuals. The studied animal was not yet out of adolescence, and its dimensions did not exceed 5 m in length and 2 m in height. Analyzing the digital image of the bone and comparing the thus obtained structure of the ulna with the corresponding areas that belonged to uninjured individuals A. Riabinini, the scientists found that the dinosaur probably fell from a vertical position, which caused a diagonal fracture at the end of the ulna. All this led to further inaccurate fusion of this area during the healing process. Judging by the degree of bone healing, the dinosaur probably limped for at least four months before dying. “The fracture is completely surrounded by a structure that protects the bone during the healing process,” said Bertozzo. - We can say for sure that this wound did not immediately kill the dinosaur, because the regeneration process was launched. These lizards were very tenacious, because it is quite difficult to walk and run with such an injury.
Bertozzo suggests that this Far Eastern hadrosaur may have received additional protection from relatives while inside the herd.
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