Rare fossil reveals ‘shinbone-destroying’ dinosaurs fought each other

Damage to the spikes on the back of a fossil Zuul crurivastator They suggest that these armored dinosaurs used their tails to fight each other, not fend off Tyrannosaurs.


December 7, 2022

Artist’s impression of Zuul crurivastator in battle

Henry Sharpe

The shin-destroyer Zuul was a living tank. The spine and tail of this dinosaur were covered with pointed armored plates and ended in a stick, which was thought to have been used to fight fierce predators like the earlier ones. Tyrannosaurus rex. But a rare meaty fossil suggests that these armored herbivores likely used their tails less to fend off. rex and more to dominate each other.

Zuul crurivastator its name comes from the evil Zuul in the 1984 movie Ghost Hunterswith crurivastator meaning “destroyer of shins”. Its fossil was discovered about ten years ago during an excavation in Montana. Gorgosaursan older cousin rex – when the excavators hit the dinosaur’s tail stick. Years later, as researchers at the Royal Ontario Museum in Toronto prepared the fossil for display, they found that some of the fossil’s spikes were damaged. Most had smooth areas indicating bone remodeling, and some had keratin growths – both signs of healing, suggestive of injury in many cases.

“ [damaged spikes] “They’re in that little gap around the hips and just on the sides of the body,” says Victoria Arbor of the Royal BC Museum in British Columbia. rex attack, he says.

“Large, predatory dinosaurs can bite hard enough to leave scratches and holes in bone,” says Arbour. However, these signs are absent in this fossil.

It is based on the fact that the damaged nails are at different stages of healing and both are in an easily accessible place. Z. of crurivastator With a wagging tail and unlikely to be fatal, researchers believe dinosaurs used their tails to fight each other for social dominance. They suspect it is similar to the way modern animals use their horns or other body parts to claim territory or mate. While the stick-like tail may be useful for self-defense, its evolution was likely driven more by sexual selection than by predation. probably driven more by sexual selection than by hunting.

The idea of ​​these dinosaurs using their tail sticks to fight rex “It has become a textbook cliché,” says Stephan Lautenschlager of the University of Birmingham in the United Kingdom. He sees this work as a prime example of how a long-held hypothesis can be overturned by new evidence. “Now that paleontologists know what to look for, the same damage may come to light in other, perhaps as yet undiscovered, fossils,” he says.

Journal reference: Biology LettersDOI: 10.1098/rsbl.2022.0404

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