Ankylosaurs fought each other as much as they fought T. rex, new research suggests.
Scientists have found new evidence of how armored dinosaurs used their famous tail clubs and found that they even used them for social domination.
The exceptional ankylosaur fossil Zuul crurivastator has spikes along its sides that were broken off and healed while the dinosaur was alive.
Scientists think the wounds were caused by a blow from another Zuul’s massive tail club.
They say this suggests that ankylosaurs had a complex behavior, perhaps fighting for social and territorial dominance or even engaging in a “longing” season for mates.
Dr Victoria Arbour, curator of paleontology at the Royal BC Museum and former NSERC postdoctoral fellow at the Royal Ontario Museum, said: ‘I’ve been interested in how ankylosaurs used their tail clubs for years and this is a new piece really exciting of the puzzle.
“We know that ankylosaurs could use their tail clubs to deliver very hard blows to an opponent, but most people thought they used their tail clubs to fight off predators.
“Instead, ankylosaurs like Zuul may have fought each other.”
The 76-million-year-old herbivorous dinosaur, part of the Royal Ontario Museum’s Vertebrate Fossil Collection, is named after the fictional monster “Zuul” from the 1984 film Ghostbusters.
The skull and tail were initially freed from the surrounding rock, but the body was still encased in 35,000 pounds of sandstone.
After years of work, the body was found to have retained most of the skin and bone armor throughout the back and sides.
The animal’s body was covered with bony plates of different shapes and sizes and those along the sides were particularly large and pointed.
The scientists also noted that a number of spikes near the hips on both sides of the body were missing the spikes and the bone and horny sheath healed into a more blunt shape.
According to the researchers, the pattern of these injuries is more consistent with being the result of some form of ritualized combat or jousting with tail clubs.
Due to the location of the wounds on the body, the scientists suggest that the wounds were not caused by an attacking predator such as a tyrannosaur.
The Zuul’s tail is about three meters (10 feet) long with sharp points running along its sides.
The back half of the tail was stiff, and the tip was encased in huge bony patches, creating a formidable club-like weapon.
Zuul crurivastator means “Zuul, the destroyer of shins” – this is a nod to the idea that tail clubs were used to break the legs of tyrannosaurs which walked on two legs.
While the study doesn’t refute the idea that tail sticks could have been used for self-defense against predators, it does show that they would have also worked for intra-species combat, a factor that most likely drove their evolution.
Nowadays, specialized animal weapons such as deer antlers or antelope antlers have generally evolved to be used primarily for fighting members of the same species during battles for mates or territory.
Dr David Evans, chairman of Temerty and curator of vertebrate paleontology at the Royal Ontario Museum, said: ‘The fact that the skin and armor are preserved in place is like a snapshot of what Zuul looked like when he was alive. .
“And the wounds Zuul suffered during its lifetime tell us how it may have behaved and interacted with other animals in its ancient environment.”
The study by researchers at the Royal Ontario Museum (ROM), the Royal BC Museum and the North Carolina Museum of Natural Sciences was published in the journal Biology Letters.