Dinosaur fossils were pierced by their own kind

The fierce battle with the opponent caused Big John, the largest 3-horned dinosaur specimen ever found, to have a keyhole-shaped puncture in the frill.

One side of Big John's skull.

The war between the two animals happened more than 66 million years ago, but only recently, scientists have determined that Big John's attacker was a 3-horned dinosaur, according to research published April 7 in the journal Nature. Scientific Reports magazine. "The location, shape, and size indicate damage caused by the horns of a similar-sized tri-horned dinosaur," said study leader Ruggero D'Anastasio, professor of biological anthropology at G University. d'Annunzio in Chieti-Pescara, Italy, said.

As the name suggests, Big John is a massive dinosaur. It is 8m long with a 2m wide skull. The skeleton was discovered in the Hell Creek Formation in South Dakota in 2014, about 60% complete. The fossil sold for about $7.2 million at a Paris auction house.

Before the auction, Big John was taken to Italy, where researcher Flavio Bacchia of the fossil restoration company Zoic prepared the specimen. Bacchia noticed a puncture on the right side of Big John's frill and contacted scientists at universities in Italy to have them analyze the damage.

The wound is 20 cm long and 5 cm wide, longer than a human hand, according to D'Anastasio. Most likely it wasn't the result of a direct attack. The impact may be posterior based on the location of the lesion and the shape of the keyhole. The team tested this hypothesis in the lab, simulating the impact with a replica of a three-horned dinosaur horn, and the results helped confirm it.

However, the wound did not kill Big John immediately. It survives the damage. There were clear signs of bone healing, though Big John died before the bone had fully healed. Analyzing the healing bone around the lesion compared with the wound healing rate in today's reptiles, the researchers determined that Big John was stabbed before he died. Maybe the animal died a few months later from infection from the wound, D'Anastasio speculates.

Big John is the only horned dinosaur with a hole in its skull. According to Spencer Lucas, curator of paleontology at the New Mexico Museum of Natural History in Albuquerque, it's possible that three-horned dinosaurs lived in groups.