Battle-Scarred Ichthyosaur Jaw Found in Australia

Researchers have discovered what appear to be healed bite wounds on the fossilized lower jaw of an ichthyosaur. The findings are detailed in a forthcoming issue of the journal Acta Palaeontologica Polonica.

Ichthyosaurs were a diverse group of dolphin-like reptiles that are believed to have inhabited the oceans from 250 to 90 million years ago. They had sharp teeth, and preyed on fish and squid-like creatures.

This particular skeleton was recovered near Marree, a town in South Australia, and was identified as an approximately five-meter-long adult in the Platypterygius genus of ichthyosaurs. The fossils are believed to be 120 million years old, at which time Australia may have been much closer to the south pole than it is today, with water at freezing temperatures.

Study authors Maria Zammit at the University of Adelaide and Benjamin Kear at Uppsala University in Sweden discovered "a series of healed cuts and an associated gouge on the lower jaw" of the ichthyosaur specimen. Due to the healed appearance of the lesions, the investigators believe the wounds were not fatal.

"Based on the close spacing and non-lethal facial positioning of the wounds, they were probably not inflicted by a predator," the authors wrote in the paper’s abstract.

The authors speculate that the wounds could have been accidental or even due to social interactions with another ichthyosaur.

"Alternative explanations might include an accidental aggressive encounter with another large vertebrate, or perhaps an intraspecific interaction such as during courtship or combat over food, mates or territory," they wrote.

Skeletal injuries are rare finds in ichthyosaur fossils. "Pathological traces on ancient fossilised bones and teeth give unique insights into the lives and social behaviours of extinct animals," Kear said in a press release. "Such finds have also rarely been reported in ichthyosaurs before,” he added.