Palaeontologists reconstruct shark killing cold case

Posted By Ian Randall on 18 March 2010

The skeleton of a fossilised dolphin has revealed secrets about the brutal shark attack which ended its life – 4 million years ago. The result of the forensic analysis of the species, which was killed by a now extinct shark, is published in the latest issue of Palaeontology1.

Ribs of the 4 million year old fossil dolphin, showing the marks made by the teeth of Cosmopolitodus hastalis during the attack. Photo credit - Giovanni Bianucci

The dolphin, which was about 2.8 metres (9.2 feet) long, was found in the Piedmont region of northern Italy. Based on the bite marks over the skeleton, the killer appears to have been a 4 metre (13 feet) long shark, Cosmopolitodus hastalis – a species whose teeth can be found preserved in the rock in which the specimen was uncovered.

“The skeleton lay unstudied in a museum in Torino for more than a century, but when I examined it, as part of a larger study of fossil dolphins, I noticed the bite marks on the ribs, vertebrae and jaws,” said lead author on the study, Giovanni Bianucci. He added: “Identifying the victim of the attack was the easy part – it’s an extinct species of dolphin known as Astadelphis gastaldii – working out the identity of the killer called for some serious detective work, as the only evidence to go on was the bite marks.”

Forensic studies of the pattern of the bites allowed the team to delve deeper into the attack. Bianucci reconstructs the assault:

“The deepest and clearest incisions are on the ribs of the dolphin, indicating the shark attached from below, biting into the abdomen. Caught in the powerful bite, the dolphin would have struggled, and the shark probably detached a big amount of flesh by shaking its body from side to side. The bite would have caused severe damage and intense blood loss…Then, already dead or in a state of shock, the dolphin rolled onto its back, and the shark bit again, close to the fleshy dorsal fin.”

Skeleton of the dolphin, preserved for 4 million years with the bite marks across its ribs from the shark attack the killed it. Photo credit - Giovanni Bianucci

It is very rare to find evidence of fossil behaviour – like how prehistoric sharks attack their prey.

“Studies like this are important because they give us a glimpse of the ecological interactions between organisms in prehistoric seas. Shark teeth are among the most common vertebrate remains in the fossil record, yet interpreting the details of diet and feeding behaviour of extinct sharks is extremely difficult,” said Dr Kenshu Shimada, a fossil shark expert from DePaul University.

  1. BIANUCCI, G., SORCE, B., STORAI, T., & LANDINI, W. (2010). Killing in the Pliocene: shark attack on a dolphin from Italy Palaeontology, 53 (2), 457-470 DOI: 10.1111/j.1475-4983.2010.00945.x []


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