The discovery of a tooth in the faeces of an ancient species of shark has allowed scientists to conclude that they were prone to cannibalism and ate their own young.

Orthacanthus sharks resided in hot swamps around the coast of today’s North America and Europe around 300 million years ago when the lands sat closer to the equator and was surrounded by hot jungles.

The research was conducted by Aodhan Ó Gogáin and his team during his masters at the University of Bristol who has now moved to Trinity College Dublin to study his PhD and continue wider research into prehistoric fish around the coast of Canada, according to a BBC report.

It was in Canada that the sample of faeces was collected. With its distinctive spiral shape the shark poop was identifiable as that of the Orthacanthus shark as well as the tooth found within it, helping Ó Gogáin to conclude that the sharks did indeed resort to eating their own young.

“These sharks have very distinctive tricuspid teeth, where they have little tusks coming up from the tooth,” stated Ó Gogáin.

The reason for this is thought to be the shark’s move into freshwater swamp regions which dangerously limited their food supply causing them to turn on their own.

“It’s possible that Orthacanthus used inland waterways as protected nurseries to rear its babies, but then consumed them as food when other resources became scarce,” says study author Howard Falcon-Lang, from the Royal Holloway University of London. 

“There’s cannibalism and then there’s specifically filial cannibalism. And that is relatively unusual. We generally find it in rather stressed ecosystems, where for whatever reason, food is running scarce. Obviously it’s evolutionarily a bad move to eat your own young unless you absolutely have to. But in these 300 million-year-old ecosystems we’re finding evidence for filial cannibalism quite commonly, based on the coprolite remains,” Falcon-Long told BBC News.

Details of the study are published in the journal Palaeontology.