The Orthacanthus were cannibals. In fact, when hunger was pressing, these sharks, which inhabited the river and marshy areas near the ocean that surrounded the supercontinent Pangea, devoured the young. The proof is found in the coprolites of an adult specimen. Those fossil droppings, discovered in Canada’s Minto coal basin, contain the teeth of younger ones . The feces, which are easily identified by experts due to the peculiar shape of the rectum of these animals, are, so to speak, full of them.
In a study published in the journal Palaeontology , the ecologist Aodhán Ó Gogáin, from the Department of Geology at Trinity College Dublin, who made the discovery, points out that Orthacanthus habitually fed on other fish and amphibians. As indicated, it is the first time that evidence of this behavior, known as filial cannibalism, has been found in these sharks .
The paleontologist Howard Falcon-Lang, from the University of London, co-author of the essay, points out that although it is not possible to know the causes, it is known that in the Carboniferous certain species of marine fish migrated towards the coastal marshy areas. For Falcon-Lang, it is possible that this animal chose a channel that ran further inland precisely to raise and protect its young and that it was forced to eat them when other sources of food disappeared.
The Orthacanthus , which had a very elongated dorsal fin, which gave them an appearance similar to that of eels , were the super predators in that environment, in what is now Europe and North America. They had two rows of different teeth, some serrated and others flatter, and were around ten feet long. According to Ó Gogáin, “in a way, they must have resembled bull sharks, which can go up freshwater courses from the sea to return to it later. It would be an unusual evolutionary adaptation that would have played a key role in the colonization of other aquatic environments ”. However, Orthacanthus are believed to have become extinct 225 million years ago.
Image: Ghedoghedo via Wikimedia / CC
