Significant bite marks found on prehistoric sharks prove that the creatures attacked each other. Four different discoveries of now-extinct shark vertebrae revealed numerous bite marks with even teeth embedded in one of them.
It is known that sharks can prey on each other – even fetuses occasionally eat their siblings inside of the womb. This behavior has been happening for millions of years as the oldest evidence of a shark biting another dates all the way back to the Devonian Period (between 419.2 and 358.9 million years ago) when a Cladoselache shark feasted on another species as the remains were found in its stomach.
But finding actual biting evidence is another story, especially in ancient sharks as their skeletons are made of cartilage which isn’t good at fossilizing. In an email to Live Science, Victor Perez, who is an assistant curator of paleontology at the Calvert Marine Museum in Solomons, Maryland, reiterated this by noting, “Sharks have been preying upon each other for millions of years, yet these interactions are rarely reported due to the poor preservation potential of cartilage.”
In this latest evidence of ancient sharks preying upon each other off the eastern coast of the United States, the researchers analyzed three fossils that were discovered between 2002 and 2016 at Calvert Cliffs on the Maryland coast, as well as another fossil that was found in the 1980s in a phosphate mine in North Carolina. It has been determined that these four fossils belonged to a class of sharks known as chondrichthyans; however, the exact species are currently unknown.
One of the Maryland fossils still had two 1.5-inch-long teeth embedded in it, but incredibly the shark didn’t die as a result of the attack because the wound appeared to have been in the healing process. Another Maryland fossil had several bite marks from different attackers. (A picture of the fossils can be viewed here.)
All four fossils date back to the Neogene Period (between 23.03 and 2.58 million years ago). And they are incredibly significant as they are the first ever documented evidence of prehistoric shark centra (the vertebrae of the spinal column) containing bite marks. As for how the fossils were able to survive for millions of years, Perez explained, “The centra are composed of a denser calcified cartilage that preserves better than other parts of the skeleton.”
The study was published in the journal Acta Palaeontologica Polonica where it can be read in full.