If you think today's sharks are scary then you may not want to take a look at their prehistoric predecessors. Paleontologists at the Universities of Zurich and Chicago have used CT scanning and 3D printing to illustrate how a 370-million-year-old shark that lived in Morocco used to haunt and it is nothing short of terrifying.
What the researchers discovered is that these ancient sharks called chondrichthyans could not only drop their jaw halves downward but could also at the same rotate both outward. This allowed them to better capture their prey.
“Through this rotation, the younger, larger, and sharper teeth, which usually pointed toward the inside of the mouth, were brought into an upright position. This made it easier for animals to impale their prey,” explained in a statement first author of the new study Linda Frey.
“Through an inward rotation, the teeth then pushed the prey deeper into the buccal space when the jaws closed.” How do the researchers know this?
Using computed tomography scans, the team not only reconstructed the animal's jaw, but also successfully printed it out as a 3D model capable of simulating the jaw’s mechanics. This is an unprecedented impressive achievement because cartilaginous skeletons are not that well preserved as fossils meaning researchers did not have access to enough information on the jaw's functioning for a long time.
“The excellently preserved fossil we’ve examined is a unique specimen,” says UZH paleontologist and last author of the study Christian Klug.
The researchers also believe that the newly-discovered jaw enabled the prehistoric sharks to engage in what is known as suction-feeding. “In combination with the outward movement, the opening of the jaws causes sea water to rush into the oral cavity, while closing them results in a mechanical pull that entraps and immobilizes the prey," explained Frey.
Although the researchers believe this type of jaw was important during the Paleozoic era, as increasingly frequent tooth replacement became more common over the years, the rotating jaw eventually became obsolete. The study is published in the journal Communications Biology.