An article published in the journal “Current Biology” describes the discovery of a bony fish that lived about 150 million years ago. Named Piranhamesodon pinnatomus, it’s part of the collection of the Jura-Museum in Eichstätt and was discovered in the same limestone deposits in which Archeopteryx fossils were found, in southern Germany. The fossils discovered show that the this fish teeth were similar to those of modern piranhas and it probably used them in the same way.
Piranhamesodon pinnatomus was cataloged in the order of pycnodontiforms (Pycnodontiformes), bony fish that lived between the Triassic and the Eocene period, between 215 and 40 million years ago. Generally these fish had chisel-like teeth in the lower part of their jaws that they probably used to break their prey’s hard shells and then shred them with other round-shaped teeth. It looks like this new species discovered had different eating habits.
The study of the well-preserved jaws of the Piranhamesodon pinnatomus specimen discovered showed long, pointed teeth in various parts of its mouth and other triangular teeth. They’re very different from those of the other pycnodontiforms, so much that Martina Kölbl-Ebert of the Jura-Museum, among the authors of the research, commented that it’s like finding a sheep with a snarl like a wolf. That’s a type of tooth that’s seen today in piranhas, which instead belong to the order Characiformes.
The piranhas aren’t very big but they’re still much larger than the Piranhamesodon pinnatomus specimen, which is just over 7 centimeters long. Both species belong to the class of actinopterygians (Actinopterygii) and the one that lived in the Jurassic period is the oldest to show a teeth shape specialized in ripping meat and cutting the fins of their prey.
At the same site other fish fossils were found showing injuries to their fins compatible with the bites of Piranhamesodon pinnatomus. Again there seems to be a similarity with the behaviors of piranhas, which have the fame of devouring whole prey but actually usually eat only their fins. Those prey can survive and their fins grow back, ready for a new snack.
The discovery of Piranhamesodon pinnatomus shows an interesting case of convergent evolution in a fish that probably behaved like piranhas but during the dinosaurs’ era. The fossil specimen was discovered in a site that’s been well-known for a long time and that’s surprising but also an incentive to keep on exploring it.
