150-million-year old, piranha-like specimen is earliest known flesh-eating fish
by Prof David Bellwood / Dr Martina Kölbl-Ebert 28 Oct 2018 17:41 AEDT
An international team of researchers have described a remarkable new species of fish that lived in the sea in the time of the dinosaurs in the late Jurassic about 150 million years ago.
The new species of bony fish had teeth like a piranha, which the researchers from the ARC Centre of Excellence for Coral Reef Studies (Coral CoE, Australia) and Jura-Museum Eichstätt (Germany), suggest they used as piranhas do: to bite off chunks of flesh from other fish.
As further support for that notion, the team also found the victims – other fish that had apparently been nibbled on – in the same limestone deposits in South Germany (the quarry of Ettling in the Solnhofen region) where this piranha-like fish was found.
"We have other fish from the same locality with chunks missing from their fins," said Prof David Bellwood of Coral CoE at James Cook University.
"This is an amazing parallel with modern piranhas which feed predominantly not on flesh but the fins of other fishes. It's a remarkably smart move as fins regrow, a neat renewable resource. Feed on a fish and it is dead; nibble its fins and you have food for the future."
The newly described fish is part of the world famous collections in the Jura-Museum in Eichstätt. It comes from the same limestone deposits that contained the first feathered proto-bird known as Archaeopteryx.
Careful study of the fossilized specimen's well preserved jaws revealed long, pointed teeth on the exterior of the vomer, a bone forming the roof of the mouth, and at the front of both upper and lower jaws. Additionally, there are triangular teeth with serrated cutting edges on the pre-articular bones that lie along the side of the lower jaw.
The tooth pattern and shape, jaw morphology and mechanics suggest a mouth equipped to slice flesh or fins, the international team of researchers report. The evidence points to the possibility that the early piranha-like fish may have exploited aggressive mimicry in a striking parallel to the feeding patterns of modern piranha.
"We were stunned that this fish had piranha-like teeth," Dr Martina Kölbl-Ebert of Jura-Museum Eichstätt (JME-SNSB) said.
"It comes from a group of fishes (the pycnodontids) that are famous for their crushing teeth. It is like finding a sheep with a snarl like a wolf. But what was even more remarkable is that it was from the Jurassic."
"Fish as we know them, bony fishes, just did not bite flesh of other fishes at that time. Sharks have been able to bite out chunks of flesh, but throughout history bony fishes have either fed on invertebrates or largely swallowed their prey whole. Biting chunks of flesh or fins was something that came much later," Kölbl-Ebert explained
Or, so it had seemed.
"The new findig represents the earliest record of a bony fish that bit bits off other fishes, and what's more, it was doing it in the sea," Bellwood said, noting that today's piranhas all live in freshwater.
"So when dinosaurs were walking the earth and small dinosaurs were trying to fly with the pterosaurs, fish were swimming around their feet tearing the fins or flesh off each other."
The researchers call the new find a "staggering example of evolutionary versatility and opportunism." With one of the world's best known and studied fossil deposits continuing to throw up such surprises, they intend to keep up the search for even more fascinating finds.
Paper "A Piranha-like Pycnodontiform Fish from the Late Jurassic" is available here.