Huge prehistoric predatory fish had a body like an alligator

The waters of the 360-million-year-old Gondwana subcontinent were a dangerous place to swim. A murderous, bony fish the length of an adult California sea lion that preyed on freshwater rivers as a top predator. It was huge – a new discovery shows this was the largest prehistoric bony fish ever found in southern Africa.

His ferocity is reflected in his name, Hyneria udlezinye (H. udlesinje), meaning “the one who devours others” in IsiXhosa, an indigenous language widespread in southeastern South Africa, where her bones were found.

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“Imagine a fish that looks a bit like a giant alligator. About 2.5 m long but with a rounder head like the front end of a torpedo,” says Per Ahlberg, a paleontologist and zoologist at Uppsala University in Sweden PopSci. Ahlberg is co-author of a study published Feb. 22 in the journal Plus one describe the carnivore. “The small eyes are near the front of the head. In the mouth were rows of small, pointed teeth along with pairs of large fangs, up to a few inches across.”

The specimen was found around 419.2 million and 358.9 million years ago on the outskirts of Makhanda, South Africa, in the Waterloo Farm deposit, a fossil site rich in specimens from the late Devonian world. Co-author Rob Gess, a paleontologist from the Albany Museum and Rhodes University, South Africa, has been collecting samples from the site since 1985, where he discovered bones, teeth and small invertebrates, as well as weeds and plants.

“This fossil site is of global importance for understanding the biogeography of the late Devonian world because it offers us the only known window into a polar ecosystem during this crucial time span,” says Gess PopSci.

But the remains of larger things lurk there, too. H. udlesinje belongs to an extinct group of lobe-finned fish called Tristichopterids. Late in the Devonian, a branch of the Tristichopterid family evolved into a collection of giants. These giant tristichopterids may have originated in Gondwana, the ancient supercontinent, before migrating to Euramerica. That’s what the study authors found H. udlesinje is closely related to its North American cousins ​​by comparing it to specimens of Hyneria lindae found in Pennsylvania’s Catskill Formation. The authors say this supports the idea that all these giants originated in Gondwana and adds a piece to their evolutionary puzzle.

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All other fish of the Tristichopterid group were widely thought to live in the more tropical or central regions of the subcontinent, but these specimens were found south of the Paleoantarctic Circle (our Antarctic Circle) at the time. This suggests a more global distribution of the fish, from the equator down closer to the poles.

H. udlesinje was a ferocious predator that would have eaten most of the larger species of fish – including relatives of the modern coelacanth – and quadrupeds found near the site. Their body shape also suggests they were likely “lurking predators,” quietly hiding and then quickly pouncing to grab passing prey with fangs.

As terrifying as it must have been, this apex predator wasn’t entirely invulnerable. The tristichopterids, along with many other species of fish with lobe-fins and armor plates, “extinct 358.9 million years ago in the Late Devonian mass extinction event — the second of the five major global extinction events that radically altered the composition of life on Earth,” explains Gess.

Learning more about the Denovian world can help scientists better understand not only the flora and fauna that went extinct during this mass extinction, but also more about evolution and even about ourselves as humans.

“This was a particularly interesting time in the planet’s history, when life on land was only recently established and rapidly diversifying,” says Ahlberg. “Our own distant ancestors” – the earliest four-limbed animals, or tetrapods – “emerged from the waters during the Devonian.”

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