Zurich researchers describe fish with a huge lower jaw

The long lower jaw also gives an indication of how the fish fed and was probably used to capture live prey. University of Zurich

A Zurich research team has described the 365-million-year-old fossils of a fish with an extreme underbite. The lower jaw of the fish called Alienacanthus was twice as long as its skull, according to a study published on Wednesday.

When researchers first came across fossils of Aliencanthus in what is now Poland in the 1950s, they had difficulty categorising the two long, thin bones they had found, as study leader Christian Klug from the University of Zurich explained when asked by the Keystone-SDA news agency. They had mistaken them for strange fin spines.

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It was only with more recent finds of fossils of Aliencanthus that Klug’s researchers were able to show that the strangely shaped spines were actually the lower jaw of the fish.

Large lower jaw used for live prey

The huge lower jaw shows how early creatures specialised in different foods, said Klug. This is because the long lower jaw also gives an indication of how the fish fed. According to the study, which was published in the journal “Royal Society Open Science”, the long lower jaw was probably used to capture live prey.

Alienacanthus lived around 365 million years ago, in the so-called Devonian period, which palaeontologists also refer to as the age of fish. During this time, various groups of fish dominated the oceans: sharks, bony fish, jawless fish and armoured fish, so-called placoderms, to which Aliencanthus also belonged.

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The animals showed a wide range of body, head and jaw shapes. Alienacanthus topped the list with its unique appearance, according to Klug. According to the researcher, the development of specialised jaws enabled a broader spectrum of feeding and hunting methods.

Translated from German by DeepL/amva

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