They find trace fossils in the deep sea from 130 million years ago

2023-09-05 11:36:14

Fish had already conquered the deep sea 130 million years ago, in the lower cretaceousaccording to tfossil races found in the northern Apennines, which advances their appearance in those areas by about 80 million years.

Until now, deep-sea fish fossils dated back 50 million years. Magazine PNAS publishes a study, with Spanish participation, on the existence of fossilized traces left by various types of fish when they fed or moved.

The research is based on fossil or ichnofossil traces, not on direct bodily remains of the fish (such as bones, teeth or scales), they explain to Efe Waiting for Belausteguifrom the University of Barcelona, ​​and Fernando Muniz from the University of Seville, both signatories of the study.

These “footprints” represent the earliest evidence of vertebrates living at the bottom of the sea, according to the team of researchers.

The ichnofossils are interpreted as different types of traces, mainly feeding and locomotion, left “most likely by different species of fish in the bottom sediments of a deep marine environment,” they point out.

These fossilized “footprints” represent the earliest evidence of vertebrates living at the bottom of the sea, according to the team of researchers, led by Andrea Bauconfrom the University of Studies of Genoa (Italy).

Limestones of the northern Apennines

The fossils are preserved in limestone from the northern Apennines, where abyssal plain deposits are preserved from the Tethys Ocean, which existed between the ancient continents of Gondwana and Laurasia.

The traces found come from a toothless neoteleost, from a fish similar to a chimera and a possible third fish with a large caudal fin.

The team identified trace fossils, in the form of holes and groovesand proposes that they could have been produced by three different species of fish.

The first a toothless neoteleost, the second a fish similar to a chimera -which would have generated two different types of feeding traces- and a possible third fish with a large caudal fin that would have left the mark identified as locomotion, specify Muñiz and Belaustegui. .

Comparison with current analogues

One of the tools of the ichnology it is based on comparison with current analogues. The more information there is about the traces generated by different types of organisms in their interaction with different types of substrates, the more resources exist to interpret ichnofossils.

In this case, 130 million years ago there is already evidence of the existence of different types of fish with similar anatomical features to those currently observed and that could have left traces similar to those we can see today.

For this research, the current traces were studied in various locations in Italy, in the Piedras River estuary (Huelva) and with underwater photographs at a depth of 1,544 meters in the Kermadec Trench (Pacific Ocean).

The Lower Cretaceous abyssal plains already presented a modern-type deep-sea ecosystem with multispecies aggregations of fish.

Muñiz and Belaustegui are ichnologists and their work in this study has focused on the identification and interpretation of these fossil traces. The results suggest that vertebrates colonized the deep sea in the Early Cretaceous and that this transition may have been due to increased food sources rather than a change in deep-sea oxygen levels.

Furthermore, they indicate that the Lower Cretaceous abyssal plains already presented a modern-type deep-sea ecosystem characterized by multispecies aggregations of fish.

Rights: Creative Commons.