The rock slab presented contains the most ancient indications of vertebrates in deep-sea ecosystems. It shows depressions and tracks made by fish during their feeding activities in the Early Cretaceous period. These saucer-like features have a diameter of approximately 4 cm. Credit: Andrea Baucon.
An international team of researchers, which includes scholars from the Faculty of Sciences of the University of Lisbon, Portugal, has made an unprecedented discovery concerning the missing link in evolutionary history, found in rocks dating back 130 million years.
Although vertebrates have been prominent in contemporary ecosystems of the deep sea, no fossil records had previously indicated the existence of deep-sea fish older than 50 million years. This recent excavation has revealed incredibly scarce fossils that stand as the oldest evidence of vertebrates in deep-sea environments, extending our understanding of deep-sea colonization by a remarkable 80 million years.
The research has been published in the esteemed journal, Proceedings of the National Academy of Sciences.
Andrea Baucon, the study’s lead paleontologist and a researcher at the University of Genova, Italy, expressed his disbelief upon discovering the fossils near NW Apennines, in the regions of Piacenza, Modena, and Livorno, Italy.
The fossils are astounding due to their antiquity, predating any other known deep-sea fish evidence by millions of years. Originating from the Early Cretaceous period, the new fossils reveal fish activities at depths of thousands of meters during an age of dinosaurs, elaborates Andrea Baucon.
The fossils are atypical and infrequent, comprising basin-like indentations created by feeding fish of antiquity and winding paths left by the tail of swimming fish, marking the mud of the ocean floor. These trace fossils don’t include body fossils like bones but document ancient behavioral patterns. Therefore, these fossils from the Apennines signify a crucial milestone, representing the point where fishes ventured from continental shelves to adapt to challenging new environments.
In the prehistoric depths of the Tethys Ocean—a precursor to today’s Mediterranean Sea—these primordial deep-sea fishes encountered extreme conditions including absolute darkness, frigid temperatures, and significant pressure differentials, testing the very limits of survival.
Adapting to such harsh conditions required evolutionary changes as pivotal as those that enabled terrestrial and aerial colonization, like the development of wings and limbs.
Not only are these fossils the earliest evidence of deep-sea fishes, but they also represent the most ancient known deep-sea vertebrates. The evolution of vertebrates has been characterized by transitions between various habitats—from shallow marine origins to terrestrial, aerial, and deep-sea domains. Deep-sea colonization is the least understood among these due to the sparse fossil record linked with such environments.
Carlos Neto de Carvalho, a researcher at Instituto Dom Luiz, Faculty of Sciences of the University of Lisbon, notes that the new findings illuminate an otherwise enigmatic chapter in Earth’s biological history.
The fossils compel scientists to reevaluate what may have catalyzed the deep-sea colonization by vertebrates. The study suggests that an unparalleled influx of organic matter between the Late Jurassic and Early Cretaceous periods likely attracted bottom-dwelling invertebrates, which in turn attracted fish.
Modern ocean depths were investigated to understand these prehistoric behavioral patterns, involving studies on chimeras or ‘ghost sharks’ in their natural habitats in the Pacific Ocean.
The new fossils resemble structures created by current fish species that feed by scratching the seafloor or drawing out prey through suction, linking them to the Neoteleostei group, which includes contemporary jellynose and lizard fishes.
Contrary to general belief, deep-sea sediments are rich in fossilized remains, albeit mostly of smaller planktonic organisms, notes Mário Cachão, co-author and researcher at Instituto Dom Luiz, University of Lisbon.
The discovery may represent a significant milestone in the evolutionary history of modern deep-sea vertebrate diversity. The Apennine fossils serve as the foundational roots of today’s deep-sea ecosystems and indicate a critical habitat transition in the oceanic annals. “This groundbreaking discovery offers essential insights into the earliest phases of vertebrate evolution in the deep sea, with far-reaching implications for both Earth and Life Sciences,” concludes Andrea Baucon.
Reference: The study involved collaboration from scholars associated with academic institutions from Italy, Portugal, England, Spain, Australia, and Scotland and was published on 5th September 2023 in the Proceedings of the National Academy of Sciences. DOI: 10.1073/pnas.2306164120.
Table of Contents
Frequently Asked Questions (FAQs) about deep-sea vertebrates
What is the significance of the newly discovered fossils?
The newly discovered fossils represent the earliest known evidence of deep-sea vertebrates, dating back to 130 million years ago. This extends our understanding of when vertebrates first colonized deep-sea environments by a staggering 80 million years.
Who led the research on these ancient deep-sea vertebrates?
The research was led by paleontologist Andrea Baucon, a researcher at the University of Genova in Italy. The study also involved an international collaboration with institutions from multiple countries.
Where were these ancient deep-sea vertebrate fossils found?
The fossils were discovered in the NW Apennines, near the Italian cities of Piacenza, Modena, and Livorno.
What do the fossils consist of?
The fossils consist of bowl-shaped excavations produced by ancient feeding fishes and the sinuous trails formed by the tails of swimming fishes. These are trace fossils that record ancient behavior, rather than body fossils like bones.
How do these findings contribute to our understanding of vertebrate evolution?
The fossils mark a critical point in the timeline of vertebrate evolution, being the earliest evidence of vertebrates in the deep sea. They offer insight into how vertebrates transitioned from shallow marine origins to colonize new, harsh environments.
What journal published the research findings?
The findings were published in the journal Proceedings of the National Academy of Sciences.
What environmental conditions did these ancient deep-sea fishes face?
The earliest deep-sea fishes faced extreme environmental conditions, such as total darkness, near-freezing temperatures, and enormous pressures.
What methodologies were used in the study?
Researchers used photogrammetry to deliver a photo-textured height map of fossil feeding pits and trails. They also studied the behavior of modern fishes to understand the behaviors associated with the earliest fossils of deep-sea vertebrates.
Who collaborated on this research?
The study involved a collaboration of researchers affiliated to scientific institutions from Italy, Portugal, England, Spain, Australia, and Scotland.
What implications do these findings have for Earth and Life Sciences?
The findings have profound implications for both Earth and Life Sciences, as they reassess the mode and tempo of vertebrate colonization of the deep sea and offer fundamental clues about the early stages of vertebrate evolution in these environments.
More about deep-sea vertebrates
- Proceedings of the National Academy of Sciences
- University of Genova Research Department
- Faculty of Sciences of the University of Lisbon
- Deep-Sea Vertebrate Evolution
- Photogrammetry in Paleontology
- Modern Deep-Sea Fish Behavior Study
- Deep-Sea Colonization Theories
- Overview of the Tethys Ocean
- The Apennines Geological Information
- Trace Fossils: An Introduction
10 comments
Absolutely mindblowing. Kudos to Andrea Baucon and the team, you guys are rewriting history books.
Andrea Baucon, you’re a rockstar. Literally, coz you study rocks and fossils haha. but seriously, this is epic.
So they used photogrammetry? Thats some next-level stuff to get all those details.
i’m not a science guy but this is cool. does it mean deep sea was populated way before we thought?
This is why I love science! Always pushing the boundaries and challenging our beliefs. Keep up the good work.
Seriously, this is big news for science and maybe also for other sectors. Climate change peeps, u listening?
Wait, they studied modern fishes too? That’s a smart move, compare the old with the new to get the full pic.
I have read the paper in PNAS. The methodology and results are rock solid. No pun intended 😉
Wow, this is huge! Never thought we’d find fossils this old. Totally changes what we knew about deep-sea life.
Isn’t it amazing how every new discovery just turns what we ‘knew’ on its head? Makes me wonder what else we got wrong.