An important scientific breakthrough allowed for a more precise reconstruction of the marine ecosystems that dominated Patagonia millions of years ago. Researchers from the Patagonian Institute of Geology and Paleontology (IPGP-CONICET) managed to double the known biodiversity of the Gaiman Formation in Chubut, thanks to a series of campaigns developed between 2021 and 2024.
The work was concentrated in the Bryn Gwyn area, near the town of Gaiman, where specialists identified 27 distinct taxa of fossil invertebrates. This record significantly expands the knowledge about organisms that had remained practically invisible to science until now.
Moreover, the findings provide new evidence about the environmental conditions that characterized the Early Miocene, a period when large regions of the current Patagonian steppe were covered by much warmer marine waters than those of the current South Atlantic.
A biodiversity hidden for more than a century
For decades, the Gaiman Formation was mainly recognized for its extraordinary marine vertebrate fossils, including whales, birds, and penguins. However, the smaller fauna had received little scientific attention.
Consequently, the recent investigations allowed for the discovery of a surprising diversity of marine organisms, including snails, sea urchins, crabs, brachiopods, and scaphopods, groups that had not been documented in this geological sector until now.
Additionally, the survey demonstrated that these ecosystems had a complex biological network, capable of sustaining numerous species adapted to shallow coastal and marine environments. This information helps reconstruct in greater detail the dynamics of the oceans that dominated Patagonia approximately 16 million years ago.
The discovery of a new marine species
One of the most notable results was the identification of a new species of marine snail named Buccinanops halleri.
This fossil represents the oldest known ancestor of a genus that still inhabits the coasts of Puerto Madryn and Puerto Pirámides. Thanks to this discovery, researchers can trace the origin and evolution of organisms that are part of the current biodiversity of the Patagonian Atlantic coast.
Furthermore, the new species was named in honor of geologist Miguel Haller, a scientific reference who contributed decisively to the study of the Gaiman Formation and whose work left a profound mark on Argentine geological research.
Fundamental contributions to understanding the evolution of Argentine territory
The results obtained allow connecting the natural history of Chubut with other regions of Patagonia. In fact, the fossils found present similarities with records from the Monte León formations in Santa Cruz and Chenque in southern Chubut.
Thanks to this evidence, scientists confirmed that all these areas were linked by the same marine transgression event, a phenomenon in which the rise in sea level flooded extensive continental surfaces.
Additionally, this research provides key pieces to understand the evolution of Argentine biodiversity, allowing for the reconstruction of how ecosystems responded to climatic and geological changes that occurred over millions of years. This knowledge also helps interpret the current distribution of numerous species and strengthens the conservation of the national paleontological heritage.
New challenges for Patagonian paleontology
The researchers consider that this survey represents just the beginning of a broader stage of scientific exploration.
Therefore, upcoming studies will seek to compare the records from Gaiman with those obtained in Peninsula Valdés, Río Negro, and other areas of Patagonia, with the aim of comprehensively reconstructing the ancient seas that covered southern South America.
Meanwhile, the sediments of the region continue to offer clues about still unknown organisms, reaffirming Patagonia as one of the most valuable territories on the planet for understanding the history of life and the evolution of ecosystems.
