A 10-million-year-old extinct seal from South America ate the same types of bottom-dwelling fish that modern sea lions hunt in the same region today, according to Gram Research analysis of fossilized stomach contents. This discovery suggests that ocean food webs in the South Atlantic have remained remarkably stable over millions of years, with marine predators pursuing similar hunting strategies across geological time periods.
Scientists discovered the fossilized stomach contents of an extinct seal that lived millions of years ago in South America. By studying what this ancient seal ate, researchers found that it hunted the same types of fish as modern sea lions in the same region today. This discovery shows that marine predators in the South Atlantic have been eating similar prey for millions of years, suggesting that certain ocean ecosystems have remained stable over vast stretches of time. The findings help us understand how ocean life has evolved and adapted over geological time periods.
Key Statistics
A detailed examination of a single fossil seal specimen from the Late Miocene period, approximately 10 million years ago, revealed stomach contents containing benthic and demersal fish species identical to prey hunted by modern South American sea lions in the same region today.
The extinct seal Kawas benegasorum, the only known phocine seal fossil from the Southern Hemisphere, displayed a mix of northern and southern seal characteristics, suggesting complex evolutionary relationships within the seal family that remain incompletely understood.
Fossilized stomach contents from a single Late Miocene seal specimen provide rare direct evidence of ancient marine predator diets, demonstrating that coastal, bottom-dwelling fish foraging strategies in seals originated earlier in their evolutionary history than previously documented.
The Quick Take
- What they studied: What did an extinct seal from 10 million years ago eat, and how does it compare to what modern seals eat today?
- Who participated: One fossilized skeleton of Kawas benegasorum, an extinct seal species from the Late Miocene period (about 10 million years ago) found in Argentina, plus comparison data from modern South American sea lions living in the same region today.
- Key finding: The ancient seal’s stomach contained bones and remains of fish that lived on the ocean floor near the coast, the exact same type of prey that modern sea lions hunt in the same waters today.
- What it means for you: This research shows that ocean ecosystems can remain remarkably stable over millions of years. Understanding how ancient marine life adapted helps scientists predict how modern ocean life might respond to environmental changes. However, this is based on a single fossil specimen, so the findings represent one snapshot in time rather than a complete picture of ancient seal behavior.
The Research Details
Researchers examined a single, well-preserved fossil skeleton of an extinct seal species called Kawas benegasorum that lived during the Late Miocene period, approximately 10 million years ago. The fossil was discovered in the Puerto Madryn Formation in Argentina and is the only known specimen of this species. Scientists used multiple research methods to understand this ancient seal: they carefully studied its bones and teeth to understand its body structure and how it was related to modern seals, and they examined the contents preserved in its stomach to determine what it ate. The researchers then compared their findings to what is known about modern sea lions living in the same South Atlantic region today. This approach allowed them to trace how marine predators and their food sources have changed (or stayed the same) over millions of years.
Studying fossilized stomach contents is extremely rare and valuable because it provides direct evidence of what ancient animals actually ate, rather than just guessing based on their teeth or bones. By comparing an ancient seal’s diet to modern seals in the same location, scientists can understand whether ocean ecosystems have remained stable or changed dramatically over geological time. This type of research helps us understand the long-term patterns of evolution and ecological relationships in marine environments, which is important for predicting how ocean life might respond to future environmental changes.
This study is based on a single fossil specimen, which is both a strength and a limitation. The strength is that having actual stomach contents preserved is exceptionally rare and provides direct evidence. The limitation is that one specimen cannot tell us about the full range of behaviors or dietary preferences of the species. The fossil is well-preserved and housed in a museum, allowing other scientists to verify the findings. The research was published in Royal Society Open Science, a peer-reviewed journal, meaning other experts reviewed the work before publication. However, readers should understand that conclusions about an entire extinct species are based on this single individual.
What the Results Show
The stomach contents of the ancient seal contained bones and remains of fish species that lived on the ocean floor and in coastal waters. These were primarily benthic and demersal fish, meaning fish that live on or near the seafloor in shallow to moderate depths. The prey species identified in the stomach are consistent with fish that would have inhabited the South Atlantic coastal region 10 million years ago. When researchers compared this ancient diet to the eating habits of modern South American sea lions living in the same region today, they found striking similarities. Modern sea lions in the area hunt the same types of bottom-dwelling, coastal fish species. This suggests that the types of fish available in these waters, and the hunting strategies of marine predators, have remained relatively consistent over millions of years. The ancient seal’s body structure showed a mix of features found in different seal groups, but overall resembled modern seals from the Southern Hemisphere more closely than Northern Hemisphere seals.
The detailed examination of the seal’s teeth and bones revealed that Kawas benegasorum had characteristics of both northern seals (phocines) and southern seals (monachines), making its exact evolutionary position somewhat unclear. The fossil shows that this seal was adapted for hunting in shallow, coastal waters rather than deep ocean environments. The presence of this seal species in South America during the Late Miocene suggests that seal diversity in the Southern Hemisphere was greater in the past than previously documented. The research also demonstrates that benthic foraging (hunting on the ocean floor) in seals occurred much earlier in their evolutionary history than previously thought.
This study adds important new information to our understanding of marine predator evolution in the Southern Hemisphere. Previous research on this fossil seal was limited and incomplete. This comprehensive re-examination provides the first detailed look at its complete skeleton, teeth, and stomach contents. The finding of dietary convergence (similar eating habits across millions of years) supports a broader scientific understanding that successful ecological strategies tend to persist when environmental conditions remain stable. The research also contributes to ongoing debates about seal evolution and how different seal groups are related to each other, though the fossil’s mixed characteristics mean scientists still have questions about its exact place in the seal family tree.
The most significant limitation is that this study is based on a single fossil specimen. One individual cannot represent an entire species or population, so we cannot be certain that all Kawas benegasorum seals ate the same diet or behaved the same way. The fossil is approximately 10 million years old, so we are looking at a single moment in time rather than understanding how this species’ diet might have changed over thousands of years. The stomach contents may not represent the seal’s typical diet but rather just what it happened to eat before it died. Identifying fish species from fossilized bones can be challenging and may not be completely accurate. The comparison to modern sea lions assumes that the ocean environment and available prey have remained similar, which may not be entirely true over such a vast time period. Finally, the evolutionary relationships of this seal species remain unclear due to its mixed characteristics, which makes it harder to understand its broader ecological role.
The Bottom Line
This research does not provide direct health or lifestyle recommendations for people. Instead, it offers insights for scientists and educators interested in marine evolution and ocean ecology. The findings support the scientific principle that understanding long-term ecological patterns helps us predict how marine ecosystems might respond to future changes. For those interested in marine conservation, this research demonstrates that certain ocean ecosystems can maintain stable characteristics over extremely long time periods, which has implications for conservation strategies. The evidence is strong for this particular fossil specimen but limited in scope due to the single-specimen nature of the study.
This research is most relevant to paleontologists (scientists who study fossils), marine biologists, evolutionary biologists, and oceanographers. It is also valuable for educators teaching about evolution, marine life, and deep time. People interested in understanding how ocean ecosystems have changed over millions of years will find this research interesting. Conservation professionals may find value in understanding long-term ecological stability patterns. General readers interested in natural history and how scientists learn about extinct animals will appreciate the detective work involved in studying fossilized stomach contents. This research is not directly applicable to medical, nutritional, or health decisions for individuals.
This research describes events that occurred 10 million years ago, so there is no timeline for personal application. For scientists, this research may influence thinking about marine ecosystem stability over the coming years as more fossils are discovered and studied. The findings are relevant to long-term conservation planning and understanding how ocean life might adapt to environmental changes over decades to centuries.
Frequently Asked Questions
What did ancient seals eat millions of years ago?
A 10-million-year-old extinct seal from Argentina had stomach contents containing bottom-dwelling fish species. These were the same types of fish that modern sea lions hunt in the same South Atlantic region today, suggesting ocean food webs have remained stable over millions of years.
How do scientists know what extinct animals ate?
Rarely, fossilized stomach contents are preserved in skeletons, providing direct evidence of diet. Scientists examine the bones and remains of prey animals found inside the fossil, then compare them to modern species to understand what the ancient animal hunted and how it survived.
Why is finding a fossil with stomach contents so important?
Fossilized stomach contents are extremely rare and valuable because they show exactly what an animal ate, rather than scientists guessing based on teeth or bones. This provides direct evidence of ancient diets and helps us understand whether ocean ecosystems have changed or remained stable over millions of years.
Can scientists determine an entire species’ diet from one fossil?
One fossil provides a snapshot of what that individual animal ate, but cannot represent an entire species’ complete dietary range. Scientists need multiple specimens across different time periods to understand how a species’ diet varied and changed over time.
How does studying ancient seals help us today?
Understanding how marine ecosystems remained stable over millions of years helps scientists predict how ocean life might respond to future environmental changes. This knowledge supports conservation strategies and helps us understand long-term patterns in nature.
Want to Apply This Research?
- Users interested in marine science could track their learning about ocean evolution by recording fossil discoveries, extinct species studied, or marine ecosystems explored. For example, logging which marine predator species they have learned about and what those species eat could create a personal database of marine food webs across time periods.
- Users could use an app to explore and document the diets of modern marine animals in their region, then compare them to historical or fossil records. This could involve photographing local fish species, researching what local seals or sea lions eat, and building a personal understanding of how ocean food webs work. Users could set reminders to visit aquariums or marine centers to learn about local marine predators and their prey.
- Long-term tracking could involve documenting changes in local marine ecosystems over time by recording fish species observed, monitoring marine predator populations if accessible, and comparing findings to historical records or scientific literature. Users could create a personal timeline of marine evolution learning, tracking which species they have studied and how their understanding of ocean ecosystems has developed.
This article describes paleontological research about an extinct animal species and does not provide medical, nutritional, or health advice for humans. The findings are based on a single fossil specimen and represent one point in time rather than comprehensive knowledge about the extinct species. Readers should consult qualified scientists, paleontologists, or marine biologists for detailed information about fossil research or marine evolution. This research does not replace professional scientific consultation or peer-reviewed literature review for academic or research purposes.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.