Illustration of a sea cow being attacked by a crocodile. (Credit: Jaime Bran Sarmiento)

The remains of a prehistoric sea cow tell story of multiple predator attacks

ZURICH — Some fossils tell simple stories. But a recent discovery in Venezuela tells a more complex tale, preserving evidence of multiple predator attacks on an ancient sea cow in what amounts to a detailed snapshot of prehistoric marine life. What started as a local farmer’s observation of odd-looking rocks has become a significant window into ancient ecology.

The study, published in Journal of Vertebrate Paleontology, analyzed the fossil to uncover what happened to this fossilized sea cow millions of years ago. When paleontologists unearth fossils, they typically find only fragments that hint at how ancient animals lived. But occasionally, they strike gold. The find, located 100 kilometers away from previous fossil sites, is helping researchers understand prehistoric marine food webs in unprecedented detail.

“Today, often when we observe a predator in the wild, we find the carcass of prey, which demonstrates its function as a food source for other animals too; but fossil records of this are rarer,” says lead researcher Aldo Benites-Palomino from the University of Zurich, in a statement.

The discovery required painstaking work to uncover. A team of five people spent seven hours carefully extracting the fossil using specialized techniques with full casing protection. Subsequent laboratory preparation, particularly the delicate work of preparing and restoring the skull elements, took several months.

The ancient victim belonged to a group called Culebratherium, distant relatives of today’s manatees and dugongs. Modern sea cows are basically the cows of the sea—slow-moving vegetarians that spend their days grazing on underwater plants. Like their modern cousins, this ancient sea cow had dense, heavy bones and thick layers of fat, making them easy targets for predators.

The fossil specimen, found in rock layers from Venezuela’s Agua Clara Formation, includes parts we might think of as the animal’s head and neck region, specifically, a partial skull and 18 vertebrae. The excellent preservation of the fossil’s outer bone layer, attributed to the fine sediments in which it was embedded, allowed researchers to observe clear evidence of predation.

The scientists identified two different types of bite marks telling different parts of the story. Some marks look like round punctures with slightly rough edges, while others appear as curved gouges with deep starting points. These marks match what scientists see when modern crocodilians bite their prey. These “conspicuous” deep tooth impacts concentrated on the sea cow’s snout suggest an attempt to suffocate the prey, which is a hunting strategy still used by modern crocodiles.

The second type of damage appears as long, narrow cuts with triangular cross-sections – the telltale sign of shark bites. The discovery of a tiger shark (Galeocerdo aduncus) tooth in the sea cow’s neck region, along with scattered bite marks throughout the skeleton, indicates that sharks scavenged the remains after the crocodilian attack.

“Our previous research has identified sperm whales scavenged by several shark species, and this new research highlights the importance of sea cows within the food chain,” says Benites-Palomino.

While the fossil record contains evidence of such food chain interactions, they are usually represented by fragmentary fossils with difficult-to-interpret marks. This discovery is particularly valuable because while we know the ancient Caribbean was home to many species of sea cows, their fossils are rarely found in Venezuela. Co-author professor Marcelo R. Sanchez-Villagra, director at the Palaeontological Institute & Museum at Zurich, describes the find as “remarkable,” particularly given its unusual location.

The discovery adds to growing evidence suggesting that marine food chains millions of years ago operated similarly to those we observe today, with predators and scavengers playing distinct but interconnected roles in their ecosystems. This 15-million-year-old specimen provides a rare glimpse into these ancient ecological relationships, documented through the preserved remains of predator-prey interactions.