A fossil discovery has shed light on a tragic day in the life of a prehistoric sea cow, providing insights into the perils faced by this now-extinct species of dugong, CNN reports.
Some 15 million years ago, this marine mammal met a gruesome fate at the hands of two predators: a crocodile and a tiger shark.
Researchers analyzing the fossil, unearthed in Venezuela, found evidence of a tiger shark’s tooth embedded in the body of the sea cow. This unique finding has allowed scientists to reconstruct the events leading to the demise of this ancient creature, which belonged to an extinct group called Culebratherium.
The study, published Thursday in the Journal of Vertebrate Paleontology, captures a moment in time that provides unique insight into how the food chain worked in the early to middle Miocene Epoch 11.6 million to 23 million years ago.
“It’s super rare to find evidence of two predators on a single specimen,” said lead study author Aldo Benites-Palomino, a doctoral student in the department of paleontology at Switzerland’s University of Zurich. “It shows why we should be exploring for fossils in tropical regions like (Venezuela).”
Anatomy of an attack
The fossilized remains — a partial skull and 13 vertebrae or backbones — revealed three types of bite marks. Their shape, depth and orientation suggested that they were made by two predators: a small- to medium-size crocodilian and a tiger shark.
The crocodile-like creature attacked first, according to the study, with deep tooth impacts in the sea cow’s snout, suggesting it tried to grasp this part of the dugong’s face to suffocate it. Two other large, curved incisions indicate that the crocodile dragged the sea cow, tearing its flesh.
Striations and slashing on the fossil suggested the croc executed a “death roll,” a spinning behavior to subdue prey that is also observed in living crocodile species.
“This type of mark is only produced by biting events in which subsequent tearing, rolling or grasping actions are executed,” the study authors noted.
Then, the sea cow was picked apart by a tiger shark, which has narrow, non-serrated teeth. Differentiating between marks of active predation and scavenging can be challenging, but according to the study, bite marks throughout the sea cow’s body and the irregular distribution along with the variation in depth suggested to researchers that it was the behavior of a scavenger such as a tiger shark.
The scientists confirmed the shark’s identity through the discovery of an isolated tooth lodged in the sea cow’s neck that belonged to an extinct species of tiger shark, Galeocerdo aduncus.
“I had to work like a forensic scientist,” Benites-Palomino recalled.
However, the study noted that given the fragmentary nature of the skeleton — it wasn’t possible to rule out other scenarios for the sea cow’s demise.
Dean Lomax, a paleontologist at the University of Bristol and University of Manchester in the UK, who did not participate in the research, expressed his agreement with the study’s findings. However, he noted the challenges in distinguishing between scavenging and active predatory behavior in the context of prehistoric marine interactions.
