A Hidden Fossil Tooth Reveals How a Giant Predatory Fish Attacked a Plesiosaur in Prehistoric Alabama
In the Western Interior Sea – a vast waterway that once divided North America in two during the Cretaceous Period – the fight for survival was not just between hunter and prey, but a true clash of the titans.
A new study, published in the Journal of Vertebrate Paleontologyhas revealed an embedded tooth in one of ancient Alabama’s fiercest marine predators. Using high-tech scanning, scientists discovered this hidden surprise hidden in a fossil that had been sitting in a museum drawer for decades. This new discovery rewrites our understanding of the ancient food chain and proves that even the ocean’s toughest inhabitants had very bad days.
“We sometimes have fixed ideas in our minds about who was the top predator in a given environment and who might be one or two rungs down the food chain. This fossil reminds us that nature is rarely this cut and dry,” lead author Stephanie Drumheller said in a press release.
Learn more: A 66 million year old man Tyrannosaurus Tooth embedded in a Edmontosauruss Skull reveals violent final encounter
CT scans reveal tooth in plesiosaur fossil
The story begins at the Field Museum of Natural History in Chicago, where a four-meter-long statue Polycotyl – a kind of plesiosaur – was hiding something. Although researchers discovered the fossil in Alabama’s Mooreville Chalk years ago, they didn’t notice the surprise until they took a closer look at its cervical vertebrae: a massive, crushed tooth embedded directly in the bone.
To identify the attacker without destroying the precious specimen, the team turned to computed tomography (CT) scanning. Two University of Tennessee undergraduate students virtually dissected the fossil and built a 3D model of the tooth.
This 3D model revealed a surprising culprit: the tooth belonged to Xiphactinusa huge predatory bony fish.
How did the tooth get stuck?
While Xiphactinus was the larger of the two species, it probably wasn’t trying to eat the plesiosaur. Numerous “fish within fish” fossils show that these predators generally preferred to swallow their meals whole.
Instead, the bite could be the result of a fight, perhaps over territory. Whatever the motive, the location of the bite was catastrophic.
“Plesiosaurs are famous for their long necks, but that neck comes at a price,” explained co-author Robin O’Keefe. “The trachea, the esophagus, the main arteries and veins, the important nerves: all these organs are vulnerable to attack. A bite to the neck by Xiphactinus would certainly have been fatal to this animal, if the Polycotyl wasn’t already dead.
Whether it’s a botched hunt or a scavenged meal, the violence required to insert a tooth into a vertebra suggests a terrifying level of power.
The Significance of Mooreville Chalk in Alabama
The Mooreville Chalk has long been a gold mine for paleontologists, providing a snapshot of a dynamic ecosystem where everything was on the menu. From sharks and bony fish to the occasional dinosaur that unfortunately found itself washed out to sea, the fossils unearthed here create a picture of a chaotic aquatic world where no species was safe.
This specific discovery highlights that the Western Inland Sea was a high-stakes area where even the largest predators were constantly looking over their shoulders.
Learn more: Discovery of a new species of carnivorous dinosaur with a crocodile in its teeth
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