Baryonyx was a distinctive theropod dinosaur that roamed the riverine landscapes of what is now England during the Early Cretaceous period, approximately 130 to 125 million years ago. As a member of the Spinosauridae family, it shared characteristics with its larger African relative, Spinosaurus, but possessed its own unique features. Its discovery revealed a specialized predatory niche previously unknown among large theropods, reshaping scientific understanding of dinosaur diversity.
The Discovery of Heavy Claw
The story of Baryonyx begins in a clay pit in Surrey, England. In January 1983, an amateur fossil hunter named William J. Walker was exploring the Smokejacks Pit near Ockley when he unearthed a massive, fossilized claw. After finding more bone fragments, Walker brought his discovery to paleontologists at London’s Natural History Museum.
This prompted a full-scale excavation of the site, led by paleontologists Alan J. Charig and Angela C. Milner. Their efforts led to the recovery of about 70 percent of a single skeleton, making it one of the most complete theropod skeletons ever found in the United Kingdom. In 1986, the new dinosaur was named Baryonyx walkeri, which translates to “Walker’s heavy claw,” honoring its discoverer and the claw that signaled its existence.
Distinctive Physical Features
The most striking feature of Baryonyx was the huge claw on the first finger of each hand. The bone core of this claw measured 31 centimeters (about 12 inches) along its outer curve; in life, a keratin sheath would have made it even larger and sharper. This “heavy claw” was a powerful tool, unlike the smaller, three-fingered hands of many other carnivorous dinosaurs.
Its skull was also highly specialized, bearing a long, narrow snout that resembled that of a modern gharial. This elongated jaw was filled with a large number of conical, finely serrated teeth, a stark contrast to the blade-like teeth of dinosaurs like Tyrannosaurus rex. Baryonyx had nearly double the number of teeth found in some other large theropods.
The discovered specimen, believed to be not yet fully grown, was estimated to be between 7.5 and 9 meters (25 to 30 feet) long and weigh between 1.2 and 2 metric tons. This made Baryonyx a large predator, but more lightly built than some giant theropods.
A Fish-Eating Predator’s Diet
The fossil of Baryonyx walkeri offered insight into its diet, providing the first direct evidence of fish-eating (piscivory) in a non-avian dinosaur. Within the stomach region of the skeleton, scientists found acid-etched scales and teeth from a fish called Lepidotes.
The powerful thumb claws were likely used to gaff or hook fish, similar to the way grizzly bears catch salmon today. Once caught, the conical teeth would have provided a firm grip, preventing the struggling fish from escaping. This feeding strategy is very different from the bone-crushing bites employed by other large theropods.
However, Baryonyx was not limited to a diet of fish. The same stomach contents also contained the acid-etched bones of a young Iguanodon, a common herbivorous dinosaur. This suggests Baryonyx was an opportunistic predator and scavenger, supplementing its primary fish diet with land animals.
The World of Baryonyx
During the Barremian stage of the Early Cretaceous, the region of modern-day England was a warm, subtropical landscape dominated by vast floodplains, meandering rivers, and large lakes. These environments are preserved in the series of rock layers known as the Wealden Group, which has yielded a rich diversity of fossils. This wetland setting provided the hunting ground for a semi-aquatic predator like Baryonyx.
The world of Baryonyx was populated by a diverse array of other dinosaurs. It shared its habitat with large herbivores like Iguanodon and the armored dinosaur Polacanthus, creating a complex ecosystem.