Dinosaurs, a group of reptiles that dominated Earth for over 160 million years, evolved unique features to thrive in diverse environments. Among their many remarkable traits, the development of unusual claws stands out as a testament to their evolutionary ingenuity.
Identifying the Long-Clawed Dinosaur
The dinosaur most renowned for its exceptionally long claws is Therizinosaurus. This creature, whose name means “scythe lizard,” lived approximately 70 million years ago during the Late Cretaceous period in what is now Mongolia. Unlike most theropods, which were carnivorous, Therizinosaurus evolved to be herbivorous, a surprising dietary shift for its lineage.
Its most striking feature was the colossal claws on each of its three-fingered hands. These claws are considered the longest of any known land animal, reaching lengths of up to 50 centimeters (20 inches) along their outer curve. The animal was large, estimated to be between 9 to 10 meters (30 to 33 feet) long and 4 to 5 meters (13 to 16 feet) tall, weighing over 5 tons. Early fossil discoveries were limited, leading to initial confusion about its classification, with some paleontologists even mistaking its remains for those of a giant turtle.
The Purpose and Peculiarities of Therizinosaurus Claws
The exact function of Therizinosaurus’s remarkably long claws has been a subject of scientific discussion. One theory suggests they were used for foraging, allowing the dinosaur to pull down leafy branches from tall trees to access vegetation, similar to how modern sloths or anteaters use their claws. The robust nature of its forelimbs supports the idea of these claws being used for a hook-and-pull action to strip vegetation.
Another hypothesis proposes the claws served as a defensive mechanism against large predators, such as the contemporary Tarbosaurus. Tarbosaurus was a large bipedal carnivore, reaching lengths of 10 to 12 meters (33 to 40 feet) and weighing up to 5 tons, making it a formidable threat in the Nemegt Formation. While the claws might have been used for intimidation, their fragility suggests they were not designed for tearing flesh like a predatory theropod. Some paleontologists also suggest they could have played a role in intraspecific fighting, such as for territory or mating displays.
Other Notable Dinosaur Claws
While Therizinosaurus holds the record for the longest hand claws, other dinosaurs also possessed distinctive claws adapted for various purposes. Dromaeosaurids, a group that includes Deinonychus and Velociraptor, are known for their large, sickle-shaped claws on the second toe of each hind foot. These “terrible claws” were likely used during predation to grasp and pin struggling prey, or to inflict small, repeated stabs.
Baryonyx, a fish-eating theropod, had a particularly large thumb claw. This substantial claw, measuring around 31 centimeters (12 inches) along its outer curve, was likely a tool for hooking slippery fish out of the water. The discovery of fish scales in its stomach supports its piscivorous diet. These diverse claw adaptations highlight how dinosaurs interacted with their environments and secured their survival.