Therizinosaurus

Therizinosaurus is one of the strangest dinosaurs ever discovered, a towering creature that looked like something assembled from spare parts. Despite its fearsome appearance and massive claws, this Late Cretaceous giant was almost certainly a herbivore, using those extraordinary appendages to pull down tree branches rather than to attack prey. It belonged to the therizinosaur family, a peculiar group of theropods that abandoned the carnivorous lifestyle of their ancestors.

The first fossils were discovered in 1948 by a Soviet-Mongolian expedition in the Gobi Desert of Mongolia. When paleontologist Evgeny Maleev described them in 1954, he initially thought the enormous claws belonged to a giant turtle-like reptile — hence the species name 'cheloniformis,' meaning 'turtle-formed.' It wasn't until additional limb bones were found in the 1960s through 1980s that scientists realized they were dealing with a dinosaur.

Therizinosaurus remains frustratingly incomplete. No skull has ever been found, and most of what we know about its full body plan comes from better-preserved relatives like Nothronychus and Erlikosaurus. Based on these relatives, Therizinosaurus likely had a small head, long neck, pot-bellied body for digesting plant material, and stood upright on powerful hind legs.

The sheer size of this animal is remarkable — estimates suggest it could reach 9 to 10 meters in length, making it one of the largest theropods and certainly the largest of its bizarre family. Those iconic claws, measuring up to 70-100 centimeters along the outer curve, may have served multiple purposes: defense against predators like Tarbosaurus, competing for mates, or stripping vegetation from trees much like a giant ground sloth.