The Therizinosaurus was a heftily-built, gigantic dinosaur that walked the planet in the late Cretaceous Period (about 70 million years ago). Very little is known about this ancient creature since only a very few fossilized specimens of its limbs and ribs could be excavated to date.

History and Discovery

In 1948, a Soviet-Mongolian fossil expedition was conducted, during which the first fossil of the Therizinosaurus was unearthed. The mission of this expedition was to study the Nemegt Formation (or Nemegtskaya Svita), a Late Cretaceous geological formation in Mongolia’s Gobi Desert. The excavations were a success, unearthing a few huge claws and some other parts that were thought to be horn sheaths. Each of these remaining was almost a meter long.

Later, in 1954, Russian paleontologist Evgeny Maleev presumed that these skeletal remains belonged to a large 4.5 m long, turtle-like reptile dwelling in the depths of the prehistoric waters, using its claws to crop seaweed. Maleev, finally, described and named it accordingly, assigning the new creature to the family Therizinosauridae.

However, in 1970, Anatoly Konstantinovich Rozhdestvensky, another veteran paleontologist from Russia, discarded the presumption of Maleev and rightly grouped it as a theropod dinosaur. Eventually, the very Therizinosauridae family was identified with the Segnosauridae (that included the Therizinosaurs), and the Therizinosaurus was included under the latter.

Further excavations were conducted in 1976, unearthing similar fossils, including claws and forelimbs, which were described by a Mongolian geologist and paleontologist Rinchen Barsbold. In 1982, again, yet another Mongolian paleontologist named Altangerel Perle described several other prehistoric fossil findings that consisted of large hind limbs. Finally, certain similar excavations belonging to a related species in the northern region of China helped the scientists to conclude about the animal’s general skeletal structure unanimously.

Physical Description

This giant-like dinosaur is known only from their excavated forelimb skeletons, and hence, their reconstructions of the creature are mostly guesswork. It is thought that they had a small head with the mouth ending in a beak, set on top of a long, slender neck.

While most of the other theropods used only three toes, the feet of the Therizinosaurus rested on four toes while walking and standing. The arms and the legs were 2.5 meters (8 feet) each. They had huge claws on the forelimbs measuring up to 70 cm in length, with the longest one being on the first digit. The incredibly large toe digits of these giant lizards are thought to be an adaptation to help them pull down the high branches of trees for consumption, as also, as a defense against predators.

Behavior

Based on limited data and scientific research, it is thought that they had a strong addiction to plants. Their enormous claws are probably evident of the fact that they lived in regions infested by a large number of predators like the contemporary Tarbosaurus. They are also thought to be territorial, getting frequently belligerent in intraspecific fighting. However, mating competitions can also be another reason for such fights.

Diet

Scientists are not yet sure whether the Therizinosaurus was herbivore, carnivore, or omnivore. However, it is more likely that they were plant-eaters since their close relatives are all known to be herbivorous. Yet, some paleontologists have claimed that their large claws were used to rip open giant termite nests, which would mean that the Therizinosaurus were insectivore.

Interesting Facts/Records

• The meaning of the term ‘Therizinosaurus’ means ‘the scythe lizard’, referring to the enormous, curved claws of the creature resembling a scythe.
• The finger bones of the reptile are larger than any other animal in history.
• Paleontologists are yet to uncover a Therizinosaurus skull, making it tough for them to have definitive evidence as to what their food habit was.
• Given that the Beipiaosaurus, its close relative, was feathered, there is a high chance that the Therizinosaurus also had feathers all over its body, serving two functions – to keep it warm, as also, to attract the opposite sex.
• There is a life-size statue of the Therizinosaurus at the Jurapark in the Polish village of Baltow.
• In the recent past, in 2013, a nest of the Therizinosaur with 17 clutches of eggs was found in the Gobi Desert.