Therizinosaurus ‭(‬Scythe lizard‭)‬

Short Info

Therizinosaurus ‭(‬Scythe lizard‭)‬

Phonetic : Ther-ih-zine-oh-sore-us

Named By : Evgeny Maleev‭ ‬-‭ ‬1954

Diet : Probably Herbivore

Size : Estimated 10 meters long

Type of Dinosaur : Large Theropod

Type Species : T.‭ ‬cheloniformis‭ (‬type‭)‬

Found in : Mongolia

When it Lived : Late Cretaceous, 85-70 million years ago

Therizinosaurus (/,ther@,zInoU’so:r@s/; meaning ‘scythe lizard’) is a genus of very large therizinosaurid that lived in Asia during the Late Cretaceous period in what is now the Nemegt Formation around 70 million years ago. It is the only species that is known as Therizinosaurus cheloniformis. The initial remains of the Therizinosaurus were discovered in the year 1948 during an Mongolian field trip in the Gobi Desert. They were later was described by Evgeny Maleev in 1954. The genus is recognized only through a handful of bones, which include massive manual unguals (claw bones) that are the reason it is named and further findings that include hindlimb and forelimb parts which were found during the 1960s to 1980s.


Therizinosaurus armsYuya Tamai from Gifu, Japan, CC BY 2.0, via Wikimedia Commons


Therizinosaurus was a huge therizinosaur that was able to grow to 9-10 meters (30-33 feet) in length and weigh more than 3 tonnes (3,000 kilograms). Similar to other therizinosaurs was slow-moving, long-necked browser with the Rhamphotheca (horny beak) and a broad torso to process food. The forelimbs were extremely robust , with three fingers with unguals, which, unlike cousins, were stiff, elongated, and had significant curvatures on the edges. Therizinosaurus had the longest-known manual unguals in any animal exceeding 50 centimeters (500 millimeters) long. The hindlimbs of the animal ended in four toes with a weight bearing function that differed from other groups of theropods with the primary one was reduced into a dewclaw, being a close kin to the sauropodomorphs that were not related.

It was the most important and longest-running representations of the unique group, called the Therizinosauria (formerly called Segnosauria and the segnosaurs). In the years following its initial publication during 1954 Therizinosaurus featured a variety of relations due to the lack of complete specimens and related species in the time. Maleev believed that The remains from Therizinosaurus to be part of an enormous turtle-like reptile and also named a distinct family within the genus of Therizinosauridae. In the later years, after discovering more extensive relatives Therizinosaurus and its kin were believed to be a type or Late Cretaceous sauropodomorphs or transitional ornithischians. Nevertheless, at one point, it was believed that it might be a theropod. Following many years of debate on taxonomy, however, they have been classified as part of one of the most important dinosaur clans, Theropoda, specifically as maniraptorans. Therizinosaurus is extensively identified within Therizinosauridae in the majority of studies.

The peculiar arms and body structure (extrapolated following relatives) of the Therizinosaurus are mentioned as an example of convergent evolution in chalicotheriines as well as other herbivores, primarily mammals, which suggests similar food habits. The hand claws that were elongated of the Therizinosaurus were more effective for pulling vegetation that was within reach rather than to defend or attack because of their fragility but they could serve as a means of the purpose of intimidation. They were also resistant to pressure, which indicates an extensive use of the arms. Therizinosaurus was a large animal, and likely to have an advantage over vegetation in its natural habitat and out-matching predators like Tarbosaurus.

In 1948, a number of Mongolian Paleontological expeditions organized by the USSR Academy of Sciences were carried out at the Nemegt Formation of the Gobi Desert in Southwestern Mongolia, with the primary goal of finding discoveries of new fossils. The expeditions discovered a variety of fossil remains of dinosaurs and turtles from the locality of stratotype Nemegt (also called Nemegt Valley), but the most significant elements discovered were three manual unguals (claw bones) with a size of over a meter. These unguals were discovered on a subdivision of the Nemegt location that is identified as Quarry V, which is located near the skeleton of an enormous theropod. It was also found as a part of other elements such as a metacarpal bone fragment and fragments of ribs. The specimen was identified with the specimen number PIN 551-483. Later the fossils were described by Russian paleontologist Evgeny Maleev in the year 1954. He employed them to scientifically identify the new genus and the type species Therizinosaurus cheloniformis. This was later adopted as the Holotype specimen. The general name, Therizinosaurus is taken from The Greek therizo (therizo that means scythe or reaping or cutting) as well as sauros (sauros meaning it means lizard) with reference to huge manual unguals. The particular name, cheloniformis originates form The Greek khelone (cheloni which means the turtle) in addition to Latin formis, since the remains were believed to be an animal that resembled a turtle. Maleev also coined a new family for this brand new and mysterious taxon called Therizinosauridae. Since there was not much information on Therizinosaurus when it was first described its initial classification, Maleev thought PIN 551-483 was the name of a massive, 4.5 m (15 ft) long reptile that used its massive hand claws to collect seaweed.

While it wasn’t fully realized to what type species of creature these fossils belong to however, in the year 1970, it was discovered that the Russian paleontologist Anatoly K. Rozhdestvensky was one of the first researchers to propose the possibility that Therizinosaurus could be a theropod, and not the turtle. He used comparisons of Chilantaisaurus as well as the Holotype unguals from Therizinosaurus to suggest that the appendages are actually from carnosaurian dinosaurs thus interpreting Therizinosaurus as an theropod. Rozhdestvensky further illustrated the three Holotypic manuals unguals, and identified the metacarpal bone fragment as a bone of the metatarsal, as well as based on the peculiar form of both the metatarsal as well as the ribs fragments, he classified as remains of a sauropod. These theropodan affinities were also followed by the Polish paleontologist Halszka Osmolska and co-author Ewa Roniewicz in 1970 during their naming and description of Deinocheirus–another large and enigmatic theropod from the formation that was initially known from partial arms. Like Rozhdestvensky the authors suggested that the holotype unguals are more likely to belong to the carnosaurian theropod rather than an enormous marine turtle.

Source: Wikipedia