Therizinosaurus ('scythe lizard', from the Greek therizo meaning 'to reap' or 'to cut off' and sauros meaning 'lizard') was a very large therizinosaur (previously known as segnosaur). It could grow up to 10-12 meters (33-40 feet) long and reach 3-6 tons in weight.^[1] Therizinosaurus lived in the late Cretaceous Period around 70-75 million years ago, and was one of the later and largest representatives of its unique group. Its fossils were first discovered in Mongolia and when it was discovered it was originally thought to be a turtle (hence the name cheloniformis - turtle-formed) but it is now accepted as a maniraptoran theropod dinosaur. Genera See text. ... A tonne (also called metric ton) is a non-SI unit of mass, accepted for use with SI, defined as: 1 tonne = 103 kg (= 106 g). ... The Cretaceous Period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic Period (i. ... A geologic period is a subdivision of geologic time that divides an era into smaller timeframes. ... Mega-annum, usually abbreviated as Ma, is a unit of time equal to one million years. ... FOSSIL is a standard for allowing serial communication for telecommunications programs under DOS. FOSSIL is an acronym for Fido Opus Seadog Standard Interface Layer. ... Diversity ca. ... Subgroups Alvarezsauria Aves Deinonychosauria Oviraptorosauria Therizinosauria Maniraptora is a group used in biological classification to cover the birds and the dinosaurs that were related to them. ... Families See text Theropods (beast foot) are a group of bipedal, primarily carnivorous dinosaurs, belonging to the saurischian (lizard-hip) family. ... Orders & Suborders Saurischia Sauropodomorpha Theropoda Ornithischia Thyreophora Ornithopoda Marginocephalia Dinosaurs were vertebrate animals that dominated the terrestrial ecosystem for over 160 million years, first appearing approximately 230 million years ago. ...

Discovery and Species

The first fossils now attributed to Therizinosaurus were discovered in the late 1940s by a joint Soviet-Mongolian fossil expedition. The expedition unearthed several giant claws that measured up to a meter in length. However, it was not known what creature these belonged to until the early 1950s, when further fossil expeditions unearthed more bones: several more sets of claws and parts of a forelimb and hindlimb. Subsequent finds in northern China allowed paleontologists to assemble the general skeletal structure of the animal, which was determined to be a dinosaur and not a turtle. In 1954, the animal was named Therizinosaurus ('scythe lizard'), referring to the enormous claws. At present, there is one accepted species - T. cheloniformis. Soviet redirects here. ... FOSSIL is a standard for allowing serial communication for telecommunications programs under DOS. FOSSIL is an acronym for Fido Opus Seadog Standard Interface Layer. ... Cat claw A claw is a curved pointed appendage, found at the end of a toe or finger or, in arthropods, of the tarsus. ... FOSSIL is a standard for allowing serial communication for telecommunications programs under DOS. FOSSIL is an acronym for Fido Opus Seadog Standard Interface Layer. ... Grays Anatomy illustration of a human femur. ... Diversity ca. ...

The recent discovery of several related dinosaurs - Alxasaurus in 1993 and Beipiaosaurus in 1996 - helped clarify the position of the therizinosaurs as a whole. Various theories had been proposed to explain the ancestry of these dinosaurs, with some scientists even suggesting they were descendents of the sauropodomorphs - but these new, well-preserved finds, giving details about the bird-like pelvis, feet and skulls, helped confirm that the therizinosaurs were all maniraptoran, theropod dinosaurs. Alxasaurus elesitaiensis Pronounced:Alx-ah-sor-uhss Diet:Herbivore(plants) Name Means:Alxa Desert Lizard Length:13 ft. ... Binomial name Beipiaosaurus inexpectus Xu, Tang & Wang, 1999 Beipiaosaurus inexpectus is a therizinosauroid, a member of a bizarre group of theropod dinosaurs. ... Groups Saturnalia Prosauropoda Sauropoda The Sauropodomorpha were a group of long-necked, herbivorous dinosaurs that eventually dropped down on all fours and became the largest animals that ever the walked the earth. ... The pelvis (pl. ... Subgroups Alvarezsauria Aves Deinonychosauria Oviraptorosauria Therizinosauria Maniraptora is a group used in biological classification to cover the birds and the dinosaurs that were related to them. ... Families See text Theropods (beast foot) are a group of bipedal, primarily carnivorous dinosaurs, belonging to the saurischian (lizard-hip) family. ...

Characteristics

Therizinosaurus had a small head with a beaked mouth, atop a long neck. It was bipedal and had a large, heavy, deep body, as evidenced by the wide pelvis, 2.5 meter (8 foot) long arms and legs that ended in four toes (three of which supported the animal's weight), which were tipped by short, curved claws. The most distinctive feature of the animal was the presence of three gigantic claws on its front limbs. Each of the three digits of its hand bore these claws, which reached nearly a meter (approximately 2-3 feet) in length. The largest claw was on the second digit.^[1] This article or section does not cite its references or sources. ... The pelvis (pl. ... Cat claw A claw is a curved pointed appendage, found at the end of a toe or finger or, in arthropods, of the tarsus. ...

The feeding habits of Therizinosaurus are still debated, but it was most probably an herbivore, using its big claws to push leaves into its mouth. Other hypotheses suggest that it was a termite eater, using its claws to open large termite nests - but it seems highly unlikely that an animal the size of Therizinosaurus could survive on a diet based on insects and features of the skull (including a beaked mouth and flattened teeth) suggest a herbivorous diet.^[1] It is thought that Therizinosaurus lived a similar lifestyle to modern gorillas or prehistoric ground sloths, using its long arms and sharp claws to grab food and foliage from trees. A deer and two fawns feeding on some foliage A herbivore is often defined as any organism that eats only plants[1]. By that definition, many fungi, some bacteria, many animals, about 1% of flowering plants and some protists can be considered herbivores. ... Families Mastotermitidae Kalotermitidae Termopsidae Hodotermitidae Rhinotermitidae Serritermitidae Termitidae Termites, sometimes known as white ants, are a group of social insects usually classified at the taxonomic rank of order Isoptera. ... Type species Troglodytes gorilla Savage, 1847 distribution of Gorilla Species Gorilla gorilla Gorilla beringei The gorilla, the largest of the living primates, is a ground-dwelling omnivore that inhabits the forests of Africa. ... Families Rathymotheriidae Scelidotheriidae Mylodontidae Orophodontidae Megalonychidae Megatheriidae Ground sloths are extinct edentate (Order Xenarthra) mammals that are believed to be relatives of tree sloths and three-toed sloths. ...

There are other possible functions that could have been served by the claws of Therizinosaurus, such as defense against predators (e.g. the contemporary Tarbosaurus) and in intraspecific fighting, such as fighting for territory or for mating. The claws may even have served all these functions. Binomial name Tarbosaurus bataar Maleev, 1955 Tarbosaurus, meaning Terror Lizard (from the Greek tarbos/ταρβος meaning fright, alarm, terror (interestingly it can also mean awe or reverence[1]) and saurus/σαυρος meaning lizard), was a member of the dinosaur family of tyrannosaurids, which flourished during the early Maastrichtian of the Late Cretaceous...

It is highly likely that Therizinosaurus was feathered, given that its close relative Beipiaosaurus certainly was. Binomial name Beipiaosaurus inexpectus Xu, Tang & Wang, 1999 Beipiaosaurus inexpectus is a therizinosauroid, a member of a bizarre group of theropod dinosaurs. ...

References

• Parker, S. (2003). Dinosaurus, 1st ed. Buffalo, NY: Quintet Publishing Ltd.

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