Cuba the Therizinosaurus

## Cuba

Cuba the Therizinosaurus

This is the the Strongest Female Therizinosaurus Cuba From Western China Therizinosaurus Had an Angry Look Cuba Has Meter Long Fingernails bent nail Smell Hook Cuba is very Curious

## Information

***Therizinosaurus*** (/ˌθɛrəˌzɪnoʊˈsɔːrəs/; 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 contains a single species, ***Therizinosaurus cheloniformis***. The first remains of *Therizinosaurus* were found in 1948 by a Mongolian field expedition at the Gobi Desert and later described by Evgeny Maleev in 1954. The genus is only known from a few bones, including gigantic manual unguals (claw bones), from which it gets its name, and additional findings comprising fore and hindlimb elements that were discovered from the 1960s through the 1980s.

*Therizinosaurus* was a colossal therizinosaurid that could grow up to 9–10 m (30–33 ft) long and 4–5 m (13–16 ft) tall, and weigh possibly over 5 t (5.5 short tons). Like other therizinosaurids, it would have been a slow-moving, long-necked, high browser equipped with a rhamphotheca (horny beak) and a wide torso for food processing. Its forelimbs were particularly robust and had three fingers that bore unguals which, unlike other relatives, were very stiffened, elongated, and only had significant curvatures at the tips. *Therizinosaurus* had the longest known manual unguals of any land animal, reaching above 50 cm (20 in) in length. Its hindlimbs ended in four functionally weight-bearing toes differing from other theropod groups in which the first toe was reduced to a dewclaw and also resembling the very distantly related sauropodomorphs.

It was one of the last and the largest representative of its unique group, the Therizinosauria (formerly known as Segnosauria; the segnosaurs). During and after its original description in 1954, *Therizinosaurus* had rather complex relationships due to the lack of complete specimens and relatives at the time. Maleev thought the remains of *Therizinosaurus* to belong to a large turtle-like reptile, and also named a separate family for the genus: Therizinosauridae. Later on, with the discovery of more complete relatives, *Therizinosaurus* and kin were thought to represent some kind of Late Cretaceous sauropodomorphs or transitional ornithischians, even though at some point it was suggested that it may have been a theropod. After years of taxonomic debate, nevertheless, they are now placed in one of the major dinosaur clades, Theropoda, specifically as maniraptorans. *Therizinosaurus* is widely recovered within Therizinosauridae by most analyses.

The unusual arms and body anatomy (extrapolated after relatives) of *Therizinosaurus* have been cited as an example of convergent evolution with chalicotheriines and other primarily herbivorous mammals, suggesting similar feeding habits. The elongated hand claws of *Therizinosaurus* were more useful when pulling vegetation within reach rather than being used for active attack or defense because of their fragility, however, they may have had some role for intimidation. Its arms also were particularly resistant to stress, which suggests a robust use of these limbs. *Therizinosaurus* was a very tall animal, likely having a reduced competition over the foliage in its habitat and outmatching predators like *Tarbosaurus*.

## History of discovery[edit]

link=https://en.wikipedia.org/wiki/File:Cretaceous-aged\_dinosaur\_fossil\_localities\_of\_Mongolia.PNG|left|thumb|Cretaceous fossil localities of Mongolia; *Therizinosaurus* fossils have been collected from the Altan Uul, Hermiin Tsav, and Nemegt localities at the area A (Nemegt Formation)
In 1948, several Mongolian Paleontological expeditions organized by the USSR Academy of Sciences were conducted in the Nemegt Formation of the Gobi Desert, Southwestern Mongolia, with the main objective of new fossils findings. The expeditions unearthed numerous dinosaur and turtle fossil remains from the stratotype locality Nemegt (also known as Nemegt Valley), but the most notable elements collected were three partial manual unguals (claw bones) of considerable size. This set of unguals was found on a subdivision of the Nemegt locality designated as Quarry V near the skeleton of a large theropod, but also in association with other elements including a metacarpal fragment and several ribs fragments. It was labelled under the specimen number **PIN 551-483** and later on, these fossils were described by the Russian paleontologist Evgeny Maleev in 1954 who used them to scientifically name the new genus and type species *Therizinosaurus cheloniformis*, becoming the holotype specimen. The generic name, *Therizinosaurus*, is derived from the Greek θερίζω (*therízo*, meaning scythe, reap or cut) and σαῦρος (*sauros*, meaning lizard) in reference to the enormous manual unguals, and the specific name, *cheloniformis*, is taken from the Greek χελώνη (*chelóni*, meaning turtle) and Latin formis as the remains were thought to belong to a turtle-like reptile. Maleev also coined a separate family for this new and enigmatic taxon: Therizinosauridae. Since little was known of *Therizinosaurus* at the time of the original description, Maleev thought PIN 551-483 belonged to a large, 4.5 m (15 ft) long turtle-like reptile that relied on its giant hand claws to harvest seaweed.
link=https://en.wikipedia.org/wiki/File:Therizinosaurus\_PIN\_551-483\_unguals.jpg|thumb|Holotype unguals PIN 551–483 at the Moscow Paleontological Museum; note left ungual cast
Though it was not fully understood to what general kind of animal these fossils belonged, in 1970, the Russian paleontologist Anatoly K. Rozhdestvensky was one of the first authors to suggest that *Therizinosaurus* was a theropod and not a turtle. He made comparisons between *Chilantaisaurus* and the holotype unguals of *Therizinosaurus* to propose that the appendages actually came from a carnosaurian dinosaur, thereby interpreting *Therizinosaurus* as a theropod. Rozhdestvensky also illustrated the three holotypic manual unguals and re-identified the metacarpal fragment as a metatarsal bone, and based on the unusual shape of both metatarsal and ribs fragments he listed them as sauropod remains. These theropodan affinities were also followed by the Polish paleontologist Halszka Osmólska 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. Similar to Rozhdestvensky, they suggested that the holotype unguals were more likely to have belonged to a carnosaurian theropod, rather than a large marine turtle.

### Additional specimens[edit]

link=https://en.wikipedia.org/wiki/File:Therizinosaurus\_MPC-D\_100\_15\_arms.jpg|left|thumb|Arms of specimen MPC-D 100/15 with unguals 100/16 and 100/17 at CosmoCaixa Barcelona
Further expeditions in the Nemegt Formation unearthed more fossils of *Therizinosaurus*. In 1968 prior to Rozhdestvensky, Osmólska and Roniewicz statements, the upper portion of a manual ungual was found in the Altan Uul locality and labeled as MPC-D 100/17 (formerly IGM or GIN). In 1972, another fragmented ungual (specimen MPC-D 100/16) was discovered at the Upper White Beds of the Hermiin Tsav locality, only preserving its lower portion. During the year 1973, a much more complete, larger, and articulated specimen was collected also from Hermiin Tsav. This specimen was labelled as MPC-D 100/15 and consists of both left and right arms including the scapulocoracoids, both humeri (upper arm bones), right ulna with radius and left ulna, two right carpals, the right metacarpus including a complete digit Il, and some ribs with gastralia (belly ribs). As common with fossils, some elements were not entirely preserved such as the scapulocoracoids with broken ends, and the left arm is less complete than the right one. All of these specimens were first described and referred to *Therizinosaurus* by the Mongolian paleontologist Rinchen Barsbold in 1976. In this new monograph, he pointed out that the rib fragments in MPC-D 100/15 were more slender than the ones from the holotype, and identified MPC-D 100/16 and 100/17 as pertaining to digits I and III, respectively. It was clear to Barsbold that MPC-D 100/15 represented *Therizinosaurus* as the ungual in this specimen shared the elongation and flattened morphology of all previous specimens. He concluded that *Therizinosaurus* was a theropod taxon since MPC-D 100/15 matched multiple theropodan characters.
link=https://en.wikipedia.org/wiki/File:Therizinosaurus\_known\_material.jpg|thumb|Composite skeletal of the known remains of *Therizinosaurus*
Also during the year 1973, the specimen MPC-D 100/45 was discovered by the Joint Soviet-Mongolian Paleontological Expedition at the Hermiin Tsav locality. Unlike the previous findings, MPC-D 100/45 is represented by a right hindlimb composed of a very fragmented femur with the lower end of the tibia, astragalus, calcaneum, tarsal IV, a functional tetradacyl feet (four-toed) compromising four partial metatarsals, partially preserved digits I and III, and nearly complete digits II and IV. These newer remains were described by the also Mongolian paleontologist Altangerel Perle in 1982. He regarded the referral of *Therizinosaurus* and Therizinosauridae to Chelonia (turtles order) to be unlikely, and hypothesized *Therizinosaurus* and *Segnosaurus*—at the time of this description regarded as a theropod dinosaur—to be particularly similar based on their respective scapulocoracoid morphology, only differing in size. Perle referred MPC-D 100/45 to *Therizinosaurus* given that this specimen was found near the location of MPC-D 100/15 and was virtually similar to the described pes for *Segnosaurus*. In 1990, Barsbold and Teresa Maryanska agreed with Perle in that the hindlimb material from Hermiin Tsav he described in 1982 was therizinosaurian (then called segnosaurians) given that the metatarsus was stocky and the astragalus had a laterally arched ascending process (bony extension), but cast doubt with his referral of it to *Therizinosaurus* and the segnosaurian identity for this taxon since it was only known from the pectoral girdle and other forelimb elements, making direct comparisons between specimens impossible. They considered this specimen to represent a Late Cretaceous representative of the Segnosauria, but not *Therizinosaurus*.

In 2010 however, the North American paleontologist Lindsay E. Zanno in her large taxonomic reevaluation of Therizinosauria considered the referral of MPC-D 100/45 to *Therizinosaurus* to be likely based on the rationale that it was collected in the same stratigraphic context (Nemegt Formation) as the holotype, and shared the robust and four-toed morphology of other therizinosaurids such as *Segnosaurus*. She also excluded the rib material from the holotype as it was re-identified by Rozhdestvensky to likely have come from a sauropod dinosaur, and not *Therizinosaurus* itself.

## Description[edit]

link=https://en.wikipedia.org/wiki/File:Therizinosaurus\_size.png|left|thumb|Size of two specimens (holotype in yellow, right) compared to a 1.8 m (5.9 ft) tall human
For maniraptoran standards, *Therizinosaurus* obtained enormous sizes, estimated to have reached 9 to 10 m (30 to 33 ft) in length with estimated heights from 4 to 5 m (13 to 16 ft) and ponderous weights from 3 t (3.3 short tons) to possibly over 5 t (5.5 short tons). These dimensions make *Therizinosaurus* the largest therizinosaur known and the largest known maniraptoran. Along with the contemporaneous ornithomimosaur *Deinocheirus*, it was the largest maniraptoriform. Though the body remains of *Therizinosaurus* are relatively incomplete, inferences can be made about its physical characteristics based on more complete and related therizinosaurids. Like other members of its family, *Therizinosaurus* had a proportionally small skull bearing a rhamphotheca (horny beak) atop its long neck; bipedal gaits; a large belly for foliage processing; and sparse feathering. Other traits that were likely present in *Therizinosaurus* include a heavily pneumatized (air-filled) vertebral column and a robustly-built, ophistopubic (backwards oriented) pelvis.
link=https://en.wikipedia.org/wiki/File:Therizinosaurus\_Restoration.png|thumb|Life restoration
In 2010, Senter and James used hindlimb length equations to predict the total length of the hindlimbs in *Therizinosaurus* and *Deinocheirus*. They concluded that an average *Therizinosaurus* may have had approximately 3 m (9.8 ft) long legs. More recently, Mike Taylor and Matt Wedel suggested that the whole neck would be 2.9 times the size of the humerus, which was 76 cm (760 mm), resulting in a 2.2 m (7.2 ft) long neck based on comparisons with the cervical vertebrae series of *Nanshiungosaurus*. The most distinctive feature of *Therizinosaurus* was the presence of gigantic unguals on each of the three digits of its hands. These were common among therizinosaurs but particularly large and stiffened in *Therizinosaurus*, and they are considered as the longest known from any terrestrial animal.

### Forelimbs[edit]

link=https://en.wikipedia.org/wiki/File:Therizinosaurus\_arm\_diagram.png|left|thumb|Diagram of the right arm and shoulder blade (rotated) of MPC-D 100/15
The arm of *Therizinosaurus* covered 2.4 m (7.9 ft) in total length (humerus, radius and second metacarpal with phalanges lengths). The scapula measured 67 cm (26 in) long with a stocky and flattened dorsal blade, wide acromial process (bony extension) and a very widened ventral surface. Near the anterior edge of the scapular widening and near the scapulocoracoid suture (bone joint), a foramen was located; it likely functioned as a channel for blood vessels and nerves when alive. The posterior edge of the scapula was robust and the acromion was lightly built, likely fused into a cartilaginous system with its periphery in life. The coracoid measured 36 cm (14 in) in length, it had a broad and convex lateral surface that formed a slightly inclined concavity near of the scapulocoracoid suture. This concavity bent down towards the scapular widening. Near the scapulocoracoid suture, this edge turned very thin and possibly into cartilage along with the periphery of the coracoid in life, as the case of the scapular edge. A large foramen was also present on the coracoid. The glenoid was broad and deep, slightly pointing to the outer lateral side. It had robust and convex crest-like borders. The supraglenoid thickness was developed in a convex crest-shaped form, it was divided across the top of the scapulocoracoid suture. The attachment for the biceps muscle was prominently developed by a large tubercle with a stocky top, indicating powerful muscles in life.

The humerus was robustly built, measuring 76 cm (30 in) long. It had a broad upper end. The deltopectoral crest (deltoid muscle attachment) was particularly long and thick, with its top located approximately 1/3 from the upper end. The length of the crest was no less than 2/3 the length of the whole bone element. The lower end of the humerus was very expanded and flared. The condyles were developed onto the anterior side of the lower expansion while the epicondyles were very broad and projected over the limits of the articular areas. The ulna measured 62.02 cm (24.42 in) and most of its length was occupied by its straight shaft. The ulnar process was very wide. The upper articular area was divided into inner and outer lateral sides. The lateral side had a triangular-shaped border and was slightly concave; it was limited in a top view by the depression for the upper articulation of the radius. The inner side formed a semilunar-shaped depression that covered the lunar-shaped condyle of the humerus. The radius was 55.04 cm (21.67 in) long and slightly S-curved. Its upper end was flattened in a lateral direction, very wide, and the distal end was highly robust.
link=https://en.wikipedia.org/wiki/File:Therizinosaurus\_ungual\_specimens.png|thumb|Skeletal diagram featuring the known unguals of *Therizinosaurus*
The first lower carpal bone measured 8.23 cm (3.24 in) tall and 8.53 cm (3.36 in) wide and had two articulation surfaces on its lowermost end. The upper surface of this carpal was divided by a broad depression that formed the articulation of the carpus. On its inner side, it had a triangular-shaped outline that attached to the upper surface of metacarpal I, occupying a little bit less than the lateral side, which articulates to metacarpal II. These areas were separated by an oblique bony projection. The second lower carpal was smaller than the first one, measuring 5.6 cm (2.2 in) tall and 5.93 cm (2.33 in) wide. Its lower surface was flattened and the articular surface of the carpus extended from the first carpal to the second carpal over the articulation of the two bones.

The metacarpal I was 14.55 cm (5.73 in) long and compared to the others it was more stockier. Its lateral side was broad, especially on the uppermost area; the inner border was thin and narrow. The upper articulation was configured into three parts. The lower articular surface was somewhat asymmetric and bent to the inner side from the left one, along with a wide and deep opening. The total length of this metacarpal was larger than 2/3 the length of metacarpal III, which may have been a unique trait of *Therizinosaurus*. The metacarpal II measured 28.68 cm (11.29 in) in length and was the most elongated and robust metacarpal. It had an inclined, square-shaped, and flattened upper articulation. The articulation on the lower head had very symmetrical condyles, being divided by a broad, deep depression. The lateral connecting openings were poorly developed. The metacarpal III covered 19.16 cm (7.54 in) in length and had a very thin shaft compared to the other metacarpals. Its upper articulation was divided into three parts. The lower articular head was asymmetrical with deep and broad openings. As in metacarpal II, the lateral connecting openings were poorly developed.
Only the second digit of the manus is known in *Therizinosaurus*. It consisted of two phalanges and a large ungual. The first and second phalanges were somewhat equal in shape and length (14.17 cm (5.58 in) and 14.38 cm (5.66 in), respectively), and shared the robust and stocky structure. The upper articular facets were very symmetrical and had a crest—particularly taller in the first phalanx. The top border of this crest was very pointed and thick; it likely served as the site for attachment of the extensor tendons in life. The lower heads were nearly symmetrical, but the central depression was considerably wider and deeper in the first phalanx. The manual unguals of *Therizinosaurus* were especially enormous and long, estimated to have covered approximately 52 cm (20 in) in length. Unlike other therizinosaurs they were very straight, side to side flattened, and had sharp curvatures only at the tips, a unique feature of *Therizinosaurus*. The lower tubercle, where the flexor tendons attached to the ungual, was thick and robust, indicating a large pad in life. The articulation surface that connected the preceding phalanx was slightly concave and divided into two by a central ridge.

### Hindlimbs[edit]

link=https://en.wikipedia.org/wiki/File:Therizinosaurus\_IGM\_100\_45\_diagram.png|thumb|Labelled diagram of the referred pes specimen MPC-D 100/45
*Therizinosaurus* had a rather stocky and robust tibia that was very wide on its lower end. The metatarsus was robust and short (almost sauropodomorph-like), and composed of five metatarsals. The first four were functional and terminated in weight-bearing digits, hence having a tetradactyl (four-toed) condition. The last or fifth metatarsal was highly reduced bone located at the lateral side of the metatarsus and had no functional significance. Unlike most other theropods groups, the first pedal digit was—though shorter than the others—functional and weight-bearing. The second and third were equally long while the fourth was smaller and somewhat thinner. The pedal unguals were side to side flattened and likely sharp. The morphology of the feet of *Therizinosaurus* and other therizinosaurids was unique, as the general theropod formula includes tridactyl (three-toed) feet in which the first toe was reduced to a dewclaw and held off the ground.

## Classification[edit]

See also: Timeline of therizinosaur research
link=https://en.wikipedia.org/wiki/File:Erlikosaurus.jpg|left|thumb|Outdated quadrupedal, sauropodomorph-like restoration of *Erlikosaurus*
Maleev originally classified *Therizinosaurus* as a giant marine turtle and the genus was assigned by him to a separate family, Therizinosauridae given how enigmatic the specimen was. The fossils remained with uncertainty among the scientific community; however, in 1970 Rozhdestvensky was one of the first paleontologists to suggest that *Therizinosaurus* was actually a theropod dinosaur instead of a turtle. He also suggested that the supposed ribs of the holotype were likely from a different dinosaur, possibly a sauropodomorph. In 1976 Barsbold concluded that *Therizinosaurus* was a theropod because MPC-D 100/15 matched numerous theropodan characters, and that Therizinosauridae and Deinocheiridae were probably synonyms. With the discovery and description of *Segnosaurus*, in 1979 Perle named a new family of dinosaurs, the *Segnosauridae*. He tentatively placed the family within Theropoda given the similarities of the mandible and dentition to other members. A year later, the new genus *Erlikosaurus* was named by Barsbold and Perle in 1980. They named a new infraorder called the Segnosauria, composed of *Erlikosaurus* and *Segnosaurus*. They also noted that while aberrant and having ornithischian-like pelves, segnosaurs featured similar traits to other theropods. With the discovery of the referred hindlimb to *Therizinosaurus* in 1982 by Perle, he concluded that *Segnosaurus* was very similar to the latter based on the morphology and they possibly belonged to a single, if not the same, group. In 1983, Barsbold named a new genus of segnosaur, *Enigmosaurus*. He analyzed the pelvis of the new genus and pointed out that segnosaurids were so different from other theropods that they could be outside the group or represent a different lineage of theropod dinosaurs. Later on the same year, he intensified the exclusion of segnosaurs from being theropods by noting that their pelves resembled those of sauropod dinosaurs.
link=https://en.wikipedia.org/wiki/File:Alxasaurus\_Tyrrell.jpg|thumb|Mounted skeleton of *Alxasaurus* at the Royal Tyrrell Museum. *Alxasaurus* helped to resolve important aspects about the affinities of the long-enigmatic therizinosaurs
Consequently, the assignment of segnosaurs started to shift towards sauropodomorphs. In 1984, Gregory S. Paul claimed that segnosaurs, rather than being theropods, were indeed sauropodomorphs that successfully managed to remain in the Cretaceous period. He based the idea on anatomical traits such as the skull and similar configuration. He maintained his position in 1988 by placing the Segnosauria into the now obsolete Phytodinosauria, and was one of the first to suggest a segnosaur assignment for the enigmatic *Therizinosaurus*. Other prominent paleontologists like Jacques Gauthier or Paul Sereno supported this vision. In 1990, Barsbold and Teresa Maryanska agreed in that the hindlimb material from Hermiin Tsav referred to *Therizinosaurus* in 1982 was segnosaurian since it matched several traits, but considered it unlikely to belong to the genus and species as there was no overlapping material among specimens. Barsbold and Maryanska also disagreed with previous researchers who classified *Deinocheirus* as a segnosaur. In the same year, David B. Norman considered *Therizinosaurus* to be a theropod of uncertain classification.
link=https://en.wikipedia.org/wiki/File:Beipiaosaurus-Paleozoological\_Museum\_of\_China.jpg|left|thumb|Feather impressions from the holotype of *Beipiaosaurus*
However, with the unexpected discovery and description of *Alxasaurus* in 1993, the widely accepted sauropodomorph affinities of segnosaurs were questioned by paleontologists Dale Russell and Dong Zhiming. This new genus was far more complete than any other segnosaur and multiple anatomical features indicated that it was related to *Therizinosaurus*. With this, they identified the Therizinosauridae along with the Segnosauridae to be the same group, the former name having taxonomic priority. Due to some primitive characters present in *Alxasaurus* they coined a new taxonomic rank, the Therizinosauroidea, containing the new taxon and Therizinosauridae. All of the new information provided data on the affinities of the new-named therizinosauroids. Russell and Dong concluded that they were theropods with unusual features. In 1994, Clark and colleagues redescribed the very complete skull of *Erlikosaurus* and even more theropod traits were found this time. They also validated the synonymy of the Segnosauridae with Therizinosauridae and considered therizinosauroids as maniraptoran dinosaurs. In 1997, Rusell coined the infraorder Therizinosauria in order to contain all segnosaurs. This new infraorder was composed of Therizinosauroidea and the more advanced Therizinosauridae. Consequently, Segnosauria became a synonym of Therizinosauria. Though some uncertainties remained, a small and feathered therizinosauroid from China was described in 1999 by Xu Xing and colleagues: the new genus *Beipiaosaurus*. It confirmed the placement of therizinosaurs among theropods and also their taxonomic place on the Coelurosauria. The discovery also indicated that feathers were highly distributed among theropod dinosaurs.

In 2010, Lindsay Zanno revised the taxonomy of therizinosaurs in extensive detail. She found that many parts on therizinosaur holotype and referred specimens were lost or damaged, and sparse specimens with no overlapping elements were disadvantages when concluding the relationships of the members. Zanno accepted the referral of the specimen IGM 100/45 to *Therizinosaurus* since it matches multiple therizinosaurid traits, but decided not to include the specimen in her taxonomic analysis due to the lack of comparative forelimb remains. She also excluded the supposed ribs that were present on the holotype since they likely came from a different animal and not *Therizinosaurus*. In 2019, Hartman and colleagues also performed a large phylogenetic analysis of Therizinosauria based on the characters provided by Zanno in her revision. They found similar results to Zanno regarding the family Therizinosauridae but this time with the inclusion of more taxa and specimens. The cladogram below shows the placement of *Therizinosaurus* within Therizinosauria according to Hartman and colleagues in 2019: