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27.12.2015 22:27 - Encyclopedia Largest prehistoric animals Vol.1 Vertebrates part3 Dinosaurs ch.1 Theropods?Strange giants-Deinocheiridae and Therizinosauridae
Автор: valentint Категория: Забавление   
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Deinocheiridae
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1. Ornithomimus 2. Struthiomimus 3. Deinocheirus 4. Gallimimus 5. Anserimimus

Deinocheiridae
is a family of ornithomimosaurian dinosaurs, living in Asia from the Albian until the Maastrichtian. The family was originally named by Halszka Osmуlska and Roniewicz in 1970, including only the type genus Deinocheirus. In a 2014 study by Yuong-Nam Lee and colleagues and published in the journal Nature, it was found that Deinocheiridae was a valid family. Lee et al. found that based on a new phylogenetic analysis including the recently discovered complete skeletons of Deinocheirus, the type genus, as well as Garudimimus and Beishanlong, could be placed as a successive group, with Beishanlong as the most primitive and Deinocheirus as most derived. The family Garudimimidae, named in 1981 by Rinchen Barsbold, is now a junior synonym of Deinocheiridae as the latter family includes the type genus of the former. The group existed from 115 to 69 million years ago, with Beishanlong living from 115 to 100 mya, Garudimimus living from 98 to 83 mya, and Deinocheirus living from 71 to 69 mya.


Deinocheirus
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Deinocheirus
is a genus of large ornithomimosaur (ostrich dinosaur) that lived during the Late Cretaceous around 70 million years ago. In 1965, a pair of large arms, shoulder girdles, and a few other bones of a new dinosaur were first discovered in the Nemegt Formation of Mongolia. In 1970, this specimen became the holotype of the only species within the genus, Deinocheirus mirificus; the genus name is Greek for "horrible hand". No further remains were discovered for almost fifty years, and its nature remained a mystery. Two more complete specimens were described in 2014, which shed light on many aspects of the animal. Parts of these new specimens had been looted from Mongolia some years before, but were repatriated in 2014.
Deinocheirus was an unusual ornithomimosaur, the largest of the clade at 11 m (36 ft) long, and weighing 6.36 t (14,000 lb). Though it was a bulky animal, it had many hollow bones which saved weight. The arms were among the largest of any bipedal dinosaurs at 2.4 m (7.9 ft) long, with large, blunt claws on its three-fingered hands. The legs were relatively short, and bore blunt claws. Its vertebrae had tall neural spines that formed a "sail" along its back. The tail ended in pygostyle-like vertebrae, which indicate the presence of a fan of feathers. The skull was 1.024 m (3.36 ft) long, with a wide bill and a deep lower jaw, similar to those of hadrosaurs.
The classification of  Deinocheirus was long uncertain, and it was initially placed in the theropod group carnosauria, but similarities with ornithomimosaurians were soon noted. After more complete remains were found, Deinocheirus was shown to be a primitive ornithomimosaurian, most closely related to the smaller genera Garudimimus and Beishanlong, together forming the family Deinocheiridae. Members of this group were not adapted for speed, unlike other ornithomimosaurs. Deinocheirus is thought to have been omnivorous; its skull shape indicates a diet of plants, fish scales were found in association with one specimen and gastroliths were also present in the stomach region of the specimen. The large claws may have been used for digging and gathering plants. Bite marks on Deinocheirus bones have been attributed to the tyrannosaurid Tarbosaurus.
Deinocheirus was the largest ornithomimosaurian (ostrich dinosaur); the largest known specimen measured up to 11 m (36 ft) long, with an estimated weight of 6.36 t (14,000 lb). The two other known specimens are smaller, the holotype being 94% as big while the smallest, a subadult, only 74% as big.[1] When only the incomplete holotype arms were known, various sizes were extrapolated from them by different methods. A 2010 study estimated the hip height of Deinocheirus to be 3.3–3.6 m (11–12 ft).The weight had previously been estimated between 2 tonnes (4,400 lb) to 12 tonnes (26,000 lb). Enormous sizes were also suggested by comparing the arms with those of tyrannosaurs, even though members of that group have very small arms in proportion to their body size.
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Deinocheirus and Therizinosaurus possessed the longest forelimbs known for any bipedal dinosaurs.The holotype forelimbs measure 2.4 m (7.9 ft) long — the humerus (upper arm bone) is 93.8 cm (36.9 in), the ulna 68.8 cm (27.1 in), and the hand is 77 cm (30 in) — including the 19.6 cm (7.7 in) long recurved claws. Each scapulocoracoid of the shoulder girdle has a length of 1.53 m (5.0 ft). Each half of the paired ceratobranchialia measure 42 cm (17 in). The shoulder-blade was long and narrow, and the deltopectoralis crest was pronounced and triangular. The upper arm (humerus) was relatively slender, and only slightly longer than the hand. The ulna and radius (lower arm bones) were elongate and not firmly connected to each other in a syndesmosis. The metacarpus was long compared to the fingers. The three fingers were about equal in length, the first being the stoutest and the second the longest. Various rough areas and impressions on the forelimbs indicate the presence of powerful muscles. Most articular surfaces of the arm bones were deeply furrowed, indicating that the animal had thick pads of cartilage between the joints. Though the arms of Deinocheirus were large, the ratio between them and the shoulder girdle was less than that of the smaller ornithomimosaur Ornithomimus.The arm bones of Deinocheirus were similar in proportions to those of the small theropod Compsognathus.The wishbone (furcula), an element not known from any other ornithomimosaurs, was U-shaped. The hindlimbs were relatively short, and the thigh bone (femur) was longer than the shin bone (tibia), as is common for large animals. The metatarsus was short and not arctometatarsalian, as in most other theropods. The claw bones of the feet were blunt and broad-tipped instead of tapered, unlike other theropods, but resembled the unguals of large ornithischian dinosaurs. The proportions of the toe bones resembled those of tyrannosaurs, due to the large weight they had to bear.
Though Deinocheirus was a bulky animal, its dorsal ribs were tall and relatively straight, indicating that the body was narrow.The ten neck vertebrae were low and long, and progressively shorter backwards from the skull. This resulted in a more S-curved neck than seen in other ornithomimosaurs, due to the larger skull. The neural spines of the twelve back vertebrae became increasingly longer from front to back, the last one being 8.5 times the height of the centrum part. This is almost the same as the highest ratio in the neural spines of the theropod Spinosaurus. The neural spines had a system of ligaments, which were probably used to support the abdomen by attaching to the hips and hind legs.Together, the neural spines formed a tall "sail" along the lower back, hips, and base of the tail, somewhat similar to that of Spinosaurus.
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All the vertebrae were highly pneumatised by air sacs, except for the atlas bone and the hindmost tail vertebrae, and were connected to the respiratory system. The back vertebrae were as pneumatised as those of sauropod dinosaurs, and had an extensive system of depressions. These adaptations may be correlated with gigantism, as they reduce weight. The six vertebrae of the sacrum were also tall and pneumatised, and all but the first one were fused together at the top, their neural spines forming a neural plate. The ilium, the top hip bone, was also partially pneumatised close to the sacral vertebrae. Part of the pelvis was hypertrophied (enlarged) compared to other ornithomimosaurs, to support the weight of the animal with strong muscle attachments. The front hip bones tilted upwards in life. The tail of Deinocheirus ended in at least two fused vertebrae, which were described as similar to the pygostyle of oviraptorosaurian and therizinosauroid theropods. Ornithomimosaurs are known to have had pennaceous feathers, so this feature suggests that they might have had a fan of feathers at the tail end.
The only known skull, belonging to the largest specimen, measures 1.024 m (3.36 ft) from the premaxilla at the front to the back of the occipital condyle. The widest part of the skull behind the eyes is only 23 cm (9.1 in) wide in comparison. The skull was similar to those of other ornithomimosaurs in being low and narrow, but differed in that the snout was more elongated. The skull bone walls were rather thin, about 6 mm (0.24 in). It had a rounded, flattened beak, which would have been covered by keratin in life. The nostrils were turned upwards, and the nasal bone was a narrow strap that extended up above the eye sockets. The outer diameter of the sclerotic rings in the eyes was small, 8.4 cm (3.3 in), compared to the size of the skull. The lower temporal fenestrae, openings behind the eyes, were partially closed off by the jugal bones, similar to Gallimimus. The jaws were toothless and down-turned, and the lower jaw was very massive and deep compared to the slender and low upper jaw. The relative size of the lower jaw was closer to that of tyrannosaurids than to other ornithomimosaurs. The snout was spatulate (flared outwards to the sides) and 25 cm (9.8 in) wide, which is wider than the skull roof.This shape is similar to the snout of duck-billed hadrosaurids.


Therizinosauridae
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1. Segnosaurus 2. Therizinosaurus 3. Alxasaurus 4. Erlikosaurus 5. Eshanosaurus
Therizinosauridae ("reaper lizards") is a family of theropod dinosaurs whose fossil remains have been dated to the Mid-to-Late Cretaceous period (100 to 70 mya). Therizinosaur fossils have been found in Early through Late Cretaceous deposits in Mongolia, the People"s Republic of China, western North America and possibly Australia.Various features of the forelimbs, skull and pelvis unite these finds as both theropods and as maniraptorans, close relatives to birds.
Therizinosauridae was named after the large, claw-bearing ungual found on the manus of members in the group. This feature has led to little insight about the ecology of the family, and the purpose of the claw remains unknown.Other notable aspects of the physiology of these animals include a modified pelvis, robust hind-limbs, and a highly derived, nearly avian inner-ear.Moreover, the larger superfamily of Therizinosauroidea is believed to be the earliest group in which simple feathers have been documented.
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The family Therizinosauridae contains Nothronychus, Erlicosaurus, Neimongosaurus, Therizinosaurus, and Segnosaurus.However, some studies also place Erliansaurus and Erlikosaurus within the grouping, Therizinosauridae, along with Alxasauridae, and a handful of partially-classified genera, constitute the superfamily of Therizinosauroidea. Finally, Therizinosauroidea falls within the higher clade of Therizinosauria, which also includes Jianchangosaurus and Falcarius according to the latest phylogeny.

Research into therizinosaurids has also focused on uncovering more about the unique ecology and paleobiology of the family. A fair portion of modern research has concentrated on the feeding-patterns of these reptiles, as they are considered to be the best regarded candidate for the emergence of herbivory within Theropoda.While many closely related taxa are carnivorous, it is thought that the members of Therizinosauroidea, including Therizinosauridae, diverged and adopted either an herbivorous or omnivorous lifestyle.
The current scientific consensus is that therizinosaurids evolved from small, bird-like maniraptorans, and thus they fall within the coelurosaurian clade called Maniraptora. Most studies have concluded that within Maniraptora, Therizinosaurians were the first of five major groups to diverge.


Therizinosaurus
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Therizinosaurus is a genus of very large theropod dinosaurs. Therizinosaurus comprises the single species T. cheloniformis, which lived in the late Cretaceous Period (late Campanian-early Maastrichtian stages, around 70 million years ago), and was one of the last and largest representatives of its unique group, the Therizinosauria. Fossils of this species were first discovered in Mongolia and were originally thought to belong to a turtle-like reptile (hence the species name, T. cheloniformis – "turtle-formed"). It is known only from a few bones, including gigantic hand claws, from which it gets its name.

Though the fossil remains of Therizinosaurus are incomplete, inferences can be made about their physical characteristics based on related therizinosaurids. Like other members of their family, Therizinosaurus probably had small skulls atop long necks, with bipedal gaits and heavy, deep, broad bodies (as evidenced by the wide pelvis of other therizinosaurids). Their forelimbs may have reached lengths of up to 2.5 metres (8.2 feet) or even 3.5 metres (11.5 feet) in the largest known specimen. Their hindlimbs ended in four weight-bearing toes, unlike other theropod groups, in which the first toe was reduced to a dewclaw. In 2010 Gregory S. Paul estimated the maximum size of Therizinosaurus at 10 metres (33 ft) in length and five tonnes in weight. They are the largest therizinosaurs known, and the largest known maniraptorans.
The most distinctive feature of Therizinosaurus was the presence of gigantic claws on each of the three digits of their front limbs. These were common among therizinosaurs but especially large in Therizinosaurus, and while the largest claw specimens are incomplete, they probably reached just under 1 metre (3.3 ft) in length. The claws are the longest known from any animal. The claws were relatively straight, only gradually tapering into a point, and extremely narrow, transversely flattened.
The feeding habits of Therizinosaurus are unknown since no skull material has ever been found that could indicate their diet. However, like other therizinosaurs, they were probably primarily herbivorous.
In 1954 Therizinosaurus was assigned by Maleev to the Therizinosauridae, which were seen by him as a unique central Asian family of gigantic sea-turtles.Later the Therizinosauridae were identified with the Segnosauridae, the former name having priority. Relationships within the Therizinosauridae are difficult to determine, due to the paucity of remains known from Therizinosaurus itself.








 

 




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