Yarasuchus is an extinct genus of rauisuchian, a group of predatory and large Triassic archosaurs. It lived during the Anisian stage of the Middle Triassic of India. Being only 2 metres long, is was one of the smallest rauisuchians known. The genus was named and described in 2005 from incomplete fossil material found from the Middle Triassic Yerrapalli Formation, thought to be from two individuals, with one being much more complete and articulated than the other. The type and only species is Y. deccanensis.

 The cervical vertebrae that make up the neck of Yarasuchus are characteristically elongated, while the skull is proportionally small. The genus is also distinguished from other prestosuchids by a delicately built pectoral girdle and a continuous acromion process of the scapula. The neural spines of the vertebrae are high and the paramedian osteoderms are greatly sculptured with a ridge running anteroposteriorly along each one.

 Yarasuchus may have had a facultatively bipedal gait.

 Many other vertebrate remains have been found from the Yerrapalli Formation alongside those of Yarasuchus, and would have coexisted with the genus during the Middle Triassic. Remains of the prolacertiform Pamelaria dolichotrachela have been found in close proximity to those of Yarasuchus. Other vertebrate remains include those of the dipnoan Ceratodus, the actinopterygian Saurichthys, the temnospondyl Parotosuchus, and the dicynodonts Rechnisaurus and Wadiasaurus.

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 Lotosaurus is an is an extinct genus of sail-backed poposauroid known from Hunan Province of central China.

 Lotosaurus is known from the holotype IVPP V 4881 (or possibly V 4880), articulated well-preserved skeleton, and from the referred specimens IVPP V 48013, skull, articulated and disarticulated skeletal remains of at least ten individuals, all came from a monotypic bonebed. All specimens were collected from the Lotosaurus site, from the Batung Formation (or alternatively Xinlingzhen Formation of the Badong Group), dating to the Anisian stage of the early Middle Triassic, about 245-237 million years ago.

 Lotosaurus was 2.5 m (8.2 ft) long and a heavily built quadruped. It was a herbivore, biting off leaves with its toothless jaws. Lotosaurus, like some other members of the Poposauroidea, had a sail on its back. It looked similar to that of Permian pelycosaurs like Dimetrodon and Edaphosaurus, although not as high.

 Lotosaurus was originally thought to be a thecodont, probably related to Ctenosauriscus and other archosaur taxa with elongated neural spines (=Ctenosauriscidae). Many recent cladistic analyses confirmed this affinity. Nesbitt (2007) was the first to suggest that Lotosaurus is more closely related to Shuvosaurus (a shuvosaurid) than to Arizonasaurus (a ctenosauriscid). In his massive revision of archosaurs which included a large cladistic analysis, Sterling J. Nesbitt (2011) found Lotosaurus to be a poposauroid, sister group of the Shuvosauridae, and therefore it is not included in the Ctenosauriscidae. Further studies confirmed these results.

 Lotosaurus was first named by Fa-kui Zhang in 1975 and the type species is Lotosaurus adentus. Lotosaurus was originally placed in its own family, Lotosauridae, which named by Zhang in 1975. The specific name is derived from the Greek a and denta, meaning "toothless", in reference to its toothless beak.

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 Qianosuchus is an extinct genus of aquatic archosaur from the middle Triassic (Anisian) Guanling Formation of Pan County, China. It is represented by two nearly complete skeletons and a crushed skull.

 Qianosuchus mixtus (Li et al. 2006) Middle Triassic ~230 mya)~3+m in length, was derived from a sister to Vjushkovia and was a sister to Yarasuchus and Ticinosuchus.

 Distinct from Yarasuchus, Qianosuchus had shorter cervicals, a broader scapula and deeper chevrons.

 Distinct from Vjushkovia, Qianosuchus had a relatively smaller skull, longer neck, shorter torso, deeper tail and more slender limbs. The rostrum was longer. The naris was located further posteriorly. The notch in the premaxilla/maxilla suture was deeper.

 The dorsal scapula was double the width of the ventral portion.

 The pubis was as long as the ichium. The pedes were more gracile.

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 Shuvosaurus (meaning "Shuvo's lizard") is a genus of beaked reptile from the Late Triassic of Texas. It was described by Sankar Chatterjee in 1993 after it was discovered by his son Shuvo. It was initially interpreted as a Triassic member of the Cretaceous dinosaur family Ornithomimidae. However, the recent discovery of the related Effigia from Ghost Ranch shows that Shuvosaurus is more closely related to crocodilians, and that similarities between this animal and ornithomimids result from convergent evolution. Additionally, this discovery demonstrated that the taxon Chatterjeea was synonymous with Shuvosaurus.

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 Effigia was an archosaur that lived in what is now New Mexico. The 2 meter (6 ft) fossil was collected by Edwin H. Colbert in blocks of rock from the Ghost Ranch Quarry, which were excavated in 1947 and 1948. However, Colbert did not think any large vertebrates besides basal theropod dinosaurs were present in the quarry and as such did not even open the jackets of most of the blocks that were returned to the American Museum of Natural History.

 The fossil was rediscovered in January 2006 by graduate student Sterling Nesbitt at the American Museum of Natural History. Nesbitt was opening jackets of blocks in order to find new specimens of Coelophysis. Upon finding the remains of Effigia, he instantly recognized this was not a dinosaur and proceeded to track down the rest of the blocks from that area of the quarry. Nesbitt and Mark Norell, curator at the museum, named it Effigia okeeffeae in January 2006 after Georgia O'Keeffe, who spent many years at Ghost Ranch (her ashes are scattered there).

 Effigia is remarkable for its extreme similarity to ornithomimid dinosaurs. Nesbitt, in 2007, showed that Effigia was very similar to Shuvosaurus, and is definitely a member of the crurotarsan group Suchia (in the line leading towards modern crocodilians), and that its similarity to ornithomimids represents a case of "extreme" convergent evolution. Nesbitt also demonstrated that Shuvosaurus was the same animal as Chatterjeea, and that it belonged to an exclusive clade containing closely related suchians such as Shuvosaurus and Poposaurus (Poposauridae). Within this group, Effigia forms an even more exclusive clade with Shuvosaurus and the South American Sillosuchus (Shuvosaurinae). In 2007, Lucas and others suggested "Effigia" was synonymous with "Shuvosaurus" and used the new combination "Shuvosaurus okeeffeae" for the animal.

 Shuvosauridae is an extinct family of theropod-like pseudosuchian within the clade Poposauroidea. Shuvosaurids existed in North (USA) and South America (Argentina) during the Late Triassic period (late Carnian to Rhaetian stages). Shuvosauridae was named by Sankar Chatterjee in 1993 to include the genus Shuvosaurus.

 In a 2007 study Chatterjeea was demonstrated to be a junior synonym of Shuvosaurus, and the therein cladistic analysis found that Shuvosaurus, Effigia and Sillosuchus all form a closely related group. However, this group was left nameless, and simply referred to as Group Y. However, in accordance with ICZN rules of naming priority Shuvosauridae has priority over Chatterjeeidae (Shuvosauridae being named in 1993, while Chatterjeeidae was named in 1995). In 2011, Sterling J. Nesbitt proposed a new definition to this clade: "The least inclusive clade containing Shuvosaurus inexpectatus Chatterjee, 1993, and Sillosuchus longicervix Alcober and Parrish, 1997".

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 Poposaurus is an extinct genus of pseudosuchian archosaur from the Late Triassic of the southwestern United States. It belongs to the clade Poposauroidea, an unusual group of Triassic pseudosuchians that includes sail-backed, beaked, and aquatic forms. Fossils have been found in Wyoming, Utah, Arizona, and Texas. Except for the skull, most parts of the skeleton are known. The type species, P. gracilis, was described by M. G. Mehl in 1915. A second species, P. langstoni, was originally the type species of the genus Lythrosuchus. Since it was first described, Poposaurus has been variously classified as a dinosaur, a phytosaur, and a "rauisuchian".

 Like theropod dinosaurs, Poposaurus was an obligate biped, meaning that it walked on two legs rather than four. However, as a pseudosuchian, it is more closely related to living crocodilians than to dinosaurs. Poposaurus is thought to have evolved this form of locomotion independently, possibly from early archosaurs' ability to high walk.

 Poposaurus was about 4 metres (13 ft) long, with the tail comprising about half the body length. It is estimated to have weighed around 60 to 75 kilograms (130 to 170 lb), with the largest individuals reaching 90 to 100 kilograms (200 to 220 lb). The body of Poposaurus is laterally compressed, with a long and narrow hip structure. The pubis and ischium are elongated. The end of the pubis forms a distinct hook that is unique to Poposaurus and a few other early pseudosuchians. Poposaurus has five sacral vertebrae connecting the spine to the hip, three more than most early archosaurs. The hind legs are about twice as long as the arms and placed close together. Five digits are present on the foot, but the fifth is reduced to a small splint of bone next to the metatarsals. The middle three toes are well-developed, giving the foot a tridactyl appearance. The calcaneum bone extends far from the ankle to form a distinct heel.

 Poposaurus is a member of the family Poposauridae, part of the larger pseudosuchian group Poposauroidea. It is closely related to other Triassic pseudosuchians like ctenosauriscids and shuvosaurids. Like Poposaurus, shuvosaurids were bipedal. When the specimen YPM VP 057100 was described by Gauthier et al. in 2011, Poposaurus was included in a phylogenetic analysis. Poposaurus was placed within Poposauroidea as the sister taxon to the large-bodied herbivorous Lotosaurus and the shuvosaurids. This means that Poposaurus is more closely related to Lotosaurus and shuvosaurids than it is to any other pseudosuchian. The analysis found ctenosauriscids and the aquatic Qianosuchus to be successively more basal poposauroids.

  Poposauridae is a family of large (around 2.5 to 5 meters long) carnivorous archosaurs which lived alongside dinosaurs during the Late Triassic. Poposaurids are known from fossil remains from North and South America. While originally believed to be theropod dinosaurs (they mirrored the theropods in a number of respects, such as features of the skull and bipedal locomotion), cladistic analysis has shown them to be of closer relation to crocodiles.

 An early cladistic analysis of crocodylotarsan archosaurs included Poposaurus, Postosuchus, Teratosaurus, and Bromsgroveia within Poposauridae. However, later studies found Teratosaurus to be a rauisuchid. All recent phylogenetic analyses place Postosuchus either as a rauisuchid or a prestosuchid.

 Найдены останки двуногих крокодилов (прим. - на самом деле, попозавры - это не крокодилы, а представители родственной предкам крокодилов группы паракрокодиломорфов) триасового периода, сообщает «Информнаука» со ссылкой на публикацию в журнале Bulletin of the Peabody Museum of Natural History.

 Древняя рептилия Poposaurus gracilis (в переводе с латыни gracilis означает «изящный, грациозный») обладала маленькими передними конечностями, мощными задними и длинным, сужающимся хвостом, позволявшим ей балансировать при ходьбе или беге по ландшафтам позднего триасового периода — 225 миллионов лет назад. При таком внешнем виде было бы весьма заманчивым отнести данную рептилию к динозаврам. Однако этот архозавр являлся представителем древней ветви крокодилов и, как установили американские палеонтологи, передвигался на двух ногах. Подробности исследования такого любопытного способа ходьбы попозавров, опубликованные в последнем номере, также дают некоторые объяснения, почему динозавры в мезозойскую эру повсеместно доминировали над остальными современниками.

 Попозавр, описанный впервые более века назад, относится к равизухиям — части вымершей ветви рептилий, включавшей в себя разнообразных предков крокодилов и их ближайших родственников. До недавнего времени считалось, что попозавр и все остальные равизухии передвигались на четырёх конечностях. Тем не менее уже тогда было показано, что они отличались от крокодилов строением обоих поясов конечностей. Их лапы располагались не по бокам от туловища, как у современных крокодилов, а вертикально под ним, как у современных млекопитающих. Такое расположение конечностей делало их более эффективными при ходьбе и беге.

 В 2006 году палеонтологи Марк Норелл и один из авторов данной работы Стерлинг Несбитт из Американского музея естественной истории в Нью-Йорке описали двуногую «прямоходящую» равизухию, названную ими Effigia okeeffaea. У эффигии не было зубов, и предположительно она была травоядным архозавром.

 Исследованный учёными скелет Poposaurus gracilis был обнаружен в отложениях триасового месторождения Чинл, в районе Американского национального монумента Гранд Стеркейс-Эскаланте, на юге штата Юта. Длина попозавра составляла примерно 4,5 метра. Острые изогнутые зубы указывают на явную принадлежность рептилии к хищникам. Анализ анатомических особенностей таза и задних конечностей убедительно показал, что попозавры ходили прямо и их конечности располагались близко к средней линии тела, а способ их передвижения не имел ничего общего с тем, как перемещаются современные крокодилы, а походил на тот, который был распространен у динозавров. Попозавр пополнил список древних двуногих крокодиловых, которые теперь рассматриваются не как эволюционная случайность, а как специализированная группа рептилий, отделившаяся от предковой ветви приблизительно в то же время, что и ранние динозавры.

 Открытие двуногих родственников крокодила с «динозавровым» строением конечностей некоторым образом объясняет, почему динозавры добились господствующего положения к концу триаса. Палеонтологи считают, что анатомические особенности динозавров позволяли им передвигаться быстрее и эффективнее по сравнению с обычным «крокодиловым» способом других рептилий. Но почему равизухии, независимо развившие прямохождение в ходе своей эволюции, вымерли, в то время как у динозавров на тот момент продолжилось процветание, пока остается тайной.

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 Xilousuchus is an extinct genus of poposauroid from lower Triassic (Olenekian stage) deposits of Fugu County of northeastern Shanxi Province, China. It is known from the holotype, IVPP V 6026, a single well-preserved partial skeleton including the skull. It was found from the Heshanggou Formation of the Ordos Basin, Hazhen commune. It was first named by Xiao-Chun Wu in 1981 and the type species is Xilousuchus sapingensis. Wu (1981) referred Xilousuchus to the Proterosuchia. Gower and Sennikov (1996) found it to be an erythrosuchian based strictly on the braincase. A more detailed re-description of the genus was provided by Nesbitt et al. (2010) and found poposauroid affinities. In his massive revision of archosaurs which included a large cladistic analysis, Sterling J. Nesbitt (2011) found Xilousuchus to be a poposauroid which is most closely related to Arizonasaurus. Xilousuchus is the oldest archosaur to date, although Ctenosauriscus and Vytshegdosuchus might be even older by less than one million year. Since Xilousuchus is a suchian archosaur, its early age suggests that most of the major groups of archosaurs (ornithodirans, ornithosuchids, aetosaurs, and paracrocodylomorphs) developed by the Early Triassic, soon after the appearance of the first archosaur.

 Ископаемое существо, найденное в Китае в 1970-х и считавшееся дальним родственником птиц и крокодилов, оказалось членом генеалогического древа крокодилов на том этапе, когда они уже отделились от птиц.

 Единственный образец Xilousuchus sapingensis теперь классифицируется как архозавр.

 Стерлинг Несбитт из Университета штата Вашингтон (США) датирует вид ранним триасом (252–247 млн лет назад). Это значит, что он жил всего несколько геологических минут спустя после крупнейшего массового вымирания в истории Земли, случившегося в конце пермского периода (погибли 95% морских и 70% сухопутных видов). «В поисках происхождения архозавров мы всё ближе и ближе к границе перми и триаса», — отмечает специалист.

 Исследование может обострить дискуссию о том, существовали ли архозавры до биологической катастрофы или же в конце перми жили их предшественники, а сами архозавры стали продуктом восстановления фауны после вымирания.

 X. sapingensis — череп и 10 позвонков — был найден в формировании Хэшангоу в северном Китае в отложениях, которые датируются не только началом и серединой триаса (252–230 млн лет назад), но и периодом до массового вымирания.

 Ископаемое первоначально классифицировали как archosauriform, то есть родственник архозавров, а не истинный архозавр, но это было до открытия более полных образцов ранних архозавров из других частей триасового периода. Исследователи заново изучили кости образца, сравнив их с останками ближайших родственников архозавров, и нашли серьёзные отличия от всех archosauriformes.

 В частности кости на кончике челюсти, где должны располагаться зубы, оказались загнуты вниз не так сильно, как было впервые описано в 1980-х годах. Обнаружено также, что нервные шипы шеи формировали переднюю часть паруса так же, как у другого древнего архозавра под названием Arizonasaurus.

 Главный вывод заключается в том, что предки птиц и крокодилов разделились раньше, чем принято было ранее считать.

 Результаты исследования опубликованы в журнале Earth and Environmental Science Transactions.

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 Ctenosauriscus is an extinct genus of sail-backed poposauroid archosaur from Early Triassic deposits of Lower Saxony in northern Germany. It gives its name to the family Ctenosauriscidae, which includes other sail-backed poposauroids such as Arizonasaurus. Fossils have been found in latest Olenekian deposits around 247.5-247.2 million years old, making it one of the first known archosaurs.

 The most prominent feature of Ctenosauriscus is its sail-like back, formed from elongated neural spines of the dorsal and cervical vertebrae. These spines curve slightly forward at the front of the sail and slightly backward at the back of the sail. Although other poposauroids like Lotosaurus and the ctenosauriscids Hypselorhachis and Xilousuchus also have elongated spines, the sail of Ctenosauriscus is one of the largest in the group. Among ctenosauriscids, Ctenosauriscus is most similar to Arizonasaurus from the Middle Triassic of the southwestern United States. Both of these ctenosauriscids have elongated vertebrae spines up to 12 times the height of the bodies of the vertebrae. The ends of the spines are wider in Ctenosauriscus, and Ctenosauriscus also has larger projections on the centra of the dorsal vertebrae. Hypselorhachis also has neural spines that are widened at the end, but they are shorter than those of Ctenosauriscus. Lotosaurus from the Middle Triassic of China also has elongate spines, but they are straighter, broader, and much shorter than those of Ctenosauriscus.

 A 1998 study proposed that Ctenosauriscus was bipedal and that its elongated neural spines served to absorb the forces exerted from walking on two legs. Although limb bones are unknown, the study found that forces on the tips of the spines were focused on a point below the spinal column, hypothesized to be the knee joint. In the 2011 redescription of Ctenosauriscus, the authors rejected this idea because for forces on the spine to meet at the knee joint, muscles would have to form a direct connection between the knee and the back. Forces exerted from movement travel from the hind legs to the hip and sacral vertebrae, not the dorsal vertebrae. The sail of Ctenosauriscus would also have shifted its center of weight toward the front of the body, making bipedal locomotion difficult or impossible.

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 Arizonasaurus was a ctenosauriscid archosaur from the Middle Triassic (240 million years ago). Arizonasaurus is found in the Middle Triassic Moenkopi Formation of northern Arizona. A fairly complete skeleton was found in 2002 by Sterling Nesbitt. The taxon has a large sailback formed by elongate neural spines of the vertebrae. The type species, Arizonasaurus babbitti, was named by Samuel Paul Welles in 1947. It superficially resembles the sail-backed synapsids Dimetrodon and Edaphosaurus, which lived millions of years earlier during the Late Pennsylvanian and Permian.

 Ctenosauriscidae is an extinct family of pseudosuchian archosaurs within the clade Poposauroidea. Ctenosauriscids existed in Africa, Asia, Europe and North America during the Early Triassic to the Middle Triassic period (latest Olenekian to Anisian stages). All species had large "sails" on their backs. Ctenosauriscids are among the earliest archosaurs and represent the first global radiation of the group.

 Poposauroidea is a clade of rauisuchians. It includes poposaurids, shuvosaurids, and ctenosauriscids, but excludes the large predatory quadrupedal rauisuchians such as rauisuchids and prestosuchids. Although it was first formally defined in 2007, the term has been used for many years. The group has been referred to as Poposauridae by some authors, although this name is often used more narrowly to refer to the family that includes Poposaurus and its close relatives.

 Rauisuchia is a group of predatory and mostly large (often 4 to 6 meters) Triassic archosaurs. As a clade, Rauisuchia includes these Triassic forms and all crocodylomorphs, which are descendants of Triassic rauisuchians. The group in its traditional sense is paraphyletic, because it does not include crocodylomorph descendants. To designate it as an informal group in scientific literature, the name in its traditional sense is often enclosed in quotation marks.

 Both José Bonaparte and Michael Benton argue that rauisuchians such as Saurosuchus developed an erect stance independently of, and different from that of dinosaurs, by means of having the femur vertical and angling the acetabulum ventrally, rather than having an angled neck or curve in the femur. This has been referred to as the pillar-erect posture.

 The erect gait indicates that these animals were clearly active, agile predators, with locomotor superiority over the kannemeyeriid dicynodonts and abundant rhynchosaurs on which they fed. They were successful animals, the largest with skulls up to a meter or more in length, and continued right until the end of the Triassic, when, along with many other large archosaurs, they were killed off by the end Triassic extinction event. With their demise, theropod dinosaurs were able to emerge as the sole large terrestrial predators. Meat-eating dinosaur footprints suddenly increase in size at the start of the Jurassic, when rauisuchians are absent.

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