Xianglong (meaning "flying lizard" in Chinese) is a genus of Cretaceous lizard discovered in the Liaoning Province of China. It is known from LPM 000666, a single complete skeleton with skin impressions. The specimen comes from the Barremian-age Lower Cretaceous Yixian Formation, near Yizhou. The most notable feature about Xianglong is its bizarre oversized ribs, eight on each side, which were attached to a membrane of body tissue and allowed the lizard to glide. It was an acrodont lizard, and a cladistic analysis indicates it was grouped with iguanians such as agamines, chamaeleonids, and leiolepidines.

 The fossil specimen found was 15.5 centimetres (6.1 in) long, 9.5 centimetres (3.7 in) of which was tail, but the describers say it was a juvenile. So far this is the only known fossil gliding lizard, though there are other unrelated animals that also use their ribs to glide.

 Xianglong is one of the few creatures that glide using their ribs. Other creatures, such as the flying squirrel and the Malabar Flying Frog, Rhacophorus malabaricus, have a different membrane attachment, toes to toes or limb to limb. Two creatures use the same way to glide, the present day Flying Lizard (genus Draco, Latin for dragon) and Triassic fossil reptiles such as Kuehneosaurus, but the Triassic look-alikes lived over 100 million years before Xianglong. Despite the 11-centimeter(4.3 in) "rib-span", the lizard might have been quite agile in the air, possibly to escape the feathered dinosaurs that coexisted with it.

 Xianglong had slightly curved claws, indicating that it was arboreal. Of course, it needed to be in order to get in its "gliding mode".

 Xu Xing, a Chinese paleontologist and one of the describers of Xianglong, states that it is possible Xianlong could have glided as much as half a football field, much farther than that of the modern Draco.

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 Dinilysia (meaning "terrible ilysia") is an extinct genus of snake from the Late Cretaceous (Coniacian) of South America. The snake reached a length of 6-10 feet (1.8-3 meters) and preyed on smaller animals. The shape of the animal's skull does not support the suggestion that snakes were burrowers during their ancestry; it is clear that Dinilysia was terrestrial.

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 Sanajeh (meaning "ancient gape" in Sanskrit) is a genus of late Cretaceous madtsoiid snake from western India. A recently described fossil from the Lameta Formation has been found coiled around an egg and an adjacent skeleton of a 50 cm long sauropod dinosaur hatchling. This suggests that the snake preyed on hatchling sauropods at nesting sites.

 The holotype specimen, known as GSI/GC/2901–2906, consists of a nearly complete skull and lower jaws, and 72 precloacal vertebrae and ribs preserved in five articulated sections. It was found from Maastrichtian-age calcareous sandstones outcropping in the village of Dholi Dungri in Gujarat.

 Sanajeh was around 3.5 metres (11 ft) in length based on the length of the skull, which is 95 millimetres (3.7 in). On the side of the skull there is an opening called the juxtastapedial recess, which is characteristically rectangular. The juxtastapedial recess would have contained cranial nerves associated with the ear, while another opening located in front of the recess, the trigeminal foramen, housed cranial nerves associated with the jaws. The jaw joint of Sanajeh is located to the side of the posterior margin of the braincase, which is characteristic of basal snakes. A sagittal crest runs along the ventral surface of the braincase and served as an attachment for protractor pterygoidei muscles that moved the toothed bones of the palate.

 Articulations between the vertebrae are well developed in Sanajeh in a similar way to other madtsoiids and the genus Najash. The neural spines are thin and angled posteriorly. In Sanajeh, the synapophyses, or rib articulations, extend outward past the margins of the prezygapophyses. This is a characteristic of all madtsoiids.

 Sanajeh is a member of the Madtsoiidae, an extinct family of snakes that includes the Australian genera Wonambi and Yurlunggur.

 Like many early snakes, Sanajeh did not have the wide gape seen in boids, pythons, and caenophidians. Therefore, it could not consume prey as large as that which many modern snakes can. Living snakes that have narrow gapes, including uropeltids, Anomochilus, Cylindrophis, and Anilius, have diets that are limited to smaller animals such as ants, termite larvae, annelids, and amphisbaenians and caecilians. The short supratemporal and broad, short quadrate indicate that the oral gape of Sanajeh was narrow. The gape is thought to have been similar to that of the extant genus Xenopeltis. However, the presence of strong m. protractor pterygoidei muscles inferred from the sagittal crest of Sanajeh indicates that it was able to manipulate prey in its mouth like modern macrostomatans. The intramandibular joint was able to flex greatly, which would allow for the consumption of larger prey. The presence of these features in Sanajeh shows that increased oral kinesis (movement of the mouth) and intraoral mobility (the ability to move the bones of the palate) preceded the development of wide gapes in snakes. Therefore, reduced cranial kinesis in basal living snakes may be a fossorial adaptation rather than the retention of a plesiomorphic trait.

 The holotype of Sanajeh was found in association with sauropod eggs belonging to the oospecies Megaloolithus dhoridungriensis and one incompletely preserved sauropod hatchling, likely a titanosaur. The snake was coiled around a crushed egg, which the hatchling may have exited from. The eggs were laid in a nest structure that was not preserved, but was likely covered in loose sediment or vegetation based on the porosity of the eggs. The rigid eggs were probably too large for Sanajeh to consume, but the snake would have been able to break an egg open and consume its contents in a way similar to the living Loxocemus. Sanajeh is likely to have had a nest-plundering feeding strategy, and it is possible that the snake consumed a large variety of prey items including the eggs of theropods and smaller reptiles, which are common in the Lameta Formation.

 Accelerated growth rates and large numbers of hatchlings would have enabled titanosaurs such as Isisaurus and Jainosaurus to overcome the losses of predation by animals such as Sanajeh. Titanosaurs would have been free of the risk of predation by their first year as a result of their rapid growth rate. The size of adult titanosaurs, which could be 20–25 metres (66–82 ft) in length, would have deterred nearly all predators.

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 Madtsoia is an extinct genus of madtsoiid snake. It is known from the Eocene of Argentina (M. bai), the Paleocene of Brazil (M. camposi), the Late Cretaceous (Campanian) of Spain (M. laurasiae), the Late Cretaceous of India (M. pisdurensis), and the Late Cretaceous (Campanian-Maastrichtian) of Madagascar and possibly Niger (M. madagascariensis).

 As extinct snakes go, Madtsoia is less important as an individual genus than as the eponymous representative of the family of snake ancestors known as madtsoiidae, which had a worldwide distribution from the late Cretaceous period all the way up to the Pleistocene epoch, about two million years ago. However, as you can surmise from this snake's unusually wide geographic and temporal distribution (its various species span about 90 million years) not to mention the fact that it's represented in the fossil record almost exclusively by vertebrae. Paleontologists are far from sorting out the evolutionary relationships of Madtsoia and the madtsoiida and modern snakes. Other madtsoid snakes, at least provisionally, include Gigantophis, Sanajeh and most controversially the two-legged snake ancestor Najash .

 Madtsoiidae are an extinct group of mostly Gondwanan snakes with a fossil record extending from early Cenomanian (Upper Cretaceous) to late Pleistocene strata located in South America, Africa, India, Australia and Southern Europe. Madtsoiid snakes include very primitive snakes, which like extant boas and pythons would likely dispatch their prey by constriction, such as Gigantophis, one of the longest snakes known at an estimated 10.7 meters, and the Australian Aboriginal mythology-named Wonambi and Yurlunggur. As a grouping of basal forms the composition and even the validity of Madtsoiidae is in a state of flux as new pertinent finds are described.

 Madtsoiidae was first classified as a subfamily of Boidae, Madtsoiinae, in Hoffstetter (1961a). Further study and new finds allowed ranking the group as a distinct family in Linnaean systems. With the recent use of cladistics to unravel phylogeny, various analyses have posited Madtsoiidae as a likely clade within Serpentes, or possible paraphyletic stem group outside Serpentes and within a more inclusive Ophidia. Madtsoiid snakes ranged in size from less than 1 m (estimated total length) to over 9 m, and are thought to have been constrictors analogous to modern pythons and boas, but with more primitive jaw structures less highly adapted for swallowing large prey. There are specific anatomical features that diagnose members of this family, such as the presence of hypapophyses only in anterior trunk, that the middle and posterior trunk vertebrae possess a moderately or well-developed haemal keel, except for a few near the cloacal region, often with short laterally paired projections on the posterior part of the keel. Also, all trunk and caudal vertebrae have at least a parazygantral foramen, sometimes several of them, located in a more or less distinct fossa that is lateral to each zygantral facet. Addition features are the prezygapophyseal processes' absence while the paracotylar foramina are present and that the diapophyses are relatively wide, exceeding width across prezygapophyses at least in the posterior trunk vertebrae. (Scanlon 2005)

 Like most fossil snakes the majority of madtsoiids are known only from isolated vertebrae, but several (Madtsoia bai, M. camposi, Wonambi naracoortensis, Nanowana spp., unnamed Yurlunggur spp., Najash rionegrina) have associated or articulated parts of skeletons. Of the genera listed below, all have been referred to Madtsoiidae in all recent classifications except Najash rionegrina, which is included here based on diagnostic vertebral characters described by Apesteguía and Zaher (2006). These authors didn't include Najash among madtsoiids because they consider that madtsoiids are a paraphyletic assemblage of basal macrostomatans related to Madtsoia bai and consequently, not related to the Cretaceous alethinophidians from southern continents.

 Rieppel et al. (2002) classified Wonambi naracoortensis within the extant radiation, (crown group), of snakes as Macrostomata incertae sedis, but many of their character state attributions for this species have been criticised or refuted by Scanlon (2005a) and the better-preserved skulls of Yurlunggur sp./spp. have numerous characters apparently more plesiomorphic than any macrostomatans (Scanlon 2006). The partial skull attributed to Najash rionegrina  (Apesteguía and Zaher 2006) resembles that of the non-madtsoiid Dinilysia patagonica, and vertebrae support that they are related. The type material of Najash is the only possible madtsoiid specimen retaining evidence of pelvic and hindlimb elements, which are claimed to be more plesiomorphic than other Cretaceous limbed snakes, such as Pachyrhachis, Haasiophis or Eupodophis, in retaining a sacro-iliac contact and well-developed limbs, with a huge and well-defined trochanter. The sacro iliac contact is perhaps misleadingly described by Apesteguía and Zaher as unique possession of a sacrum, whereas it has rarely been questioned that the cloacal vertebrae in snakes are homologous to the sacrals of limbed squamates (i.e. the sacrum is present but has lost contact with the reduced ilia in other taxa). It would be unsurprising if other madtsoiids also possessed hindlimbs as complete as those of Najash.

 Several madtsoiid genera have been named using indigenous words for legendary Rainbow Serpents or dragons, including Wonambi (Pitjantjatjara), Yurlunggur (Yolngu) and Nanowana (Ancient Greek nano-, 'dwarf' + Warlpiri Wana) in Australia, and Herensugea (Basque) in Europe. G.G. Simpson (1933) apparently started this trend by compounding Madtsoia from indigenous roots. In this particular case these originated from the Tehuelche language, although the reference made was geographic rather than mythological, the derivation being from that language's terms mad, "valley" and tsoi, "cow" as a rough translation from Spanish name of the type locality, Cañadón Vaca.

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 Eupodophis descouensi — древняя змея из семейства Pachyophiidae, у которой сохранились ноги.

 Окаменевшие останки обнаружены в Ливане близ деревушки Аль-Наммура в 2000 году. Возраст находки — около 92 миллионов лет.

 Eupodophis is an extinct genus of snake from the Late Cretaceous period. It has two small hind legs and is considered a transitional form between Cretaceous lizards and limbless snakes. The feature, described as vestigial, was most likely useless to Eupodophis. The type species Eupodophis descouensi was named in 2000. The specific name is dedicated to the French naturalist Didier Descouens.

 The fossilized specimen from which the description of the type species was based was 85 cm (33.5 in) long and is approximately 92 million years old. It was found in Cenomanian-age limestone near the al-Nammoura village in Lebanon.

 Eupodophis was a marine snake that lived in the Mediterranean Tethys Ocean. It had a laterally compressed body and short, paddle-like tail. The vertebrae and ribs of Eupodophis are pachyostotic, or thickened, as an adaptation to a marine lifestyle. The pelvic bones are small and weakly attached to each other. Tarsal bones are present but reduced in size and form. The metatarsals and phalanges of the foot are absent.

 The fossil skeleton of Eupodophis was analyzed using synchrotron x-rays at the European synchrotron radiation facility in Grenoble, France. The researchers determined that the hind limb on one skeleton was 0.8 inches long, with an "unmistakable" fibula, tibia and femur. One limb was visible on the surface of the fossil while the other was hidden within the limestone. The scans were compared with similar ones taken of the limbs of extant lizards including the Gila monster, Green Iguana, and several species of monitor lizard.

 While they are very small in comparison to limbed reptiles, the hind limbs of Eupodophis possess much of the same anatomy as modern lizards. This suggests that the bones of Eupodophis became reduced in size through a change in the rate of bone growth, not major anatomical changes. The lack of thickening at either end of the limb bones suggests that growth had stopped occurring in the limbs at one point in the animal's lifetime. While the vertebrae and ribs of Eupodophis are pachyostotic and osteosclerotic (meaning that the outer and inner parts of the bone are compact), the limb bones remain light. This lightness is also seen in the bones of terrestrial lizards, suggesting that the limbs had not been part of the overall adaptation of the skeleton for an aquatic lifestyle.

 The loss of limbs in Eupodophis may have been the result of changes in Hox genes, genes that specify the development specific regions of the body. Because Hox genes are involved in determining specific features of the axial skeleton, the loss of limbs would also result in the loss of cervical (tail) vertebrae that are near them. This loss is seen in Eupodophis and modern snakes but not legless lizards, which may be far less common because some other factor besides Hox genes were involved in the loss of their limbs. The loss of digits on the hind limbs may be explained by a low number of cells in the limb bud during embryonic development.

 The loss of forelimbs and reduction of hind limbs in Eupodophis was likely an adaptation for swimming. While living snakes usually employ undulatory movement for moving over land, sinuous movements are also an effective means of moving through water. Large, well-developed limbs increase drag on swimming animals, so the limbs of Eupodophis and other early snakes may have become vestigial to save energy and make movement more efficient.

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 Pachyrhachis is an extinct genus of snake with well developed hind legs known from fossils discovered Ein Yabrud, near Ramallah, in the central West Bank. It is a relatively small snake, about 1 m (3–4 ft) long. Pachyrhachis appears to have been an ancient marine snake; the fossils occur in a marine limestone deposit, and the thickened bone of the ribs and vertebrae would have functioned as ballast to decrease the buoyancy of the animal, allowing it to dive beneath the ancient Cretaceous seas that it once inhabited.

 Pachyrhachis is one of three genera of Cenomanian snakes with hindlimbs. Although many modern pythons and boas still retain remnants of legs, in the form of small spurs, the tiny legs of Pachyrhachis included a hip, knee, and ankle joint. Pachyrhachis was originally described by Haas (1979, 1980) who noted it had a puzzling melange of snake and lizard features; its status as an early snake was later confirmed (Caldwell and Lee 1997).

 The position of Pachyrhachis within snakes has been debated (e.g. Lee and Scanlon 2002; Rieppel et al. 2003). Pachyrhachis is among the oldest known snakes and retains well-developed hind limbs, suggesting it represented a transitional form linking snakes to marine lizards (Lee and Scanlon 2002), though other studies place Pachyrhachis within the modern snake radiation Macrostomata (Zaher & Rieppel, 1999).

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 Najash is an extinct basal snake from the Late Cretaceous Candeleros Formation of Patagonia. Like a number of other Cretaceous and living snakes it retained hindlimbs, but Najash is unusual in having well-developed legs that extend outside the rib cage, and a pelvis connected to the spine. Fossils of Najash were found in the terrestrial Candeleros Formation, in Rio Negro Province, Argentina, and date to roughly 90 million years ago. The skull and spine of Najash both show adaptations for a subterranean existence, consistent with the hypothesis that the long bodies and reduced limbs of snakes are an adaptation for burrowing.

 This burrowing creature had not lost its sacrum, the pelvic bone composed of several fused vertebrae, nor its pelvic girdle which are absent in modern snakes, and in all other known fossil snakes as well. Several phylogenetic analysis place Najash as either the most primitive known snake, or near the base of the snake radiation, but outside of all living snakes.

 This discovery does not support the hypothesis, first offered by the nineteenth-century paleontologist Edward Drinker Cope, that snakes share a common marine ancestry with mosasaurs. The marine origin hypothesis received new impetus with the discovery in the 1990s of basal snakes with vestigial limbs in marine sediments in Lebanon.

 The generic name comes from the biblical legged snake of Genesis, Nahash, who tempted Adam and Eve to eat from a forbidden fruit tree.

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 Pleurosaurus  is an extinct genus of diapsid reptile belonging to the order Sphenodontia, and therefore related to the modern tuatara. Pleurosaurus fossils were discovered in the Solnhofen limestone formation of Bavaria, Germany.

 Pleurosaurus is one of the few known aquatic sphenodontians. Its body was approximately 60 centimetres (2.0 ft) long, and elongated for hydrodynamic streamlining, with comparatively short limbs and a powerful tail. It would have been able to swim rapidly, by undulating its slender body in a snake-like fashion. It had only small limbs, which probably did not aid in swimming, and nostrils placed far back on the head, close to the eyes.

 Плеврозавры (Pleurosauridae) — семейство вымерших морских диапсидных рептилий из отряда клювоголовых (Sphenodontia). Останки этого семейства были найдены в Баварии в отложениях юрского и мелового периода.

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 Clevosaurus (CLEE-vo-SORE-us) ("Gloucester lizard") is an extinct genus of sphenodontian reptile from the Triassic and the Jurassic periods of Nova Scotia, Great Britain, (C. bairdi) and Yunnan (C. mcgilli). Clevosaurus was extremely similar to the modern tuatara in almost every way; the two genera differ in only certain features of the teeth and skull anatomies, as well as size. Clevosaurus was smaller than the modern Tuatara. Clevosaurus possibly ate plants as well as insects, as suggested by the form of the teeth. Fossils of Clevosaurus, as well as other sphenodontians, early mammals and dinosaurs have been found in ancient cave systems of Great Britain. Clevosaurus is now believed to have had Pangaean distribution.

 Some fossils from South America (into Geopark of Paleorrota) found in 2006 represent a new species of Clevosaurus (C. brasiliensis).

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 Brachyrhinodon is an extinct genus of sphenodontian from the Triassic of Scotland .

 Sphenodontia is an order of lizard-like reptiles that includes only one living genus, the tuatara (Sphenodon), and only two living species. Despite its current lack of diversity, the Sphenodontia at one time included a wide array of genera in several families, and represents a lineage stretching back to the Mesozoic Era.

 Sphenodonts, and their sister group Squamata (which includes lizards, snakes and amphisbaenians), belong to the superorder Lepidosauria, the only surviving taxon within Lepidosauromorpha. Squamates and sphenodonts both show caudal autotomy (loss of the tail-tip when threatened), and have transverse cloacal slits. The origin of the sphenodonts probably lies close to the split between the Lepidosauromorpha and the Archosauromorpha. Though they resemble lizards, the similarity is superficial, because the group has several characteristics unique among reptiles. The typical lizard shape is very common for the early amniotes; the oldest known fossil of a reptile, the Hylonomus, resembles a modern lizard.

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