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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Tags: Вымершие рептилии, Мел, диапсиды, змеи, лепидозавроморфы, лепидозавры, мадтсоииды, чешуйчатые

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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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Tags: Вымершие рептилии, Мел, диапсиды, змеи, лепидозавроморфы, лепидозавры, мадтсоииды, чешуйчатые

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