identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
039F87A4A57DFFFC2342FB6FFB978FA5.text	039F87A4A57DFFFC2342FB6FFB978FA5.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Najash APESTEGUIA AND ZAHER 2006	<div><p>NAJASH APESTEGUÍA AND ZAHER, 2006</p> <p>Emended diagnosis: A snake nearly 2 m long with robust hindlimbs and a sacrum, tip of dentaries with a medially projected facet that bears a straight anteroposteriorly directed margin, suggesting a tightly connected mandibular symphysis, lack of dentary shelf, prootic exposed dorsally between the otooccipital and parietal, lack of laterosphenoid, developed laterally projected basipterygoid process, lack of a crista circumfenestralis, robust stapedial footplate, single large parazygantral foramen on vertebrae, arqual ridges on middle and posterior presacral vertebrae, and blunt haemapohyses on caudal vertebrae. It exhibits the following autapomorphies: (1) a thick splenial; (2) strongly concave ventral surface of the parasphenoid rostrum, forming a deep and straight gutter; (3) strongly faceted condition of the neural arch laminae; (4) enlarged and blade-like femoral trochanter.</p></div> 	https://treatment.plazi.org/id/039F87A4A57DFFFC2342FB6FFB978FA5	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Zaher, Hussam;Apesteguía, Sebastián;Scanferla, Carlos Agustín	Zaher, Hussam, Apesteguía, Sebastián, Scanferla, Carlos Agustín (2009): The anatomy of the upper cretaceous snake Najash rionegrina Apesteguía & Zaher, 2006, and the evolution of limblessness in snakes. Zoological Journal of the Linnean Society 156: 801-826
039F87A4A57DFFFD230FF8FFFABE881A.text	039F87A4A57DFFFD230FF8FFFABE881A.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Najash rionegrina Apesteguia & Zaher 2006	<div><p>NAJASH RIONEGRINA APESTEGUÍA &amp; ZAHER, 2006</p> <p>Diagnosis: As for the genus, of which this is the only known species.</p> <p>Holotype: Museo Provincial Carlos Ameghino, Cipolletti, Río Negro, Argentina (MPCA) 389–400. The holotype consists of a series of associated materials, including a large fragment of the left dentary and anterior portion of the corresponding splenial (MPCA 390), and a nearly complete and articulated postcranial skeleton, composed of 16 sections bearing a total of at least 122 articulated vertebrae (109 presacrals, two sacrals, and 11 caudals), a pelvic girdle, and hindlimbs. The holotype is represented by the following articulated and associated postcranial elements: an articulated section bearing the axis, four anterior presacral vertebrae, and the broken anterior part of the fifth vertebra (MPCA 391); a section bearing a continuous string of 47 articulated presacral vertebrae, with associated ribs and two isolated vertebrae (MPCA 392), from which the proximal head of a middle presacral rib (MPCA 389) was prepared separately; three sections bearing no more than six, seven, and nine presacral vertebrae, respectively (MPCA 393); two sections bearing only associated ribs (MPCA 394); one section bearing five articulated midpresacral vertebrae, and the broken anterior part of a sixth vertebra (MPCA 395); two articulated caudal vertebrae (MPCA 396); eight fragmentary sections bearing a total of 18 articulated presacral vertebrae (MPCA 397); five undetermined and fragmentary elements (MPCA 398); several fragmentary associated presacral vertebrae (MPCA 399); a section containing the pelvic girdle and hindlimb elements, articulated with eight posterior presacral, two sacral, and nine caudal vertebrae (MPCA 400).</p> <p>Referred material: Five specimens: (1) a fragmentary skull comprising the posterior half of the braincase, and associated vertebrae of a small specimen (MPCA 385); (2) several associated cranial and vertebral elements of a larger individual, probably twice as large as the holotype, including an incomplete left dentary (MPCA 380), two undetermined cranial elements (possibly mandibular fragments) (MPCA 381 and 382), axis (MPCA 383), and associated presacral and caudal vertebrae (MPCA 384); (3) a right quadrate and five associated presacral vertebrae (MPCA 387); (4) four associated sections of articulated vertebrae, and one fragment totaling 16 middle presacral vertebrae (MPCA 386); (5) a posterior presacral vertebra of a large individual (MPCA 388).</p> <p>Stratum typicum: Mid to upper layers of the Candeleros Formation, basal unit of the Neuquén Group, early Upper Cretaceous. The bearing strata, about 40 m under the boundary with the overlying Huincul Formation, are considered as having been deposited around 92–94 Mya, during the Cenomanian. The fission track study on a tuff in the overlying Huincul Formation gave an age of 88 ± 3.9 Myr (Corbella et al., 2004).</p> <p>Locus typicus: La Buitrera, Rentería Mesa, 30 km north-west from the town of Cerro Policia.</p></div> 	https://treatment.plazi.org/id/039F87A4A57DFFFD230FF8FFFABE881A	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Zaher, Hussam;Apesteguía, Sebastián;Scanferla, Carlos Agustín	Zaher, Hussam, Apesteguía, Sebastián, Scanferla, Carlos Agustín (2009): The anatomy of the upper cretaceous snake Najash rionegrina Apesteguía & Zaher, 2006, and the evolution of limblessness in snakes. Zoological Journal of the Linnean Society 156: 801-826
039F87A4A56CFFE8237DFC51FD798D58.text	039F87A4A56CFFE8237DFC51FD798D58.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Najash : A FRESH START FOR THE DEBATE ON THE	<div><p>NAJASH: A FRESH START FOR THE DEBATE ON THE</p> <p>EVOLUTION OF LIMBLESSNESS IN SNAKES</p> <p>Forelimbs are completely absent in all extant snakes, and in the fossil snakes Pachyrhachis, Haasiophis, Eupodophis, Dinilysia, and Najash. On the other hand, hindlimbs persist in several families of extant snakes as rudimentary elements, consisting of a pelvic girdle, a rudimentary femur, and an external claw-like vestige. These elements are completely lost in the derived Caenophidian snakes, and in a number of unrelated alethinophidian snake families (i.e. Xenopeltidae, most Uropeltinae, the genus Tropidophis within Tropidophiidae, Bolyeriidae, and Xenophidiidae).</p> <p>The presence of fully formed hindlimbs in the Tethyan marine limbed snakes Haasiophis, Pachyrhachis, and Eupodophis enforced the idea that they were the most primitive snakes known, and that they were perfect transitional taxa linking extant snakes to the marine mosasauroids (Caldwell &amp; Lee, 1997). However, as previously suggested by Zaher &amp; Rieppel (2000), the appendicular skeleton of the Cenomanian marine limbed snakes corresponds more accurately to a derived ophidian morphology, with free lymphapophyses and a pelvis that is not suspended from the axial skeleton, but rather lies within the ribcage and lacks a differentiated sacral region (Fig. 13). On the other hand, Najash lacks free lymphapophyses, and retains two sacral vertebrae that anatomically separate the trunk region from the caudal region, with a pelvis that is functionally but loosely connected to the sacral region, and which lies outside of the ribcage: all being plesiomorphic nonophidian conditions (Fig. 13).</p> <p>The loss of a sacral region and consequent disconnection of the pelvis from the axial skeleton represents a synapomorphy of extant snakes, shared by Pachyrhachis, Haasiophis, and Eupodophis, whereas the presence of free lymphapophyses is a derived feature shared by extant snakes, Pachyrhachis, and probably Haasiophis, but not by Eupodophis (Rage &amp; Escuillié, 2000; Rieppel &amp; Head, 2004). The re-interpretation of the postcranial anatomy of Pachyrhachis, Haasiophis, and Eupodophis renders it more closely comparable with the rudimentary hindlimbs of extant snakes than to non-ophidian squamates, a result that is in accordance with a derived position of these fossil taxa within the extant snake clade (Zaher, 1998; Tchernov et al., 2000; Rieppel et al., 2002; Apesteguía &amp; Zaher, 2006), rather than as the basalmost snakes (Caldwell &amp; Lee, 1997; Rage &amp; Escuillié, 2000).</p> <p>Scanlon &amp; Lee (2000) and Rage &amp; Escuillié (2000) reported the presence of true chevron bones (Y-shaped elements that articulate or fuse with paired pedicels located at the posterior margin of the centrum of the caudal vertebrae) in W. naracoortensis and E. descouensi, respectively, another allegedly primitive feature of these snakes. However, Rieppel &amp; Head (2004) argued convincingly that the structures called ‘chevron bones’ in Eupodophis are unique, and not homologuous with the chevron bones of other squamates. The two arms of the Y-shaped element embrace an unpaired, blade-like pedicel that is located at the anterior end of the centrum, a morphology that is not comparable with any condition known in non-ophidian squamates (Rieppel &amp; Head, 2004: 21). Similarly, the assignment of a single disarticulated caudal vertebra with a chevron bone to W. naracoortensis by Scanlon &amp; Lee (2000) was questioned by Rieppel et al. (2002), as this vertebra might not belong to the specimen described by Barrie (1990; but see Scanlon, 2005: 143).</p> <p>Scanlon (1993) recognized the presence of true haemapophyses (paired pedicels, laminae, or rod-like projections that do not fuse with each other distally, located at the posterior margin of the centrum of the caudal vertebrae) in the caudal vertebrae of an undetermined species of Patagoniophis from the Eocene of Tingamarra (Queensland), and Rage (1998) described haemapophyses in the posterior caudal vertebrae of Madtsoia camposi Rage, 1998 from the Paleocene of Itaboraí (Brazil). The presence of true haemapophyses in Patagoniophis and Madtsoia suggest that most ‘Madtsoiids’ did retain the derived condition known for all snakes, and that the chevron bone reported in Wonambi by Scanlon &amp; Lee (2000) should be viewed with caution.</p> <p>It can be concluded that there is no unquestionable record of true chevron bones in snakes, and the presence of well-preserved haemapophyses in the posterior caudal vertebrae of N. rionegrina seems to support the view that chevron bones are absent in snakes (Fig. 12).</p> <p>The recent report by Cohn &amp; Tickle (1999) on Hox gene expression patterns in Python represents an important piece of evidence from a distinct source, which helps in the better understanding of the evolution of limblessness in snakes. However, some of their conclusions regarding the steps that led to the acquisition of limblessness in snakes need to be re-evaluated, according to the new morphological and phylogenetic implications brought by the subsequent discovery of N. rionegrina.</p> <p>Cohn &amp; Tickle (1999) suggested that the progressive expansion of Hox gene expression domains along the body axis is the main factor responsible for the evolution of limblessness in snakes, and would account for the loss of forelimbs, hindlimbs, and regional identity along the axial skeleton in snakes (i.e. distinct cervical, thoracic, lumbar, and sacral regions). These authors used Caldwell &amp; Lee’s (1997) phylogenetic hypothesis, in which Pr. problematicus represents the most primitive snake, and an intermediate form between mosasaurs and extant snakes, as a backbone hypothesis for their developmental scenario of snake evolution (Cohn &amp; Tickle, 1999: fig. 5). According to Cohn &amp; Tickle’s (1999) model, the expansion of Hox domains that led to the transformation of the entire axial skeleton towards thoracic identity, and to the reduction of hindlimb development by the elimination of the ectodermal competence, to form an apical ridge expansion, appeared only in the ancestor of extant snakes, excluding Pachyrhachis and, by extension, the remaining Tethyan marine legged snakes, Haasiophis and Eupodophis. Alternatively, if Najash represents the sister taxon to all known extant and extinct snakes, including Pachyrhachis, Haasiophis, and Eupodophis, and if the latter three are deeply nested within alethinophidian snakes as derived macrostomatans, then, according to the model advanced by Cohn and Tickle, the reduction of regional differentiation in the axial skeleton must have occurred in the ancestor of the clade formed by Najash and all other snakes, with the former retaining a sacral region posterior to a uniform presacral region (i.e. there was a loss of a distinct cervical region; phase 1 of Cohn and Tickle; Fig. 14). The loss of the sacral region through the transformation of the entire axial skeleton towards thoracic identity (phase 2 of Cohn and Tickle) appeared only posteriorly, in the ancestor of the clade formed by extant snakes, including the Tethyan marine legged snakes (Fig. 14). The loss of the sacral region also caused the disconnection of the pelvis from the axial skeleton and the consequent anteroventral dislocation of the entire appendicular skeleton to a position internal to the ribcage. The loss of the apical ridge might also have occurred concomitantly in phase 2 described above (Fig. 14). However, the potential of the hindlimb bud mesenchyme to act as a polarizing region, and to coordinate limb bud outgrowth, as shown by Cohn &amp; Tickle (1999) in Python, is retained not only in the latter genus, but also in most scolecophidians, anilioids, and macrostomatans. Such potential plasticity explains the strikingly distinct rudimentary patterns of the appendicular skeleton shown by scolecophidians, anilioids, and macrostomatans (Duerden &amp; Essex, 1923; Bellairs, 1950; List, 1955, 1966; Mlynarski &amp; Madej, 1961; Underwood, 1977). It also helps understand the presence of well-developed hindlimbs in the macrostomatan fossil snakes Pachyrhachis, Haasiophis, and Eupodophis.</p> <p>A possible explanation for the presence of hindlimbs in the Tethyan marine snakes is that the reduction of hindlimb elements occurred independently in the major basal clades of extant snakes (i.e. in Scolecophidia, Anilioidea, and Macrostomata) (Zaher &amp; Rieppel, 1999a; Greene &amp; Cundall, 2000). Under such a scenario (our preferred hypothesis), basal representatives of most major modern snake lineages would have retained somewhat well-developed hindlimb morphologies during the Cretaceous. The process of independent reductions to vestigial posterior hindlimbs during the late Cretaceous, and possibly early Cenozoic, also resulted in independent losses within these lineages (e.g. in Xenopeltidae, most Uropeltinae, the genus Tropidophis within Tropidophiidae, Bolyeriidae, Xenophidiidae, and Caenophidia). The hypothesis of independent losses is directly open to testing by the fossil record, as it presupposes that basal fossil representatives of all major extinct and extant lineages of modern snakes are likely to have retained well-developed hindlimb morphologies during at least the Cretaceous period (Zaher &amp; Rieppel, 1999a). Although the latter hypothesis is less parsimonious than the alternative re-development of complete hindlimbs in the Tethyan marine snakes, it fits more accurately with the new evolutionary scenario revealed by the intermediate morphology of Najash, which suggests that the loss of the sacral region occurred prior to the reduction of hindlimbs.</p> </div>	https://treatment.plazi.org/id/039F87A4A56CFFE8237DFC51FD798D58	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Zaher, Hussam;Apesteguía, Sebastián;Scanferla, Carlos Agustín	Zaher, Hussam, Apesteguía, Sebastián, Scanferla, Carlos Agustín (2009): The anatomy of the upper cretaceous snake Najash rionegrina Apesteguía & Zaher, 2006, and the evolution of limblessness in snakes. Zoological Journal of the Linnean Society 156: 801-826
