Najash rionegrina Apesteguia & Zaher 2006
Creators: name: Zaher, Hussam
name: Apesteguía, Sebastián
name: Scanferla, Carlos Agustín
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Squamata
Madtsoiidae
Najash
Najash rionegrina

description: NAJASH RIONEGRINA APESTEGUÍA & ZAHER, 2006   
 Diagnosis: As for the genus, of which this is the only known species.   
 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).   
 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).   
 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).   
 Locus typicus: La Buitrera, Rentería Mesa, 30 km north-west from the town of Cerro Policia.
description: Published as part of 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, pp. 801-826 in Zoological Journal of the Linnean Society 156 on pages 803-804