The phylogenetic position of Nyctiphruretus acudens, a parareptile from the Permian of Russia

Abstract

Several specimens preserving the cranial structure of Nyctiphruretus acudens, a parareptile from the Permian Mezen River locality, Russia, are described here for the first time. Previous studies have offered conflicting reconstructed images of Nyctiphruretus but no illustrations of actual specimens. The new information was incorporated into two existing analyses of parareptilian relationships. The results indicate that Nyctiphruretus is closely related to procolophonoids, pareiasaurs and other non-pareiasaurian Mezen River parareptiles but the interrelationships within this group remain unresolved. Nyctiphruretus was recovered either as the sister taxon of a clade formed of pareiasaurs and the other non-pareiasaurian Mezen River parareptiles, or as the sister taxon of procolophonoids. This is the first time the Nyctiphruretus-Procolophonoidea clade received support in a phylogenetic analysis. The interrelationships between several other groups within the Parareptilia also remain unresolved, or poorly supported, highlighting the need for more detailed descriptions and analyses of this enigmatic group of extinct reptiles.Keywords: Parareptilia, Procolophonoidea, Nyctiphruretus acudens, phylogeny, Permian, Russia. ResumenSe describen por primera vez varios ejemplares de Nyctiphruretus acudens que han conservado su estructura craneal, un parareptil del Pérmico de la localidad de Mezen River en Rusia. En estudios previos se documentaron imágenes conflictivas de Nyctiphruretus aunque nunca se publicaron ilustraciones del material fósil. La nueva información se ha incorporado a dos análisis ya publicados de las relaciones de parentesco de parareptiles. Los resultados indican que de Nyctiphruretus está próximamente emparentado con procolofónidos, pareiasaurios y otros parareptiles no-pareiasaurios de Mezen River, aunque las interrelaciones dentro de este grupo quedan sin resolver. Nyctiphruretus aparece como el grupo hermano de un clado formado por pareiasaurios y los demás parareptiles ISSN (print): 1698-6180. ISSN (online): 1886-7995

First procolophonid (Reptilia, Parareptilia) from the Lower Triassic of Madagascar

“…Morphological variation occurring in the latter (MacDougall and Modesto, 2011;MacDougall et al, in press;Modesto and Damiani, 2007) still indicates that this condition should be regarded as a variant of the broadly excavated emargination seen in most procolophonids (Cisneros, 2008a). It is distinct from the acute emargination formed by the boomeranglike jugal in Nyctiphruretus (Säilä, 2010b) and Owenettidae (Meckert, 1995;Reisz and Scott, 2002). In the postorbital region, the supratemporal is partly preserved.…”

“…The new Malagasy procolophonid was added to the data matrix in order to test its phylogenetic position. In a recent redescription, N. acudens was shown having an acute temporal emargination (Säilä, 2010b). This taxon was therefore rescored accordingly as '1' for character 13.…”

The postcranial skeleton of the Early Triassic parareptile Sauropareion anoplus, with a discussion of possible life history

“…Following Cisneros (2008b), Nyctiphruretus acu− dens served as the outgroup. However, whereas Cisneros (2008b) originally coded N. acudens as having a squamosal that terminated at least as far ventrally as the quadratojugal, newer studies reveal that the squamosal does not extend as far ventrally as the quadratojugal at the tympanic notch (Säilä 2010b;Laura K. Säilä personal communication, 2011). Thus, the polarity of character 14 was reversed.…”

Amniote faunal revision of the Pictou Group (Permo-Carboniferous), Prince Edward Island, Canada

“…There are 29 tooth positions, exceeding the number known in any other parareptile, with the possible exception of lanthanosuchoids and Nyctiphruretus (Chudinov, 1957;Efremov, 1946;Säilä, 2010). The most mesially positioned teeth taper gently towards their apex, and exhibit a distally directed curve that terminates in a pointed tip (Fig.…”