Nyctiphruretus acudens Efremov, 1938

Säilä, Laura K., 2009, Alpha taxonomy of the Russian Permian procolophonoid reptiles, Acta Palaeontologica Polonica 54 (4), pp. 599-608 : 605

Nyctiphruretus acudens Efremov, 1938 Nyctiphruretus optabilis Bulanov, 2002

This genus of parareptile found in Mezen’ River basin of Russia, Upper Middle Permian (Guadalupian) ( Ivakhnenko 1990), has been considered a member of the order Procolophonomorpha , family Nyctiphruretidae , and understood to be the most basal of the Russian “procolophons” ( Ivakhnenko 1979, 1987, 1997; Tverdockhlebova and Ivakhnenko 1994; Bulanov 2002). The recent phylogenetic analyses of Lee (1995), Tsuji (2006), and Müller and Tsuji (2007), however, do not support the view of Nyctiphruretus as a basal “procolophon” and instead recognise Nyctiphruretus as a non−procolophonoid parareptile, possibly more closely related to pareiasaurs than procolophonoids ( Tsuji 2006). However, Tsuji (2006) points out that the published reconstructions of Nyctiphruretus ( Efremov 1940; Chudinov 1957; Ivakhnenko 1979; Lee 1995, 1997) differ from each other markedly, and an in−depth study of this taxon is needed to resolve its real phylogenetic position. There are currently over one hundred specimens of Nyctiphruretus acudens , including cranial and postcranial remains, housed at PIN, whereas Nyctiphruretus optabilis is known from only one fragmentary dentary ( Bulanov 2002). A detailed ontogenetic study of Nyctiphruretus is forthcoming by Valery Bulanov, and a study of the cranial osteology and phylogenetic position of Nyctiphruretus is being prepared by the author. Preliminary results of the osteological and phylogenetic study, however, indicate that while Nyctiphruretus appears to share several more characters with procolophonoids than has been recognized in previous studies and might be a close relative of procolophonoids, it does not fall within the superfamily Procolophonoidea .