Palaeopascichnus Palij 1976

Genus Palaeopascichnus Palij, 1976 TYPE SPECIES. — Palaeopascichnus delicatus Palij, 1976 by original designation. INCLUDED FOSSIL SPECIES. — P. delicatus Palij, 1976, P. gracilis Fedonkin, 1985 and P. linearis (Fedonkin, 1976). REMARKS The Ediacaran fossils belonging to the palaeopascichnid group and more particularly to Palaeopascichnus remain enigmatic. The description and diagnosis of Palaeopascichnus and related species were oriented by their morphological characteristics and possible affinity (for example trace fossils vs. body fossils). Kolesnikov & Desiatkin (2022) recalled that the initial definition of Palaeopascichnus was established for an ichnogenus, a concept subsequently abandoned (see discussion). Recent taxonomic studies (Kolesnikov et al. 2018a, b; Kolesnikov & Desiatkin 2022) proposed to include Orbisiana Sokolov, 1976 as well as P.gracilis Fedonkin, 1985 and P.linearis (Fedonkin, 1976) within the palaeopascichnids. They further excluded species differing significantly from classic palaeopascichnid fossils such as Palaeopascichnus minimus Shen, Xiao, Dong, Zhou & Liu, 2007, P. meniscatus Shen, Xiao, Dong, Zhou & Liu, 2007 (Shen et al. 2007), P. wangjiawamensis (Jigeng, Daqing & Tinggui, 2009), and P.jiumenensis (Dong, Xiao, Shen & Zhou, 2008). Consecutively a new approach to Palaeopascichnus was proposed by Kolesnikov et al. (2018a, b) and Kolesnikov & Desiatkin (2022) as follows: Recumbent colonial agglutinated chambered organisms. Chambers are globular or elongated; they are organized in series that branch repeatedly. Width and/or length of chambers can be consistent with each specimen, but in most cases it is gradually increasing at various rates.