New species of the genus Schizolepidopsis (conifers) from the Albian of the Russian high Arctic and geological history of the genus

Abstract

A plant fossil assemblage recently recovered from two localities belonging to the Albian Balyktakh Formation in the lower reaches of the Tuor-Yuryakh River in Kotelnyi Island (New Siberian Islands) is studied in detail. A new conifer (family Pinaceae) species Schizolepidopsis borealis Domogatskaya et Herman, sp. nov. is described. The species possesses large loose racemose polysperms (seed cones) with deeply dissected bilobate seed scales. A close association of these female cones with two species of conifer leaves, Pityophyllum ex gr. nordenskioeldii and P. ex gr. staratchinii, is reported. These three species representing reproductive and vegetative (foliar) organs probably belonged to the same whole plant species when living. Taxonomy and nomenclature of the genus Schizolepidopsis are considered and 20 new combinations are proposed and validated for previously described Schizolepis species. The palaeobotanical data for reconstructing the distribution of the genus Schizolepidopsis in space and time are based on the analysis of literature resources for 79 species covering the Late Permian to Early Cretaceous. The genus was first recorded, with some uncertainty, in the Late Permian. During the Jurassic and Early Cretaceous there was an increase in the number of Schizolepidopsis species and simultaneously the centre of the genus diversity gradually moved eastwards and north-eastwards, probably due to climate warming. It is likely that Schizolepidopsis plants became extinct close to the Albian-Cenomanian boundary due to competitive replacement by more advanced pinaceous conifers possessing compact cones with densely arranged seed scales that ensured better ovule protection.