First data on coniferous leaves from the Middle Jurassic of the Belgorod Region, Russia

Abstract

Data on fossil coniferous leaves from the Middle Jurassic of the Stoilensky open mine in the Belgorod Region, Russia were obtained for the first time. These conifers are represented by the leaves of Mirovia, Podocarpophyllum, Elatocladus and Pityophyllum. A new species, Mirovia oskolica, sp. nov., is described based on the study of the morphology and epidermal features. Leaves of this species are characterized by the presence of thick resin ducts, stomata arranged in one stomatal zone, the short epidermal cells of the adaxial leaf side, the absence of papillae on the ordinary epidermal cells, and the rare presence of small proximal papillae on some subsidiary cells of the stomata. In addition, we have found leaves similar to the type leaves of M. eximia from the Middle Jurassic of the Kursk Region, Russia. We determine linear leaf fragments with longitudinally orientated stomata arranged in two stomatal bands and with narrow guard cells as Podocarpophyllum kazachstanicum, originally described from the Lower Jurassic of Kazakhstan. Besides these remains, there are numerous fragments of the narrower linear leaves with an acute apex, two stomatal bands and a very thin cuticle. These leaves are assigned to Pityophyllum sp. The only found sessile lanceolate leaf and several dispersed cuticle fragments with obliquely to transversely oriented stomata in the stomatal bands are determined as Elatocladus sp.