Ohaniella gen. nov., a new whole-plant bennettite from the Oxfordian (Upper Jurassic) Tochikubo Formation of Shidazawa, Fukushima, northeast Japan

Abstract

The discovery of excellently preserved articulated plant fossils from the Oxfordian (Upper Jurassic) Tochikubo Formation of Shidazawa, Minamisoma, Fukushima, northeast Japan, allows for the description and reconstruction of the new fossil whole-plant bennettitalean Ohaniella ptilofolia gen. et sp. nov., based on preserved axes with attached foliage of the Ptilophyllum jurassicum-type and attached ovuliferous reproductive structures (flowers/seed cones). Recent excavations unveiled plant fossils with axes carrying a whorl of apically arranged leaves, in the centre of which remnants of ovuliferous reproductive structures in the form of possible seed cones are preserved. The findings of Weltrichia-like microsporangiate flowers in the same bedding planes on slabs exclusively yielding foliage of the Ptilophyllum jurassicum-type suggest that (a) these might have been produced by the plants carrying Ptilophyllum jurassicum-type foliage and just have been shed as was the case in the closely related Kimuriella densifolia, and (b) Ohaniella ptilofolia gen. et sp. nov. plants might have formed more or less monotypic stands of shrub thickets referring to special environmental conditions and requirements.