Permineralized taxodiaceous seed cones from the upper cretaceous of Hokkaido, Japan

Abstract

A new taxodiaceous fossil genus, Mikasastrobus hokkaidoensis gen. et sp. nov. is described on the basis of six permineralized seed cones and a leafy shoot collected from the Upper Cretaceous (Coniacian-Santonian) of Hokkaido, Japan. The peel technique was applied for the anatomical observations. The fossil cone is terminal on a leafy shoot, ovoid in shape. 3–4 cm long and up to 2–3.5 cm in diameter, consisting of an axis and numerous cone scale complexes arranged helically around the axis. The complex is flattened and consists of an expanded apical half and stalk-like basal half. Each complex subtends a small-sized ovuliferous scale with 4–5 inverted ovules on its adaxial side. The serial sections show that each complex receives a single strand from the axis which later divides into many strands. Despite the presence of an ovuliferous scale tip, like that of Cunninghamia, the present fossil cone are most similar to Taiwania in their arrangement of strands.