Juniperus L. (Cupressaceae) from the Miocene of Chifeng, Inner Mongolia: the earliest macrofossil of sect. Sabina in East Asia

Abstract

ABSTRACT Juniperus L. is the second largest conifer genus, having the widest distribution of all conifer genera. However, its evolution in East Asia is unclear due to the scarce fossil records. We described a set of Juniperus fossils from the Early Miocene of Tiejianggou, Chifeng, Inner Mongolia. Although only two seed cones and five branch segments were preserved, the fossils were assigned to Juniperus chifengensis Liang Xiao et Liyan Guo sp. nov. (Cupressaceae). The diagnostic characteristics include leaves in a decussate or ternate arrangement, both scalelike and needle-like leaves on mature branchlets, scalelike leaves on juvenile branchlets, leaves with two stomatal bands adaxially and abaxially, terminal seed cones, and two or four seeds, which is the most similar extant species J. chinensis morphologically. However, the cuticle of the abaxial epidermis shows longer and more disordered cells. With a close affinity to the extant Juniperus chinensis, J. chifengensis, the macrofossil record of sect. Sabina (Juniperus) in East Asia, had existed in East Asia in the early Early Miocene. The longer abaxial epidermal cells confirm its adaptation to the dry and cold climate that occurred from the Early Miocene to the present.