A new and diverse plant fossil assemblage from the upper Westphalian Benxi Formation, Shanxi, China, and its palaeofloristic significance

Abstract

A diverse assemblage of Carboniferous plant fossils occurs in the upper Benxi Formation at the Kaihuagou Section near Taiyuan, Shanxi, China. It consists of impressions and fusain fragments, the latter revealing anatomical details. Unlike previously published assemblages from the Benxi Formation, there are no pteridosperms, but a predominance of noeggerathioids and fern fragments. There are three new species: Achlamydocarpon taiyuanensis, Conchophyllum suboblongifolium, and the first reported example of a Selaginella from the Carboniferous System of China, S. benxiensis. The arborescent lycophytes do not to belong to Lepidodendron, as previously claimed, but to Synchysidendron, and three new combinations are therefore proposed for species from the Benxi Formation: S. galeatum, S. subrhombicum and S. tripunctatum. The Benxi Formation flora represents a transition between the tropical swamp vegetation represented in the Westphalian floras of Europe and North America, and the Stephanian and Permian Cathaysian floras of China. It is evidence of an essential continuity between the Late Palaeozoic vegetation of the western and eastern tropics, which should be united as a single phytochorion, the Amerosinian Realm.