Occurrence of Brachyoxylon wood from the Upper Jurassic of Beijing, northern China

Abstract

ABSTRACT The fossil wood genus Brachyoxylon Hollick et Jeffrey, as an important component of Mesozoic palaeoxylogical assemblages, was widely recorded throughout the world. However, Brachyoxylon fossils were rarely documented in China, and were all reported from the Lower Cretaceous. The Upper Jurassic Tuchengzi Formation is one of the most significant horizons for Jurassic petrified wood in northern China. A new fossil wood species, Brachyoxylon yanqingense sp. nov., was described from the Tuchengzi Formation in Yanqing District of Beijing City, northern China. Anatomically, the new species is characterised by having mixed tracheary radial pitting and araucarioid cross-field pitting. The new finding provides a fresh Jurassic record of Brachyoxylon in China and contributes to further understanding the tempo-spatial distribution of Brachyoxylon in Far-East Asia during the Late Mesozoic. As a fossil wood genus, Brachyoxylon has commonly been related to the extinct conifer family Hirmeriellaceae (Cheirolepidiaceae). Together with an analysis on the floral composition of the Tuchengzi Formation, it is proposed that the Hirmeriellaceae was one of the dominant groups of the forest vegetations in this Late Jurassic flora.