Zhuotingoxylon liaoi gen. et sp. nov., a silicified coniferous trunk from the Changhsingian (Permian) of southern Bogda Mountains, northwestern China

Abstract

et sp. nov., is described from the uppermost part of Guodikeng Formation in South Taodonggou section, Turpan-Hami Basin, Xinjiang Uygur Autonomous Region, northwestern China. It is characterized by a solid pith, endarch primary xylem and pycnoxylic wood. The pith is composed of parenchyma and sclereids. Radial walls of primary xylem tracheids have spiral and scalariform thickenings. Secondary xylem consists of thickwalled tracheids and parenchymatous rays. Uniseriate rounded pits with oval apertures are distributed on radial tracheidal walls separately. Cell walls of rays are homogeneous and smooth. Rays are 1-10 cells high in tangential section. Cross-field pits are cupressoid. There are 1-4 bordered pits with slit-like to oval apertures in each cross-field. Based on the anatomical features of the pith and xylems, it is proposed that the new stem has a coniferous affinity. The new fossil stem adds to the knowledge of vascular plant diversity close to the Permian-Triassic boundary.

The Taphonomic Character, Occurrence, and Persistence of Upper Permian–lower Triassic Plant Assemblages in the Mid-Paleolatitudes, Bogda Mountains, Western China

“…In situ , silicified trunks with attached rooting in paleosols are uncommon. The systematics of many of these wood assemblages have been published by Wan et al (2014, 2017, 2021a). In addition to permineralized roots attached to upright trunks, one stratigraphic interval in South Taodonggou preserves both in situ , vertically oriented and non-oriented, permineralized rooting structures in sandy coarse siltstone (Wan et al 2019a).…”

“…At least one trunk exhibits interior rot prior to silicification and compaction, resulting in the distortion of the basal part of this particular tree upon compaction of entombing sediment. The wood consists of tracheids with araucarian-type pitting and rays with one to two large, simple pits in each cross-field; this wood is assigned to Zhuotingoxylon (Wan et al 2021a). Rooting structures are not permineralized, but are coalified and compressed (Fig.…”

“…9C). Permineralized transported logs have been reported from the lower (Wan et al 2014) and upper (Wan et al 2021a) Wutonggou, Jiucaiyuan (Wan et al 2019b), and the Shaofanggou LCs. Their frequency of occurrence is very low relative to available stratigraphic thickness (see below).…”