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Exceptionally well-preserved impression fossils of Cyrillopteris (ex. Odontopteris) orbicularis (Halle) comb. et emend. nov. have been described from the lower part of the middle–upper Permian Upper Shihezi (Upper Shihhotse) Formation in Yangquan City, Shanxi Province, North China. For the first time, this typical Cathaysian seed fern is confirmed to have a bipartite frond with two bipinnate branches, comparable with that of C. genuina (Grand’Eury) Laveine et Oudoire from the Pennsylvanian of France. Entire-margined cyclopteriod elements occur in the proximal portion of the long petiole. With increasing proximity of the bifurcation, the cyclopteroid elements progressively differentiate into pinnae with individual pinnules. True intercalary pinnules, which would be fully inserted on the primary rachides, are not present. Characteristics of our new specimens provide new information on the frond architecture of C. orbicularis (Halle) comb. et emend. nov., and allow a relatively complete circumscription of the overall features of this taxon, an emendation of the species diagnosis, and the presentation of an accurate frond reconstruction. Specimens of C. orbicularis comb. et emend. nov. are preserved with mesophytes and xerophytes from the same interval, demonstrating the vegetation in the research area grew under a seasonal subhumid to semiarid climates during the late Guadalupian.more » « less
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A silicified trunk,Zhuotingoxylon liaoiWan, Yang, Wang, Liu et Wang gen. 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 thick‐walled 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.more » « less
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