New records of Jurassic-Cretaceous boundary Tuchengzi Formation petrified wood from Yanqing, Bejing, China: palaeoclimatic implications.

Xenoxylon is an important boreal Mesozoic fossil wood genus and has been widely reported from sites across northern China. This paper reports well-preserved Xenoxylon wood from the Jurassic-Cretaceous boundary Tuchengzi Formation at Yanqing, Beijing, China. The fossil wood described here is ascribed to two species, i.e. Xenoxylon latiporosum and X. peidense. The present new finding enrichs our knowledge of the floral characteristics, especially the forest composition of the Tuchengzi Formation. These new records enlarge the fossil wood diversity of the genus Xenoxylon of the Tuchengzi Formation up to three species at Yanqing. Statistic results of the annual and mean sensitivity values of the X. latiporosum and X. peidense indicates that the trees inhabited under a sensitive climate with relatively stable interannual water supply. Additionally, some fungal remains represented by fungal hyphae were found with wood tissues of specimens of X. peidense. Typical wood rotting structures resembling those of the extant white rot are also found in X. latiporosum. This is the first record of fungal hyphae in Yanqing, Beijing, China, and provides us with new evidence that can be used to explore interactions between fungi and plants in the Late Jurassic. Institutional abbreviations: YQ = Yanqing Silicified Wood National Geopark, Beijing, China [ABSTRACT FROM AUTHOR]