Sprecher
Beschreibung
Fossil plants from the interval of the uppermost Permian and lowerest Triassic succession of western China provide a means by which to assess the impact of the end-Permian mass extinction in the mid-latitudes of NE Pangaea. Here we describe a petrified forest from the uppermost part of the Wutonggou Formation in Xinjiang Autonomous Region, northwest China. The age of the fossil interval is the latest Permian (251.06 ~ 251.93 Ma), which are constrained by a number of geochronometric ages (ID-TIMS). Both allochthonous and autochthonous trunks with roots penetrating downward to the underlying palaeosols, are excavated. They are preserved in lacustrine deltaic deposits, and are explained to be a lakeshore foest that was buried by lake transgression. Anatomical analysis shows that the canopy of the forest is composed of at least four types of gymnosperms (Agathoxylon sp., Septomedullopitys sp., Protophylloocladoxylon sp., Zhuotingoxylon liaoii) and one type of calamitalean (Arthropitys sp.). Both marcro-fossil and palynological evidence testified that it was a gymnosperm-dominated forest. Fungal-plant, arthropod-plant, plant-plant interations have been observed from the petrified trunks, demonstrating a complex vegetational ecosystem around the lake. During the time when the forest alive, the end-Permian mass extinction event wiped out ~90% of marine species which were constrained to a short interval of ~60 kyr. Our finding of the latest Permian forests provides a rare window into how the largest biotic crisis in Earth’s history unfolded on land.
Key words: Changhsingian; fossil trunks; nurse logs; fungal hyphae; coprolites; palaeoecology