New Discovery of Nanpiaophyllum fossils from the Heishanyao Formation in Qinhuangdao, Hebei Province

The Heishanyao Formation in the Liujiang Basin of the North China Platform is a lacustrine sedimentary sequence, but its geological age remains controversial, with two prevailing interpretations:Late Triassic or Early Jurassic. In this study, several unusual plant fossils were collected from Heishanyao Village and its surrounding areas in Shimenzhai Town, Qinhuangdao City, Hebei Province. Their morphology is largely consistent with that of Nanpiaophyllum, a genus originally described by Zhang et Zheng (1984) from the Late Triassic Laohugou Formation in the Jinlingsi-Yangshan Basin of western Liaoning Province. The taxonomic affinity of this genus remains uncertain, yet globally this genus has so far been reported only from the Heishanyao and Laohugou formations. Morphological analysis and comparison with extant plants indicate that Nanpiaophyllum was aquatic. Considering the overall composition of the fossil plant assemblage, the Heishanyao Flora is interpreted as having grown in a humid lacustrine-swamp environment under a temperate climate with seasonal variations. This flora is a mixed assemblage dominated by northern-type elements but also including some southern-type components. The rediscovery of Nanpiaophyllum in Hebei Province supports a Late Triassic age for the Heishanyao Formation, enriches the local fossil record of plant diversity, provides new material for studying the ecotype of Nanpiaophyllum, and offers significant evidence for paleogeographic and paleoenvironmental reconstructions.