A new woody stem of Piceoxylon from the Early Cretaceous of Northeast China and its implications for the early diversification of Pinaceae

Abstract

Pinaceae are one of the most economically and ecologically important tree families and play a key role in boreal, temperate, and montane forests of the Northern Hemisphere. The family have a rich fossil record with the earliest occurrence of the Pinaceae crown group probably from the Late Jurassic, and diverse seed cones, woods, leaves, and pollen grains from the Early Cretaceous of the Northern Hemisphere. However, the origin and early evolutionary history of Pinaceae is not well understood, in part because of uncertainty about the phylogenetic position of early fossils. In this article we describe a new woody stem of Pinaceae based on well-preserved material from the Early Cretaceous Huolinhe Formation in Jarud Banner, eastern Inner Mongolia, Northeast China. Piceoxylon jarudense sp. nov. has distinct growth rings with secondary xylem composed of tracheids, ray tracheids, ray parenchyma cells, axial parenchyma cells, and axial and radial resin canals. Pitting on radial walls of tracheids is abietinean; cross-field pitting is piceoid and taxodioid with two to six pits arranged in one to two rows per cross-field. Axial and radial resin canals are lined by thick-walled epithelial cells. Piceoxylon has been considered to include species with wood anatomy comparable to extant Larix, Pseudotsuga, Picea, and Cathaya. Comparisons of wood anatomy and constrained phylogenetic analyses of P. jarudense, one of the earliest records of Piceoxylon, both suggest that P. jarudense is most likely allied with Larix and Pseudotsuga within the pinoid clade suggesting divergence of the Larix–Pseudotsuga clade before ~125.6 Ma.

Keywords

Early Cretaceous / fossil wood / Northeast China / Piceoxylon / Pinaceae

RIGHTS & PERMISSIONS

2025 Institute of Botany, Chinese Academy of Sciences.