中国科学院南京地质古生物研究所机构知识库

Premise of research.Discovery of abundant leafy twigs with attached pollen cones and seed cones of Austrohamia acanthobractea from the Middle Jurassic Daohugou Lagerstatte in Inner Mongolia, Northeast China, provides detailed morphological and anatomical features of the species, permitting a whole-plant reconstruction and a more detailed evaluation of the affinities of this extinct plant within the Cupressaceae.Methodology.All fossil plants were studied with standard paleobotanical preparations and descriptive terminology.Pivotal results.Austrohamia acanthobractea has leafy twigs consisting of helically arranged, linear leaves with two narrow stomatal bands on the abaxial surface. Pollen cones are borne in the axil of a lanceolate bract, subterminally on shoots in clusters of four, with peltate microsporophylls. Seed cones are borne terminally or laterally, solitary or in a pair, with numerous spirally arranged bract-scale complexes. The bract-scale complex apparently lacks a free ovuliferous scale. Seeds are obovate and inverted, with two narrow lateral wings. Austrohamia acanthobractea bears a close resemblance to extant Taiwania and Cunninghamia.Conclusions.The morphological cladistic analysis suggests that the two species of Austrohamia form a polytomy with the expanded Cunninghamioideae clade, which includes extant Cunninghamia and Cunninghamia-like fossils from the Jurassic, Cretaceous, and Cenozoic. It supports the original interpretation that the genus is closely related to Cunninghamia and Cunninghamia-like fossils based on material from the Early Jurassic of Patagonia in Argentina.