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Cuticle ultrastructure of Baiera furcata from Northeast China and its implication in taxonomy and paleoenvironment

Guignard, Gaëtan, Yang, Xiao-Ju, Wang, Yong-Dong
Review of palaeobotany and palynology 2019 v.268 pp. 95-108
Cretaceous period, Ginkgoales, energy-dispersive X-ray analysis, leaves, paleoecology, taxonomy, transmission electron microscopy, ultrastructure, China
A study on the leaf cuticle ultrastructures of Baiera furcata from the Lower Cretaceous Huolinhe Formation in East Inner Mongolia, Northeast China, was conducted with transmission electron microscopy (TEM) and elements analysis by Energy Dispersive Spectroscopy (EDS). TEM observation revealed the ultrastructural details from ordinary epidermal cells for both upper and lower cuticles, and stomatal apparatus, which were all made with A2 (granular) and B1 (fibrilous) layers. Additionally, well-preserved cell remnants were also observed. Comparisons with other cuticles of the Ginkgoales were made using statistical measurements and evaluations of some potential Order characteristics, and genus–species characteristics were also emphasized. Two potential ultrastructural groups can be recognized: Baiera–Sphenobaiera and Ginkgo–Ginkgoites–Pseudotorellia. This is reinforced by EDS element analysis, whereby ratios could also be compared with another closely related Ginkgoalean taxon Sphenobaiera huangii. The paleoenvironment significances is discussed, and it seems to support the TEM and EDS results. It indicates a signature in the cuticle fine details of Sphenobaiera, which has experienced a putatively warmer paleoenvironment than that of Baiera.