Palaeobotany: Old but new stories on plant diversity

Abstract

Palaeobotanical records can increase our understanding of how extant plant diversity is generated. For example, a fossil plant can serve as an intermediate between two extant plant species with very different forms and can be used to study morphological evolution. As a fossil plant may be important when estimating the divergence time of a specific evolutionary lineage, the identification of informative plant fossils could further improve our understanding of extant plants. Japanese palaeobotany started in 1877 when Hermann T. Geyler reported 12 Mesozoic plant fossils from the foot of Mt. Hakusan, Ishikawa Prefecture, Japan (Geyler 1877). Subsequently, Alfred G. Nathorst published the first comprehensive report on Japanese Tertiary flora in 1883. He described 67 species from the Late Pliocene of Mogi, Nagasaki-shi, Nagasaki Prefecture (Nathorst 1883; see Tanai 1976 for details). These foundational studies on Japanese palaeoflora were conducted by European palaeobotanists, and it was in 1889 that Matajiro Yokoyama published the first palaeobotanical study by a Japanese scientist. He reported 49 species, including 11 new species from the Mesozoic strata distributed in Kaga, Hida, and Echizen (corresponding to the present Ishikawa, Gifu, and Fukui Prefectures, respectively: Yokoyama 1889). Since then, 1,203 species (12 Paleozoic, 379 Mesozoic, and 812 Cenozoic) have been established based on macrofossil specimens collected in Japan (for a summary up to 1999, see Uemura et al. 2002). The Journal of Plant Research (JPR), formerly the Botanical Magazine, Tokyo (BMT), has provided a platform for botany-based palaeobotanical studies (excluding geology-based studies). The first palaeobotanical note appeared in the miscellany of volume 2 (p. 17 of 1888), in which an anonymous editor provided a comment on the phylogenetic position of the Bennetitales by Graf zu Solms-Laubach. Later, Yasushi Suzuki reported permineralized conifers and fungi from the Cretaceous period of Hokkaido, Japan, as a new species (Suzuki 1910, BMT vol. 24). This was the first palaeobotanical article published in the JPR (BMT). By 2013, 72 palaeobotanical studies had been published, and 50 new macrofossil species (2 Paleozoic, 26 Mesozoic, and 22 Cenozoic) had been reported.