![]() ![]() Furthermore, these trees including the type tree obviously lack the community context. Beside this stand, a couple of old isolated individuals are known but not confirmed as native. Due to the supposed loss of populations in historical time by human activities, native stands are extremely rare therefore, they could most likely not exhibit the most characteristic habitat conditions and the specific plant community in which the relic conifer likely grew. The main population of about 30–40 trees in a 25 × 1.5 km zone occurs in the Shui-sha-ba Valley, Zhonglu Town, Lichuan County, Hubei Province (LePage et al., 2005). 800 km 2 under humid conditions (Chu and Cooper, 1950, LePage et al., 2005, Leng et al., 2007), and is similar to habitats of many relic plants in China (Huang et al., 2015). Commonly accepted as native forests with Metasequoia are occurrences in the border of the Hubei, Hunan provinces and Chongqing Municipality (Fig. glyptostroboides was widely planted around the world. The only living species of Metasequoia glyptostroboides Hu et W.C.Cheng (dawn redwood, a famous ‘Living fossil’) was first discovered in Lichuan County, Hubei Province, Central China (Hu and Cheng, 1948). The youngest fossil record of Metasequoia was found in the latest early Pleistocene of Japan (Momohara, 1994, Momohara, 2005). Beginning with the Eocene–Oligocene transition cooling, and markedly during the Plio-Pleistocene climatic decline, Metasequoia retreated from the high latitude parts of its distribution areas, only remaining in the mid latitudes in East Asia (Liu et al., 2007). Metasequoia had a wide distribution range from mid latitudes to the Arctic Circle during the Paleocene–Eocene Thermal Maximum (Leng and Yang, 2009). Later on, it became a common, occasionally predominant component, in many floras of the Northern Hemisphere (Yang and Jin, 2000, LePage et al., 2005). Based on fossil records, Metasequoia first appeared in the Late Cretaceous (LePage et al., 2005). Metasequoia was established based on fossils from the late Miocene of Japan by Miki (1941), but the type of the extant species has priority over the fossil type according to nomenclatural rules (McNeill et al., 2012). The genus is well-known for its rich fossil records with more than 500 sites in the Northern Hemisphere ranging from the Late Cretaceous to the Pleistocene (Fig. The genus Metasequoia Hu et W.C.Cheng of the Cupressaceae is a paragon for biogeographic evolution during the Cenozoic followed by a relic distribution area at present. Therefore, it is of great interest to explore the biogeographic history of conifers from the perspective of paleoenvironmental and paleoclimatic changes in the geological past, to better understand processes and mechanisms controlling the spatial distribution patterns of coniferous plants. Among them, many living groups of conifers that were once widely distributed and then became restricted to small areas at the present day (Farjon, 2013). Even with much less species diversity compared to angiosperms, conifers have a quite long evolutionary history which can be dated back to the Pennsylvanian (Scott and Taylor, 1983, Taylor et al., 2009). There are ~ 70 genera and ~ 627 species of living conifers distributed widely in the world (Farjon, 2008). Together with other evidence, it is concluded that the disappearance of Metasequoia from Southwest China might be related to the evolutionary stasis of Metasequoia, most likely preventing necessary adaptations of the plants to increasing winter and spring aridity induced by the intensification of the Asian monsoon in this region during the Neogene. Furthermore, possible reasons for its disappearance in Southwest China are discussed. ![]() glyptostroboides) considerably expands the spatial distribution range of Metasequoia in the geological past. The material documents obviously a long lasting morphological stasis within the genus. glyptostroboides, we identify them as Metasequoia sp. ![]() Judging by the great morphological similarity between these fossils and extant M. Here, we describe leaves including cuticles and ovuliferous cones from the middle Miocene of Zhenyuan, Yunnan, Southwest China, comprising the southernmost fossil record of the genus worldwide. Historically, the genus Metasequoia Hu et W.C.Cheng has rich fossil records from the Cretaceous to the Pleistocene in the Northern Hemisphere, but fossil records of Metasequoia in China are still rare, which limits our knowledge of its biogeographic history under paleoenvironmental changes. Metasequoia glyptostroboides Hu et W.C.Cheng (Cupressaceae) is a relic plant with a narrow natural distribution in central China. ![]()
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