Diversity of Menispermaceae from the Paleocene and Eocene of South China

Abstract

We present here the earliest known Asian fossil records of the Menispermaceae based on fossil fruits from Paleocene and Eocene localities in South China. A new genus and species, Paleoorbicarpum parvum sp. nov., and two new species of Stephania Loureiro, S. ornamenta sp. nov. and S. geniculata sp. nov., are recognized from Paleocene deposits of the Sanshui Basin, Guangdong, and a new occurrence of the widespread Eocene species Stephania auriformis (Hollick) Han & Manchester is recognized from the Maoming Basin, Guangdong. The Paleocene Stephania specimens described here represent the earliest fossil endocarp record of the Menispermaceae in eastern Asia. This discovery shows that the moonseed family had arrived in tropical and humid South China by at least the middle Paleocene, which provides important evidence for the origin and phytogeographic history of the family.

New Eocene fossil fruits and leaves of Menispermaceae from the central Tibetan Plateau and their biogeographic implications

“…The rate of endemism of Stephania in China is high, with more than half of the species of this group present only in that area region today. Our fossils from Tibet, in addition to fossils from the Paleogene of Sanshui Basin, Guangdong Province (Han et al, 2020) and Nanning Basin, Guangxi Province (Han et al, 2018), indicate an early diversification of the group in China probably linked to a wider geographic range of the genus during the Paleocene and Eocene. To our knowledge, no fossil record of Stephania has been found from the Oligocene.…”

“…The fossil records from the Cretaceous are almost exclusively based on leaves, which are considered ambiguous (Jacques, 2009b) and do not allow us to understand the origin of Menispermaceae. During the Paleocene, this group was already widely dispersed and diversified in both Gondwana and Laurasia (Jacques, 2009b;Jud et al, 2018, Han et al, 2020. Therefore, Menispermaceae probably spread quickly worldwide, so masking the origin of the group.…”

“…The discovery of Stephania psittaca from the early Paleocene of Argentina (Jud et al, 2018) and S. palaeosudamericana from the Paleocene of Colombia (Herrera et al, 2011) might indicate that Stephania first occurred in Gondwana and subsequently dispersed into Laurasia. However, Stephania geniculata and Stephania ornamenta were described from the Middle Paleocene of China (Han et al, 2020). Therefore, Stephania was already diversified and widespread during the Paleocene in both Gondwana and Laurasia, making it difficult to trace their origin and migration paths.…”

“…These fossil records provide a paleobiogeographic history of the family and also allow testing of biogeographic scenarios based on molecular data (e.g., Wang et al, 2012). These fossils highlight a more complex history than expected (Jud et al, 2018;Han et al, 2020).…”

“…The fossil record of Menispermaceae is abundant and is mainly recognized not only by endocarp remains, but also by leaves, wood and pollen grains (Doria et al, 2008;Jacques, 2009b). Abundant fossil records occur during the Paleogene and cover a large geographic region: North America (e.g., Wolfe, 1977;Manchester, 1994;Tiffney, 1999), South America (Doria et al, 2008;Herrera et al, 2011;Jud et al, 2018), Europe (e.g., Reid & Chandler, 1933;Fairon-Demaret & Smith, 2002;Jacques & De Franceschi, 2005;Collinson et al, 2012), and Asia (Manchester et al, 2005;Liu & Jacques, 2010;Han et al, 2018Han et al, , 2020. These fossil records provide a paleobiogeographic history of the family and also allow testing of biogeographic scenarios based on molecular data (e.g., Wang et al, 2012).…”