Update of the Menispermaceae fossil record: new discoveries and perspectives.

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Rio, Cédric Del

Edité par CCSD -

International audience. Menispermaceae Juss. is a family of climbing plants with a predominantly pantropical and temperate distribution. Commonly known as the "moonseed" family, they are named after the distinctively curved shape of their endocarps, which serve as key diagnostic features for distinguishing among the 72 extant genera. The fossil record of Menispermaceae is extensive, likely reflecting their past high diversity and broader biogeographic distribution during warmhouse periods. Over the past 15 years, numerous new discoveries have emerged, often challenging previous hypotheses and complicating rather than clarifying our understanding of evolutionary processes and biogeographic patterns. This presentation aims to provide a critical analysis of the Menispermaceae fossil record, focusing particularly on the key genera Stephania and Tinospora to address taxonomic and biogeographic issues. The discovery of Early Paleogene endocarps of Stephania from South America and Asia has disrupted the traditional North American–European bias, revealing a more complex biogeographic history throughout the Cenozoic. The present fossil record gives the impression of a sudden widespread appearance of Stephania during the Paleocene. However, the co-occurrence of Menispermaceae leaves unrelated to Stephania at the same fossil sites, along with recent phylogenetic studies, indicates that fossil identifications of Stephania have often been based on plesiomorphic characters. Furthermore, Tinospora has been shown to comprise at least five distinct clades, complicating the placement of fossil endocarps attributed to this genus. As a future perspective, integrating morphological studies of both modern and fossil endocarps with phylogenetic analyses will contribute to refining the biogeographic framework of Tinospora and improving our understanding of its evolutionary history.

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