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

Menispermaceae are a pantropical and temperate family with an extensive fossil record during the Paleogene period, especially in North America Europe, but much less evidence from Asia. The latest indicates succession of tropical to subtropical flora on central Tibetan Plateau Paleogene. However, biogeographic histories these floras still unresolved. Here, we report endocarps leaves Middle Eocene Jianglang village, Bangor County, Plateau. belong two genera: Stephania, which is characterized by horseshoe-shaped endocarp one lateral crest ornamented spiny rectangular ribs, condyle area; Cissampelos (s.l.), has characteristic ridges conspicuous external condyle. Associated genus Menispermites, actinodromous primary venation, brochidodromous secondary veins, entire margins, presence marginal veins. history complex, new fossils early diversification group Asia, probably response warming climate Eocene. appears be part boreotropical flora, connecting Asia American European modern distribution menispermaceous taxa found Jianglang, as well other families represented show that occurred Tibet.