Oligocene Desmanthus (Leguminosae) from the Qaidam Basin in northeastern Tibetan Plateau, China, and its implications for paleoclimate and paleoelevation

Megafossils of Betulaceae from the Oligocene of Qaidam Basin and their paleoenvironmental and phytogeographic implications

“…Recent research has revealed that Podocarpium may have originated in East Asia, migrated into the central valley of Tibet in the late Eocene, and then spread westward to Europe ( Li et al., 2022 ). Many fossil samaras and leaves of Ailanthus confucii have been found at the Huatugou fossil site ( Yang et al., 2021a , Yang et al., 2021b ). This is a species that been discovered in Oligocene deposits from Europe to East Asia.…”

“…Desmanthus Willd. (Leguminosae), collected from lower Shangganchaigou Formation, is a pantropical legume genus native to the New World, revealing that the northwestern Qaidam was much warmer in the early Oligocene ( Yang et al., 2021a , Yang et al., 2021b ). A. confucii Unger (Simarubaceae), which was found from a nearby layer and is the most common member among fossil Ailanthus , is thought to have shared a similar ecological niche with extant A. altissima in the past, also indicating that climate conditions at the fossil site were much warmer and more humid during the early Oligocene than currently ( Yang et al., 2021b ).…”

“…The plant records published thus far include Simaroubaceae Candolle, Leguminosae Jussieu, Salicaceae Mirb., and Juglandaceae DC. ex Perleb, and are mainly from the Huatugou area and Dahonggou area, which are located in the northwestern and northern margins of the basin, respectively ( Yan et al., 2018 ; Han et al., 2020 ; Song et al., 2020 ; Yang et al., 2021a , Yang et al., 2021b ). Information on the Paleogene paleovegetation in the basin is still incomplete.…”