Fossil moonseeds (Menispermaceae) from the Paleogene of West Gondwana (Patagonia, Argentina)

JUD, N.A.; GANDOLFO, M. A.; ARI IGLESIAS; WILF PETER

ANNALS OF BOTANY

OXFORD UNIV PRESS

Lugar: Oxford; Año: 2018 vol. 105 p. 927 - 942

0305-7364

Premise of the study: The fossil recordis critical for testing evolutionary hypotheses. Menispermaceae (moonseed) area widespread family with a rich fossil record and several alternative hypothesesrelated to their origin and diversification. The family is well-represented inCenozoic deposits of the Northern Hemisphere, but the record in the SouthernHemisphere is sparse. Filling in the southern record of moonseeds will improveour ability to evaluate alternative biogeographic hypotheses.Methods: Fossils were collected from theSalamanca (early Paleocene, Danian) and the Huitrera (earlyEocene, Ypresian) formations in Chubut Province, Argentina. Wephotographed them under light microscopy,epifluorescence, and scanning electron microscopy and compared the fossils withsimilar extant and fossil Menispermaceae using herbarium specimens and publishedliterature.Key results: We describe fossil leavesand endocarps attributed to Menispermaceae from Argentinean Patagonia. Theleaves are identified to the family, and the endocarps are further identifiedto the tribe Cissampelideae. The Salamancan endocarp is assigned to the extant genusStephania. These fossilssignificantly expand the known range of Menispermaceae in South America, andinclude the oldest (64 Ma) unequivocal evidence of the family worldwide. Conclusions: Our findings highlight the importance of west Gondwana in theevolution of Menispermaceae during the Paleogene. Currently, the fossil recorddoes not discern between a Laurasian or Gondwanan origin (or vice versa);however, it does demonstrate that Menispermaceae grew well outside the tropics bythe early Paleocene. The endocarps? affinity with Cissampelideae suggests that diversificationof the family was well underway by the earliest Paleocene.