info:eu-repo/semantics/article
The fossil flip-leaves (Retrophyllum, Podocarpaceae) of southern South America
Fecha
2017-09Registro en:
Wilf, Peter; Donovan, Michael P.; Cúneo, Néstor Rubén; Gandolfo, María A.; The fossil flip-leaves (Retrophyllum, Podocarpaceae) of southern South America; Botanical Society of America; American Journal of Botany; 104; 9; 9-2017; 1344-1369
0002-9122
CONICET Digital
CONICET
Autor
Wilf, Peter
Donovan, Michael P.
Cúneo, Néstor Rubén
Gandolfo, María A.
Resumen
PREMISE OF THE STUDY: The flip-leaved podocarp Retrophyllum has a disjunct extant distribution in South American and Australasian tropical rainforests and a Gondwanic fossil record since the Eocene. Evolutionary, biogeographic, and paleoecological insights from previously described fossils are limited because they preserve little foliar variation and no reproductive structures. METHODS: We investigated new Retrophyllum material from the terminal Cretaceous Lefipán, the early Eocene Laguna del Hunco, and the early/middle Eocene Río Pichileufú floras of Patagonian Argentina. We also reviewed type material of historical Eocene fossils from southern Chile. KEY RESULTS: Cretaceous Retrophyllum superstes sp. nov. is described from a leafy twig, while Eocene R. spiralifolium sp. nov. includes several foliage forms and a peduncle with 13 pollen cones. Both species preserve extensive damage from sap-feeding insects associated with foliar transfusion tissue. The Eocene species exhibits a suite of characters linking it to both Neotropical and West Pacific Retrophyllum, along with several novel features. Retrophyllum araucoensis (Berry) comb. nov. stabilizes the nomenclature for the Chilean fossils. CONCLUSIONS: Retrophyllum is considerably older than previously thought and is a survivor of the end-Cretaceous extinction. Much of the characteristic foliar variation and pollen-cone morphology of the genus evolved by the early Eocene. The mixed biogeographic signal of R. spiralifolium supports vicariance and represents a rare Neotropical connection for terminal-Gondwanan Patagonia, which is predominantly linked to extant Australasian floras due to South American extinctions. The leaf morphology of the fossils suggests significant drought vulnerability as in living Retrophyllum, indicating humid paleoenvironments.