Papuacedrus (Cupressaceae) in Eocene Patagonia: A new fossil link to Australasian rainforests

The 51.9 Ma Laguna del Hunco (LH) and 47.5 Ma Río Pichileufú (RP) floras from Patagonia, Argentina are unusually rich, angiosperm-dominated assemblages with living relatives in the low-latitude West Pacific, neotropics, and temperate southern latitudes. The diverse gymnosperms in these floras are im...

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Bibliographic Details
Published in:American journal of botany 2009-11, Vol.96 (11), p.2031-2047
Main Authors: Wilf, Peter, Little, Stefan A, Iglesias, Ari, del Carmen Zamaloa, María, Gandolfo, María A, Cúneo, N. Rubén, Johnson, Kirk R
Format: Article
Language:English
Subjects:
Austrocedrus
Berries
Biodiversity
Biogeography
Botany
Bracts
Conifers
Cupressaceae
Eocene
Epidermal cells
Flora
Flowers & plants
Fossils
Laguna del Hunco
Leaves
Libocedrus
Paleobotany
paleoclimate
Papuacedrus
Patagonia
Plants
Rainforests
Río Pichileufú
Seed cones
subtropical rainforest
Tropical rain forests
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Summary:The 51.9 Ma Laguna del Hunco (LH) and 47.5 Ma Río Pichileufú (RP) floras from Patagonia, Argentina are unusually rich, angiosperm-dominated assemblages with living relatives in the low-latitude West Pacific, neotropics, and temperate southern latitudes. The diverse gymnosperms in these floras are important for Gondwanan biogeographic history and paleoclimatic interpretations. "Libocedrus" prechilensis Berry 1938 (Cupressaceae), previously known only from the holotype (RP), a vegetative branch, is revised here based on new material from both localities, including a seed cone attached to a shoot with cuticle (LH). Characters of these fossils are diagnostic of monotypic Papuacedrus (highlands of New Guinea and Moluccas). Living P. papuana is most abundant in cloud forests receiving up to 4 m rainfall annually, whereas Austrocedrus (Libocedrus) chilensis, the basis of comparison when the fossil species was named, inhabits dry, cold steppe margins to mediterranean climates in southern South America. We establish Papuacedrus prechilensis comb. nov., which simultaneously invalidates a southern South American connection for the fossil floras and reveals a link to West Pacific montane rainforests. Combined evidence indicates a biome similar to extant subtropical, or tropical montane, rainforests that persisted for at least 4.4 Myr, linking elevated floral richness to abundant rainfall.
ISSN:0002-9122
1537-2197
DOI:10.3732/ajb.0900085