Caption: This is foliage of Papuacedrus prechilensis (Berry) Wilf et al., comb. nov. (Cupressaceae), from the middle Eocene Río Pichileufú flora of Río Negro Province, Patagonia, Argentina. The monotypic genus Papuacedrus is today restricted to montane rainforests of New Guinea and the Moluccas, but its scarce fossil record includes Tasmania and Antarctica. Wilf et al. describe a suite of well-preserved specimens excavated from early and middle Eocene sites in Patagonia, including an immature seed cone attached to foliage with organic preservation, bearing numerous characters diagnostic of Papuacedrus. The fossils represent the first fossil cone, the oldest record, and the only South American record of Papuacedrus, greatly expanding its history of widespread distribution across Gondwana before cooling and drying conditions forced its extinction in southern South America and retreat to its current range in the equatorial West Pacific. Before the revision here to Papuacedrus, the only previously known fossil of this species was described as a close relative of Austrocedrus chilensis, a dry- and cold-tolerant conifer that grows near the fossil sites. Thus, the revision removes a link to southern South American biomes and puts in its place a link to Australasian montane rainforests. Along with other emerging and consistent data from these floras, this result suggests that a rainforest biome was present in Eocene Patagonia, possibly including topographic relief. High Eocene rainfall, topography, and land connections both to the rest of South America and to Australasia via Antaractica are viable explanations for the extraordinary plant and insect-feeding richness found at the fossil sites. The specimen shown is coalified with light patches of facial leaf cuticle visible overlying coal. Note opposite branching, enlarged lateral leaves, and light-colored amber in foliar resin canals.
Credit: Image credit: P. Wilf.
Usage Restrictions: Give credit as shown above and cite the source article: Peter Wilf, Stefan A. Little, Ari Iglesias, María del Carmen Zamaloa, María A. Gandolfo, N. Rubén Cúneo, and Kirk R. Johnson. Papuacedrus (Cupressaceae) in Eocene Patagonia: A new fossil link to Australasian rainforests. Am. J. Bot. 2009 96: 2031-2047.
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