An eucryphiaceous fruit and leaves from the basal section of the Ñirihuau Formation (Upper Oligocene?-Lower Miocene), Río Negro Province, Argentina

PASSALIA, M.G.

General Roca

Congreso; 11° Congreso de la Asociación Paleontológica Argentina; 2016

Asociación Paleontológica Argentina

The fossil flora preserved in the basal section of the Ñirihuau Formation (Upper Oligocene?-Lower Miocene) includes a high participation of the woody dicot Nothofagaceae, followed by Myrtaceae, Proteaceae and probably Lauraceae, Cunoniaceae and Monimiaceae among others. A number of conifers (Araucariaceae and Podocarpaceae) and ferns (Cyatheaceae, Dicksoniaceae, Polypodiaceae) are also present. Here, an Eucryphia-like fruit and leaves from Pico Quemado locality, Río Negro Province are reported. The fruit consists of the compression of a septicidally dehiscent capsule, mature, partially open, with around 8-10 valves attached to a receptacle and with the pedicel partially preserved. In the same beds, it has been recognized a number of a compound imparipinnate leaves nano- to microphyll, with up to five leaflets lepto- to nanophyll, with toothed margin and craspedodromous venation. Although with a minor size, the fossil leaves share several physiognomic and venation features with those of the extant Patagonian species Eucryphia glutinosa (Prepp. et Endl.) Baill. 1869 (Cunoniaceae). Previous eucryphiaceous fossil records are scarce and include some leaves, woods, capsules and dispersed pollen. They have been reported from the Paleocene ̶ Eocene of Seymour Island (Antarctica), the Late Paleocene ̶ Pleistocene of south-eastern Australia, and the Middle Eocene of Patagonia. Today, Eucryphia Cav. 1797, consists of seven species with a disjunct distribution in southern (mostly temperate) forests of Australia and Chile/Argentina, characterizing in these two latter the so-called Valdivian rainforest.