Palaeoenvironmental and palaeoecological implications from body fossils and ovipositions of Odonata from the Eocene of Patagonia, Argentina

PETRULEVICIUS J. F.

Congreso; VI International Congress on Fossil Insects, Arthropods and Amber; 2013

Odonata are beginning to be well recorded in the Eocene of Patagonia. They are represented by body fossils and traces. Ovipositions are recorded in Río Pichileufú (Lutetian: 47.7 Ma; Río Negro province) and Laguna del Hunco (Ypresian: 52.2 Ma; Chubut province), nymphs in Confluencia (Ypresian?; Río Negro), and adults (wings) in Laguna del Hunco. The absence of different stages in given localities could depend on different factors as environmental, taphonomical and/or sampling bias. Laguna del Hunco is well sampled and absence of nymphs seems to depend on taphonomical factors since there are other preimaginal aquatic inhabitants of the lake as Trichoptera nymph cases. Confluencia is not well sampled and adults could be absent due to a sampling bias. The nymphs of Confluencia indicate a water body with low flux of energy. Ovipositions in Laguna del Hunco and Río Pichileufú are made on terrestrial leaves of bushes and trees and have three different morphologies. Leaves are interpreted to be alive when oviposition was done as they show tissue reactions associated to the injuries. Wrinkled wings of LH are interpreted to be signals of predation probably by birds or mammals.