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

PETRULEVICIUS J. F.

Terrestrial Arthropod Reviews

Brill

Año: 2013 vol. 6 p. 53 - 60

1874-9828

Odonata are beginning to be well recorded in the Eocene of Patagonia, Argentina. They are represented by body fossils and traces. Oviposition marks 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, such as as environmental, taphonomical and/or sampling bias. The Laguna del Hunco is well sampled and the absence of nymphs seems to depend on taphonomical factors since there are other preimaginal aquatic inhabitants of the lake, such as Trichoptera nymph cases. The Confluencia site has not been well sampled and adults could be absent due to a sampling bias. The nymphs of Confluencia indicate a water body with low energy flux. Oviposition marks 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 at the Laguna del Hunco site are interpreted to be signals of predation probably by birds or mammals.