Insect Egg Ovipositions on Leaves From The Upper Triassic From Northern Chile

GNAEDINGER, S.;; RODRIGUES, K. A.;; GALLEGO, O. F.

Brasil

Simposio; XII SIMPOSIO BRASILEIRO DE PALEOBOTÂNICA E PALINOLOGIA; 2008

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Insect egg ovipositions on leaves from the Upper Triassic from northern Chile   Karen ADAMI RODRIGUES 1, Silvia GNAEDINGER 2 y Oscar F. GALLEGO2       According to recent contributions the knowledge of animal-plant interactions has increased noticeably in the last decade. Such evidences indicate the presence of organisms that are absent from burials and provide exceptional information about ancient ecological relationships. The geological record of the insect ovipositions includes several foundings, which range from the Paleozoic (Carboniferous) through the Cenozoic (Paleogene-Neogene?). This paper reports the first record of Triassic insect egg ovipositions from southern South America. They are recorded on leaves and leaf fragment from Heidiphyllum Retallack, Taeniopteris Brongniart and Pseudoctenis Seward, from the Upper Triassic from La Ternera and Las Breas formations, from northern Chile. These traces are ovate and lenticulate in outline showing the characteristic ovipositor scar, arranged in longitudinal rows, near the leaf base, parallel to the leaf venation/veins. Comparisons morphological characters (shape and size) with other world records and with various oviposition types on plants are made. They are tentatively assigned to the Order Odonatoptera (damselflies) based on the morphologic characteristics, host plants, paleoenvironmetal interpretations of fossil records of those units. The host plants Heidiphyllum were probably a relatively low-growing shrubby voltzialean conifers that formed dominant to monospecific thickets in areas of higher water table on a floodplain, or on sandbars within the braided river channels. Cycadinean as Pseudoctenis and Incertae Sedis Cycadales as Taeniopteris grown as shrub to small tree forest to woodland. And their leaves brought a favourable/suitable place for the oviposition of the ancient odonata.     1. Multidisciplinar, Universidade Federal do Acre, Campus Floresta, Cruzeiro do Sul, Acre-Brasil. florestaczs@hotmail.com, gerarus@hotmail.com 2. Centro de Ecología Aplicada del Litoral-Área de Paleontología-Consejo Nacional de Investigaciones Científicas y Técnicas. Facultad de Ciencias Exactas y Naturales y Agrimensura. Universidad Nacional del Nordeste. Corrientes, Argentina. E-mail: scgnaed@hotmail.com; ofgallego@hotmail.com Centro