LACUSTRINE BIOTIC ASSEMBLAGES IN THE EARLY

ARCUCCI, A.; PRAMPARO, M. B.; CODORNIU, L.; GIORDANO, P.G.; CASTILLO ELIAS, G.; PUEBLA, G.G.; MEGO, N.; GOMEZ, M.; BUSTOS ESCALONA, E.

Mendoza

Congreso; 4th International Paleontological Congress; 2014

International Palaeontological Association

formations, La Cantera and Lagarcito, with lacustrine facies with well-preserved fossils that could be considered as Konservat-Lagerstätten. The fossil record of the La Cantera Formation includes a variety of palynomorphs (pollen grains and spores) and plant remains (leaves, stems, reproductive structures like cones, seeds and flowers) from Bryophyta, ferns, Gnetales, Gymnospermae and Angiospermae. The palynoflora is dominated by aquatic forms (freshwater algae), which represent more than 80% of the total population. Classopollis and plicate grains (Ephedra type) are also abundant. Among the angiosperms, Afropollis, Retimonocolpites, Stellatopollis, Clavatipollenites, Tucanopollis, Pennipollis and Asteropollis complex are recorded. The bryophyte association constitutes one the most complete records of its type in Argentina. The association of fossil leaves and pollen grains from the La Cantera Formation is one of the most ancient and complete records of first angiosperms in South America, being Late Aptian in age. The Lagarcito Formation yielded a palynoflora dominated by gymnosperm elements (mainly polyplicate and rimulate grains). The aquatic forms are also abundant. Reyrea polymorphus, identified in the association, is an excellent marker for the Aptian-Albian of northern Gondwana. The arthropod remains in both units include Ostracoda and Conchostraca with several endemic species. The insects from the La Cantera Formation, though fragmentary, allow the identification of five different orders and three endemic species of aquatic insects, belonging to the Families Notonectidae and Corixidae, including the oldest member of the Anisopinae subfamily. The actinopterygian fishes were abundant in both paleolakes, but the associations show different taxonomic composition. The Pleuropholid fishes from the Lagarcito Formation are the only record of this rare group in Argentina and the second from South America. Pterodaustro guinazui, the only and unique species of Pterosauria from the Lagarcito Formation, is present with a collection of hundreds of bones. This occurrence is one of the few fossil accumulations of pterosaur remains worldwide from which it is possible to study the details of life history, parameters like growth patterns, and ontogenetic development. This high paleobiodiversity needs to be assessed with respect to sedimentology and lake type to understand the stratigraphic relationships between the two formations and the paleoenvironmental processes preserving these fossils. Konservat-Lagerstätten. The fossil record of the La Cantera Formation includes a variety of palynomorphs (pollen grains and spores) and plant remains (leaves, stems, reproductive structures like cones, seeds and flowers) from Bryophyta, ferns, Gnetales, Gymnospermae and Angiospermae. The palynoflora is dominated by aquatic forms (freshwater algae), which represent more than 80% of the total population. Classopollis and plicate grains (Ephedra type) are also abundant. Among the angiosperms, Afropollis, Retimonocolpites, Stellatopollis, Clavatipollenites, Tucanopollis, Pennipollis and Asteropollis complex are recorded. The bryophyte association constitutes one the most complete records of its type in Argentina. The association of fossil leaves and pollen grains from the La Cantera Formation is one of the most ancient and complete records of first angiosperms in South America, being Late Aptian in age. The Lagarcito Formation yielded a palynoflora dominated by gymnosperm elements (mainly polyplicate and rimulate grains). The aquatic forms are also abundant. Reyrea polymorphus, identified in the association, is an excellent marker for the Aptian-Albian of northern Gondwana. The arthropod remains in both units include Ostracoda and Conchostraca with several endemic species. The insects from the La Cantera Formation, though fragmentary, allow the identification of five different orders and three endemic species of aquatic insects, belonging to the Families Notonectidae and Corixidae, including the oldest member of the Anisopinae subfamily. The actinopterygian fishes were abundant in both paleolakes, but the associations show different taxonomic composition. The Pleuropholid fishes from the Lagarcito Formation are the only record of this rare group in Argentina and the second from South America. Pterodaustro guinazui, the only and unique species of Pterosauria from the Lagarcito Formation, is present with a collection of hundreds of bones. This occurrence is one of the few fossil accumulations of pterosaur remains worldwide from which it is possible to study the details of life history, parameters like growth patterns, and ontogenetic development. This high paleobiodiversity needs to be assessed with respect to sedimentology and lake type to understand the stratigraphic relationships between the two formations and the paleoenvironmental processes preserving these fossils.