The first spinicaudatan (Crustacea: Diplostraca) from Permo-Triassic continental sequences of South America and its palaeoecological context

Abstract

Tassi, L.V., Monti, M., Gallego, O.F., Zavattieri, A.M. & Lara, M.B., 2013. The first spinicaudatan (Crustacea:Diplostraca) from Permo-Triassic continental sequences in South America and its palaeoecological context. Alcheringa 37, 187–199. ISSN 0311-5518. Cornia martinsnetoi sp. nov., the first spinicaudatan from Permian–Triassic continental sequences of southern South America, is described. The new species has characters diagnostic of the typical late Palaeozoic–Early Triassic subfamily Vertexiinae from Gondwana. This new taxon was found in tuffaceous siltstones in the upper part of the Quebrada de los Fósiles Formation (Puesto Viejo Group), which may span the Permo-Triassic boundary in Argentina. The lower and coarser-grained interval of the Quebrada de los Fósiles Formation was deposited in distal alluvial fans and low- to high-sinuosity rivers. The upper fine-grained interval of this formation, which hosts the spinicaudatans and associated fossils (ostracods, megaspores, fish scales), was deposited in shallow floodplain lakes. Intense volcanic activity influenced the sedimentary evolution of this succession and was accompanied by aridification and some climatic seasonality that likely generated stressful conditions for the biota. Previous biostratigraphic studies support an Early Triassic age for the beds containing Cornia martinsnetoi sp. nov. [Lara Vaz Tassi [larinhatassi@hotmail]com], Área Paleontología (Centro de Ecología Aplicada del Litoral—Centro Científico Tecnológico Nordeste—Consejo Nacional de Investigaciones Científicas y Técnicas), Casilla de Correo 128, 3400 Corrientes, Argentina; Mariana Monti [marimontivaldes@yahoo.com.ar], Departamento de Geología, Museo de Historia Natural de San Rafael—Parque Mariano Moreno s/n°, 5600 San Rafael, Mendoza, Argentina; Oscar Florencio Gallego [ofgallego@live.com.ar], Micropaleontología (Facultad de Ciencias Exactas y Naturales y Agrimensura—Universidad Nacional del Nordeste), Corrientes, Argentina and Área Paleontología (Centro de Ecología Aplicada del Litoral—Centro Científico Tecnológico Nordeste—Consejo Nacional de Investigaciones Científicas y Técnicas), Casilla de Correo 128, 3400 Corrientes, Argentina; Ana María Zavattieri [amz@mendoza-conicet.gov.ar], Laboratorio de Paleopalinología (Instituto Argentino de Nivología y Glaciología y Ciencias Ambientales—Centro Científico Tecnológico—Consejo Nacional de Investigaciones Científicas y Técnicas), Casilla de Correo 131, 5500 Mendoza, Argentina; Maria Belén Lara [lara.maria.belen@live.com.ar], Área Paleontología (Centro de Ecología Aplicada del Litoral—Centro Científico Tecnológico Nordeste—Consejo Nacional de Investigaciones Científicas y Técnicas), Casilla de Correo 128, 3400 Corrientes, Argentina. Received 3.5.2012; revised 22.8.2012; accepted 11.9.2012.