RESUMO A idade Chapadmalalan (Plioceno) é caracterizada por uma grande diversidade dos Glyptodontidae. A maioria dos táxons é reconhecida a partir de carapaças dorsais parciais e/ou tubos caudais, enquanto que as principais características diagnósticas estão relacionadas com a morfologia particular das superfícies expostas dos osteodermas. Algumas espécies são importantes sob o ponto de vista biogeográfico. O Chapadmalalan Superior é baseado na biozona de Paraglyptodon chapadmalensis. Uma reavaliação do material tipo e referido, aliado a novos achados procedentes das formações Chapadmalal e El Polvorín, indica que a diversidade de Glyptodontidae é menor do que se supunha. A morfologia particular das superfícies expostas dos osteodermas utilizada para a caracterização de algumas espécies na realidade se deve a alterações tafonômicas, que resultaram em um padrão de ornamentação não real. Assim, o Glytodontinae P. chapadmalensis deve ser substituído como fóssil guia, uma vez que nem essa espécie nem as incluídas nos gêneros Urotherium, Trachycalyptus e Lomaphorus são bem caracterizadas. Levando-se em conta a diversidade dos Glyptodontidae para esse intervalo, os Glyptodontinae são muito raros (contrastando com a sua abundância no Pleistoceno), enquanto que Eosclerocalyptus, "Plohophorini" (Plohophorus) e Doedicurinae (cf. Eleutherocercus antiquus) são os táxons mais registrados.

ABSTRACT A large diversity of Glyptodontidae has been proposed as characterizing the Chapadmalalan Age (Pliocene). Most of these taxa were recognized on the basis of partial dorsal carapaces and/or caudal tubes, whereas the main diagnostic characteristic is a particular morphology of the exposed surface of the osteoderms. From a biostratigraphic point of view some species are biostratigraphically important. The Upper Chapadmalalan is based on the Paraglyptodon chapadmalensis biozone. Both the re-evaluation of the type and referred materials and new significant findings from the Chapadmalal and El Polvorín Formations indicate that the diversity of Pliocene Glyptodontidae is more limited than previously supposed. The particular morphology of the exposed surface of the osteoderms that characterizes some of the species actually corresponds to a taphonomic alteration, which results in a non-real ornamentation pattern. Thus, the Glyptodontinae P. chapadmalensis must be replaced as a fossil guide because neither this species nor the species included in the genera Urotherium, Trachycalyptus and Lomaphorus are well characterized. Taking into account the diversity of Glyptodontidae for this lapse, the Glyptodontinae are very scarce (a situation that contrasts with its records in the Pleistocene), whereas Eosclerocalyptus, "Plohophorini" (Plohophorus) and Doedicurinae (cf. Eleutherocercus antiquus) are among the most recorded taxa.

The coastal cliffs of Mar del Plata are of the more complete localities of the Southamerican Quaternary, with significant differences in the stratigraphy between the northern and southern flanks. The Plio-Pleistocene record is composed by an almost uniform sequence of coarse silt and very fine sand transported to the area by eolian processes although the last imprint denotes very characteristic fluvial processes. Chapadmalal Formation is located at the toe of these cliffs and is overlapped by an extended caliche level that is the base of the fluvial deposit recognized as Barranca de Los Lobos, Punta Vorohué and Punta San Andrés units. To the top, Miramar Formation shows an increase in the gravity-dominated phenomena and transport of caliche pebbles. During the upper Pleistocene, the accommodation space had diminished towards the southern flank while to the north there was plenty of accommodation space for the aggradation of meandering rivers and the infilling of shallow lakes.

Los acantilados marinos de Mar del Plata representan una de las localidades más completas del Cuaternario sudamericano con diferencias significativas en la estratigrafía entre los del norte y los del sur. El registro plio-pleistoceno está compuesto de una sucesión loessoide casi uniforme de limos gruesos y arenas muy finas transportados a la región por procesos eólicos pero redepositados por procesos fluviales que le imprimieron características muy distintivas. La Formación Chapdamalal se ubica en la base de estos acantilados y culmina con un nivel de tosca muy extendido que representa la base de depósitos fluviales con nombres formacionales Barranca de Los Lobos, Punta Vorohué y Punta San Andrés. Hacia el tope, la Formación Miramar significó una reactivación del paisaje con aumento de los procesos debidos a la pendiente y transporte de clastos de tosca. Durante el Pleistoceno superior, el espacio de acomodación había disminuido hacia el sur mientras que hacia el flanco norte había suficiente espacio para la agradación de ríos meandriformes y colmatación con depósitos de lagunas.

The sediments informally called "pampeanos" are recognized as a package of silts and sandy silts deposited from the Upper Pliocene to Upper Pleistocene, interfingered with two transgressions to the east, discriminated by shells concentrations: the Interensenadan and the Belgranian transgressions. To the west of the Buenos Aires province, an extended area with dunes was called Sand Sea. Within channels excavated in Daireaux, and sea cliffs from Centinela del Mar, mesoscale crossbeding were described probing the presence of sand fields overlaid by silt deposits. Upper Pleistocene ages were confirmed by the assemblages of vertebrate remains. In Centinela del Mar, the age of these transverse dunes that are composing a littoral barrier was also confirmed in their relation to the maximum sea level highstand reached during the Sangamon interglacial (Upper Pleistocene; 120,000 years BP).

Los sedimentos denominados informalmente "pampeanos" son reconocidos como un paquete de limos y limos arenosos depositados desde el Plioceno superior hasta el Pleistoceno superior, con dos intercalaciones marinas hacia el este, reconocidas fundamentalmente por acumulaciones de valvas marinas: el Interensenadense, y el Belgranense. En el oeste de la provincia de Buenos Aires una extensa área ha sido denominada Mar de arena. En canales próximos a Daireaux y en acantilados marinos de Centinela del Mar, se describieron depósitos arenosos con estratificación diagonal de mesoescala que prueban la presencia de campos de arena por debajo de los depósitos limosos. Las edades del Pleistoceno superior han sido confirmadas por las asociaciones de vertebrados recuperados. En Centinela del Mar, la edad de estos médanos transversales que conformaban una barrera litoral ha sido también confirmada por su vinculación con el máximo nivel del mar alcanzado durante el interglacial Sangamon (Pleistoceno superior, 120.000 años AP).