Mauro G. Passalia

A new early angiosperm leaf from the Anfiteatro de Ticó Formation (Aptian), Santa Cruz Province, Argentina

A new record of angiosperm from Aptian deposits of the Anfiteatro de Tico Formation (basal unit of the Baquero Group), in its type locality, north-center of Santa Cruz province, Argentina is reported. This record integrates the fossiliferous level Williamsonia-Zamites that contains abundant remains of bennettite leaves and was deposited in floodplain facies. The fossil consists of a single leaf imprint, with entire margin and festooned brochidodromous venation of low rank. It has features that define, in part, the nymphaeaphyll morphological type. This type occurs among the most early assemblages having angiosperms (northeastern Brazil, Portugal, South Australia, eastern North America), and is part of a physiognomic-foliar pool associated to taxa considered to be basal within the group. This foliar morphotype, is found in some members of extant angiosperms of usually herbaceous habit, and perhaps, by analogy, this may have been the original habit of our fossil species. The mega floristic record of eocretaceous angiosperms from Southern Hemisphere is scarce. In spite of them, angiosperm foliar remains from other location (Bajo Tigre) of the Anfiteatro de Tico Formation are known. They are different to this new record. This incipient diversity suggests an even (pre-Aptian) presence of the angiosperms in the region.

On the Presence Of the Cycad Pseudoctenis dentata Archangelsky and Baldoni in the Punta del Barco Formation (Late Aptian), Santa Cruz Province, Argentina

In southern South America more than twenty species, referred to the cycad genus Pseudoctenis, have been recorded from Upper Triassic to Lower Cretaceous deposits. However only three, identified from the Baquero Group (Aptian), have cuticle preserved. One of them, Pseudoctenis dentata Archangelsky and Baldoni, from the Anfiteatro de Tico Formation (basal unit of the Baquero Group) is here identified on the basis of well-preserved material collected in the same Group, but in its upper unit (Punta del Barco Formation). This record extends the presence of this taxon in the Cretaceous flora of Patagonia and reinforces the importance of the cuticular features in paleotaxonomical assignations. En el sur de America del Sur mas de veinte especies de Pseudoctenis (Cycadales) han sido registradas en depositos comprendidos entre el Triasico Superior y el Cretacico Inferior. Sin embargo, solo tres especies, pertenecientes al Grupo Baquero (Aptiano), conservan restos de cuticula. Uno de ellos, Pseudoctenis dentata Archangelsky y Baldoni, de la Formacion Anfiteatro de Tico (unidad inferior del Grupo Baquero) se identifica aqui sobre la base de un nuevo especimen bien conservado obtenido en depositos del mismo grupo, pero en su unidad superior (Formacion Punta del Barco). Este registro extiende la presencia de P. dentata en el Cretacico de Patagonia, a la vez que refuerza la importancia de considerar las caracteristicas cuticulares en las asignaciones paleotaxonomicas.

Improntas foliares de la formación La Ollita (Mioceno), Valle del Cura, Cordillera frontal, provincia de San Juan, Argentina

Leaf imprints from the La Ollita Formation (Miocene), Valle del Cura, Cordillera Frontal, San Juan province, Argentina. A monospecific collection of leaf imprints is described. This set belongs to one freshwater angiosperm species corresponding to the Hydrocharitaceae, so that this family must have formed part of the aquatic vegetation in water bodies probably entailing the Paranense sea.