Miguel Ángel Zubimendi

Shell variability in Tawera gayi (Veneridae) from southern South America: a morphometric approach based on contour analysis

This study analyses the significance of shell morphological variations in the venerid clam Tawera gayi, a typical element of shallow marine soft bottoms in southern South America and the most common species recovered from Late Quaternary marine deposits along the Beagle Channel, Tierra del Fuego. Fossil and modern Tawera shells from different localities around the southern tip of South America were analysed using the Elliptic Fourier Analysis (EFA) method. Taking into account the palaeontological history of this genus in the southern hemisphere, EFA was also performed on shells of Tawera congeners from South Africa (T. philomela) and New Zealand (T. spissa). The use of EFA permitted the distinction between the three Tawera species and geographical differentiation in the T. gayi groups. These morphological variations of T. gayi appear best related to ecophenotypic plasticity as a response to different environmental conditions, although the palaeobiogeographical history of Tawera in South America cannot be ruled out.

Lestodelphys halli EN LA PROVINCIA DE SANTA CRUZ (ARGENTINA). PRIMER HALLAZGO EN UN SITIO ARQUEOLÓGICO EN LA COSTA PATAGÓNICA

En esta nota nos proponemos tres objetivos. Primero, dar a conocer la presencia de Lestodelphys halli (Thomas 1921) en un sitio de la localidad arqueologica de Punta Medanosa, Provincia de Santa Cruz (Argentina). Segundo, realizar una breve caracterizacion de la especie, asi como una descripcion de los rasgos osteologicos de interes para su determinacion en otros contextos arqueologicos. Tercero, realizar un repaso bibliografico de sitios en los cuales se ha registrado la presencia de L. halli en la Republica Argentina