Paleoenvironmental interpretation of late Quaternary molluscan assemblages from southern South América: A taphonomic comparison between the Strait of Magellan and the Beagle Channel

Abstract

ABSTRACT. This study analyzes the Holocene molluscan assemblage in raised marine terraces along the coasts of the Strait of Magellan and the Beagle Channel. A total of 33 gastropods and 12 bivalves were identifi ed. They constitute the fi rst mollusk listing for deposits in the Strait of Magellan. Taphonomic analysis suggests a high energy environment with epifaunal elements in the Strait of Magellan and a low energy environment with the predominance of infaunal elements in the Beagle Channel. All the collected species are living taxa suggesting that postglacial climatic variations were not enough to alter the composition of the communities since at least 6,000 yr BP in the southern Chile-Argentina region.

Towards a model of postglacial biogeography in shallow marine species along the Patagonian Province: lessons from the limpet Nacella magellanica (Gmelin, 1791)

“…17 ka [100] while a major and rapid warming period occurred between 14–10 ka [23,100, 101]. Pollen statrigraphic studies in the Beagle Channel and Tierra del Fuego suggest that the disappearance of ice in that sector occurred ~ 11.6 ka [96-102]. Based on our estimations, population expansion in N. magellanica would have occurred ~ 6.3 ka under a sudden growth model and ~ 9.0 ka under the Bayesian Skyline Plot approximation.…”

“…Also, paleontological studies on postglacial mollusk faunas in the northern coast of the Beagle Channel suggest that major expansion of taxa occurred after the glaciers receded fully (~ 10 ka). Under the relatively warmer conditions of the middle Holocene (5.0 to 4.0 ka), the fossil record indicates a process of diversification of several mollusk taxa including Nacella [103-105]. …”

Concerted genetic, morphological and ecological diversification inNacellalimpets in the Magellanic Province

“…2005; Aguirre et al. 2006, 2009; Cárdenas & Gordillo 2009). Using an integrative approach, we observed a complete concordance between morphological and molecular results among Nacella nominal species from the Magellanic Province.…”

“…Furthermore, the fossil record of the genus in this region supports recent diversification. Specimens identified as N. deaurata, N. delicatissima, N. magellanica and N. mytilina were only found in late Pleistocene (<40 kya) and Holocene deposits (Gordillo 1999;Aguirre 2003;Gordillo et al 2005;Aguirre et al 2006Aguirre et al , 2009Cárdenas & Gordillo 2009). Using an integrative approach, we observed a complete concordance between morphological and molecular results among Nacella nominal species from the Magellanic Province.…”

Caracterización paleoambiental y paleodiversidad malacológica en los depósitos marinos cuaternarios del norte patagónico (sur de Buenos Aires y norte de Río Negro)

“…A lo largo de la costa Argentina, distintos autores realizaron estudios sobre asociaciones de moluscos fósiles cuaternarios desde el punto de vista paleoclimático, paleobiogeográfico, paleoecológico, y taxonómico (ej. Farinati, 1978Farinati, , 1985Farinati, , 1994Gordillo, 1992Gordillo, , 1998Aguirre y Whatley, 1995;Aguirre, 2003;Aguirre et al, 2005Aguirre et al, , 2006Aguirre et al, , 2007Gordillo et al, 2008;Gordillo, 2009;Cardenas y Gordillo, 2009;Rabassa et al, 2009, entre otros). La mayor parte de los estudios paleontológicos sobre moluscos marinos en la costa de la Provincia de Buenos Aires, se han concentrado en el Holoceno marino.…”