Faunistic changes between the Middle/Late Pleistocene and the Holocene on the

GORDILLO SANDRA; ISLA

QUATERNARY INTERNATIONAL

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2011 vol. 233 p. 101 - 112

1040-6182

The  marine  terraces  located  on  the  atlantic  coast  of  Tierra  del  Fuego  (Argentina)  were  previouslyassigned to different sea-level highstands from the Middle Pleistocene to the Holocene. This study isfocused on the analysis of the mollusc assemblages recovered from those terraces. When comparingMiddle/Late Pleistocene mollusc assemblages with adjacent Holocene/modern ones, ecological changesin  the  fauna  were  recognized.  The  Pleistocene  assemblages  are  less  diverse  and  are  dominated  byinfaunal bivalves, whereas Holocene and modern assemblages are more diverse and are dominated byepifaunal taxa, with a higher presence of gastropods. However, on a biogeographic scale, the fact thatPleistocene taxa (with the probable exception of Retrotapes sp.) are living today in the region is attributedto the location of the study sites, at the centre of the Magellan biogeographic unit, with species far awayfrom the edges of their ranges of distribution. Regional faunistic changes and the local disappearance ofRetrotapes in post-glacial benthic communities in the area are therefore interpreted on the basis ofregional and local causes, most probably associated to substrate changes, and not on a global trendrelated to large-scale patterns.