Unlike animals, which may migrate to more favorable places to live or modifytheir behaviors if the environmental conditions change, plants normally cannotchoose similar strategies. Alternatively the plants have mechanisms of rapid morphological and adaptive changes which make them a useful source of information on the effects of ecological constraints (so true ecotypes sensu Margalef 1983). By analogy, plant fossils may be an important tool to reconstruct the past climates. Furthermore, the floras are in general prevented in their dispersion by the oceanic barriers (with few exception like proposed by Pole 1994), and represent an important source for paleogeographical reconstructions. Evidence of Late Cretaceous (Coniacian to Maastrichtian) Antarctic terrestrial faunas are documented exclusively in the NE flank of the Antarctic Peninsula, West Antarctica (Reguero and Gasparini 2007; Reguero et al. submitted) (Fig. 5.8). Late Cretaceous deposits of the James Ross Basin have been extensively surveyed by vertebrate paleontologists; most collections consist of marine reptiles (del Valle et al. 1977; Gasparini et al. 1984; Chatterjee and Small 1989; Martin et al. 2002; Novas et al. 2002; Martin 2006; Martin and Crame 2006; de la Fuente et al. 2010) and other marine vertebrates (Woodward 1908; Cione and Medina 1987; Grande and Chatterjee 1987; Richter and Ward 1990; Stahl and Chatterjee 1999, 2002; Kriwet et al. 2003; 2006). In contrast there have been fewer findings of Cretaceous terrestrial vertebrates, which correspond only to avian and non avian dinosaurs. The first Late Cretaceous terrestrial fossil vertebrates reported from Antarctica came from the James Ross Basin (Gasparini et al. 1987).

Fil: Acosta Hospitaleche, Carolina Ileana Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento de Paleontología Invertebrados; Argentina

Fil: Reguero, Marcelo Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento de Paleontología Invertebrados; Argentina

Fil: Goin, Francisco Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento de Paleontología Invertebrados; Argentina

Fil: Marenssi, Sergio Alfredo. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Fil: Dutra, Tania. Universidad de Vale do Rio dos Sinos; Brasil