*4.3.1 Interglacials* ≥ *MIS 9 and MIS 7*

These two interglacials recorded in area D were not recorded in the northeast of BAP. In areas A-C, a total of nine species of mollusks were recorded in the

**Figure 3.** *Paleoecological features of all regions (A–D) in interglacial MIS 5e.*

#### **Figure 4.** *Paleoecological features of all regions (A–D) in interglacial MIS 1.*

**Figure 5.** *Paleoecological features of all regions (A–D) in modern beaches.*

**Figure 6.** *Paleoecological features of region D in interglacial MIS 7.*

Interglacial ≥ MIS 9, and among them, there is 50–67% of warm water species of bivalves, being this the oldest record of marine mollusks for the BAP. In MIS 7 analyzed in area D, a total of 11 species was recorded with 20% of warm water bivalves. Most recorded species in both interglacials still inhabit the modern coasts of Argentina, except for the gastropod *Tegula atra*, absent since the MIS 1.

Both interglacials (≥MIS 9 and MIS 7) revealed the presence of warm water mollusks which are not recorded in the marine deposits of the northeast of BAP where these deposits have not been preserved [124]. The record of these interglacials in the BAP is a novelty in the analysis of gastropods and

#### *Quaternary Marine Mollusk Associations of the Last Interglacials in North Patagonia… DOI: http://dx.doi.org/10.5772/intechopen.99221*

bivalves. Whereas Aguirre et al. [27, 28] reported that in the coasts of southern Patagonia, in areas such as Bahía Vera-Camarones (44.2° to 45°S) and Bahía Bustamente-Caleta Olivia (44.9°–45.3°S, Chubut Province, Argentina), the environmental conditions (substrate, depth, and energy conditions) during the late Pleistocene (MIS 7 and MIS 5e) suggest SST similar to those of the modern littoral and even slightly higher than present, recording faunas of warm to temperate waters.
