Sporomorphs and quantitative analysis of the Eocene record from IODP Hole 318-U1356A

The early Eocene epoch was characterized by extreme global warmth, which in terrestrial settings was characterized by an expansion of near-tropical vegetation belts into the high latitudes. During the middle to late Eocene, global cooling caused the retreat of tropical vegetation to lower latitudes. In high-latitude settings, near-tropical vegetation was replaced by temperate floras. This floral change has recently been traced as far south as Antarctica, where along the Wilkes Land margin paratropical forests thrived during the early Eocene and temperate Nothofagus forests developed during the middle Eocene. Here we provide both qualitative and quantitative palynological data for this floral turnover based on a sporomorph record recovered at Integrated Ocean Drilling Program (IODP) Site U1356 off the Wilkes Land margin. Following the nearest living relative concept and based on a comparison with modern vegetation types, we examine the structure and diversity patterns of the Eocene vegetation along the Wilkes Land margin. Our results indicate that the early Eocene forests along the Wilkes Land margin were characterized by a diverse canopy composed of plants that today occur in tropical settings; their richness pattern was similar to that of present-day forests from New Caledonia. The middle Eocene forests were characterized by a canopy dominated by Nothofagus and exhibited richness patterns similar to modern Nothofagus forests from New Zealand.

Abundances and ebridian skeleton contents from IODP Exp302

Abundant and diversified ebridians recovered during IODP Expedition 302 (ACEX) have been identified and counted in order to establish their taxonomy and to decipher the biostratigraphic potential of ebridians in the central Arctic Ocean. In the ACEX samples these fossils are preserved in Lithologic Units 1/6 and 2, which consist mainly of dark silty clay and biosiliceous ooze, respectively. Thirty taxa have been distinguished, three of which are described as new species (Ammmodochium lomonosovense, Pseudammodochium karyon, and pseudammodochium psichion). The most dominant ebridian species is Pseudammodochium dictyoides throughout the biosiliceous section. The second dominant species varies alternately throughout the section. Based on the characteristic occurrences of major ebridian taxa, the ebridian assemblageswere divided into GroupsAtoDin stratigraphic order. The ebridian assemblages in piston core USGS Fl-422 from the Alpha Ridge probably correlate to our assemblage Group A of early middle Eocene age, although rare younger taxa are irregularly included.