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Lower Paleocene marine siliciclastics of the Sobral Formation (Seymour Island, Antarctica) form an important component of a key southern high latitude reference section for the Maastrichtian–Eocene. The formation comprises a coarsening-upward, regressive succession (270 m thick), shallowing from prodeltaic, mud-rich to sandy nearshore sediments. Sedimentary facies analysis, integrated with macrofaunal and microfloral palaeoecological studies, indicate a wave-dominated, tidally influenced deltaic environment. Four depositional sequences (1–4) record the role of relative sea-level changes in controlling the stepwise progradation of the system. Prodeltaic and distal delta-front deposits (Sequences 1, 2), comprise coarsening-upward parasequences of mud-rich heteroliths and bioturbated fine-grained muddy sands displaying draped slump scars. The overlying erosional sequence boundary is marked by incised valleys filled with fluvio-estuarine sediments; succeeding sand-rich facies (Sequences 3, 4) represent the proximal delta front and delta platform. The macro-invertebrate and palynological datasets display contrasting responses to the regressive history of the formation. The macrofaunal record in the distal deltaic sediments reflects the marine influence, though a stratigraphic increase in diversity was controlled both by ecological factors and biotic recovery following the K–Pg event. The associated palynological assemblage also displays a strong marine signal and includes typical outer neritic – oceanic dinoflagellate cyst taxa. A sharp decline in macrofossil diversity and abundance in Sequences 3, 4 is compatible with ecological stress in shallow-water, restricted inshore settings. Though the palynological record at this level is terrestrially dominated, the marine component reflects the cosmopolitan nature of dinoflagellates, displaying the highest diversities in the formation. The regressive Sobral Formation ended a protracted c. 60 Myr history of regional subsidence

The late Palaeocene (Thanetian) Cross Valley Formation on Seymour Island is one of the few floras of this age in Antarctica. Understanding the diversity is critical for comparisons with coeval high-latitude forests and their evolution across South America and Australasia. This macroflora has few conifers and ferns but a significant diversity of angiosperms. Taxonomic assessment of previously undescribed morphotypes, based on new and existing collections, facilitated the identification of twelve new tooth-margined angiosperms of uncertain affinities. Comparisons to Gondwanan families already established in the Cross Valley Flora from pollen and wood records include Nothofagaceae, Proteaceae and Cunoniaceae. A total of 37 angiosperm taxa, including 23 tooth-margined and 14 entire-margined morphotypes, have been described from the Cross Valley Flora. They provide evidence that the most diverse Palaeocene floral assemblage recorded from this region inhabited the east side of the Antarctic Peninsula. The new morphotypes enrich the cool-temperate nature of the angiosperms that dominated over the conifers in these high-latitude forests. They indicate dynamic forests that responded to frequent disturbance as they grew on the slopes of active volcanoes; a physical divide that created a rainfall and climatic gradient from east to west across the Antarctic Peninsula. Floral elements, such as Proteaceae that indicates drier climates and Nothofagaceae that indicates cooler climates, signify that these forests were on the lee side of volcanoes on the Antarctic Peninsula. These forests represent extirpation and retraction of the Valdivian cool-temperate rainforests, which extended further south than their modern Patagonian distribution, in southern South America. Thus, the new morphotypes suggest additional floral diversity was present in the late Palaeocene and highlight the diversity contrast between the east and west Antarctic Peninsula.

Paleocene leaf floras are rare in high latitudes of the Southern Hemisphere, where studies have shown higher taxonomic diversity compared to Northern Hemisphere equivalents. The floras provide valuable insights into biodiversity and forest communities during the Paleocene. The Antarctic Peninsula hosts a wealth of Paleocene–Eocene floras which have been used to interpret climates before, during and after one of the most abrupt and transient warming events known from the geological record. The best-preserved and most diverse Paleocene macrofossils from this region come from the Cross Valley Formation, Seymour Island Group, which have previously provided evidence for warm temperate climates prior to the PETM. Here we present the taxonomy of leaf impressions from the Paleocene Cross Valley Flora for one species and ten new leaf morphotypes of entire-margined angiosperms. The new morphotypes provide evidence of an increased angiosperm diversity within cool-temperate Gondwanan forest inhabiting the east side of the Antarctic Peninsula, which contrasts with a lower floral diversity on the west side of the Peninsula during the late Paleocene.

Fossil-bearing deposits in the Transantarctic Mountains, Antarctica indicate that, despite the cold nature of the continent’s climate, a tundra ecosystem grew during periods of ice sheet retreat in the mid to late Neogene (17–2.5 Ma), 480 km from the South Pole. To date, palaeotemperature reconstruction has been based only on biological ranges, thereby calling for a geochemical approach to understanding continental climate and environment. There is contradictory evidence in the fossil record as to whether this flora was mixed angiosperm-conifer vegetation, or whether by this point conifers had disappeared from the continent. In order to address these questions, we have analysed, for the first time in sediments of this age, plant and bacterial biomarkers in terrestrial sediments from the Transantarctic Mountains to reconstruct past temperature and vegetation during a period of East Antarctic Ice Sheet retreat. From tetraether lipids (MBT’/CBT palaeothermometer), we conclude that the mean continental summer temperature was ca. 5 °C, in agreement with previous reconstructions. This was warm enough to have allowed woody vegetation to survive and reproduce even during the austral winter. Biomarkers from vascular plants indicate a low diversity and spatially variable flora consisting of higher plants, moss and algal mats growing in microenvironments in a glacial outwash system. Abietane-type compounds were abundant in some samples, indicating that conifers, most likely Podocarpaceae, grew on the Antarctic continent well into the Neogene. This is supported by the palynological record, but not the macrofossil record for the continent, and has implications for the evolution of vegetation on Antarctica.

Two stratigraphically closely spaced bedding planes exposed at Lamping Peak in the Upper Buckley Formation, Beardmore Glacier area, Antarctica contain abundant in situ stumps (n=53, n=21) and other plant fossils that allow reconstruction of forest structure and biomass of Glossopteris forests that thrived at ~ 75o S paleolatitude in the Permian. Mean trunk diameter is 14 and 25 cm, corresponding to estimated mean maximum heights of 12 and 19 m. Basal areas are 65 and 80 m2ha- 1. The above ground biomass was calculated using allometric equations for Ginkgo biloba, yielding biomasses of 147 and 178 Mg ha- 1. Biomass estimates based on comparison with biomass of modern forests with equivalent basal areas are higher (225 – 400 Mg ha- 1). The amount of above ground biomass added each year (Annual Net Primary Productivity), based on biomass estimates and growth rings in silicified plant material from the Buckley Formation nearby, is poorly constrained, ranging from ~ 100 – 2000 g m- 2 yr- 1. Compared to modern forests at all latitudes, the Permian forests have high basal areas and high biomass, exceeded in both only by forests of the U.S. Pacific northwest and Sequoia forests. The estimated range of productivity (ANPP) is within that of many very productive modern forests. The Lamping Peak forests’ basal areas and calculated biomass are also larger than younger high paleolatitude fossil forests except for Arctic Cenozoic forests. Presence of these highly productive fossil forests at high paleolatitude is consistent with hothouse conditions during the Late Permian, prior to the eruption of the Siberian flood basalts.

A late Oligocene plant macrofossil assemblage is described from the Río Leona Formation, Argentinian Patagonia. This includes a fern, “Blechnum turbioensis” Frenguelli, one species of conifer, and sixteen angiosperm taxa. Rosaceae, Myrtaceae, Proteaceae, Lauraceae, Anacardiaceae and Typhaceae are represented by one species in each family. Five species are considered to be members of the Fabales. Three leaf taxa together with Carpolithus seeds are placed in the Nothofagaceae. Palynomorphs and permineralized woods complete the floral record of the Río Leona Formation, which is considered early late Oligocene based on radiometric dating and palynofloras.

One of the most expanded records to contain the final fortunes of ammonoid cephalopods is within the López de Bertodano Formation of Seymour Island, James Ross Basin, Antarctica. Located at ~ 65° South now, and during the Cretaceous, this sequence is the highest southern latitude onshore outcrop containing the Cretaceous-Paleogene (K–Pg) transition. We present comprehensive new biostratigraphic range data for 14 ammonite and one nautiloid species based on the collection of > 700 macrofossils from high-resolution sampling of parallel sedimentary sections, dated Maastrichtian to earliest Danian in age, across southern Seymour Island. We find evidence for only a single, abrupt pulse of cephalopod extinction at the end of the Cretaceous when the final seven ammonite species disappeared, consistent with most evidence globally. In the lead up to the K–Pg extinction in the James Ross Basin, starting during the Campanian, ammonite diversity decreased overall, but the number of endemic taxa belonging to the family Kossmaticeratidae actually increased. This pattern continued into the Maastrichtian and may be facies controlled, linked to changes in sea level and seawater temperature. During the early Maastrichtian, ammonite diversity dropped significantly with only two species recorded from the basal López de Bertodano Formation on Seymour Island. The subsequent diversification of endemic taxa and reappearance of long-ranging, widespread species into the basin resulted in an increase in ammonite diversity and abundance during the mid-Maastrichtian. This was coincident with an apparent period of warming temperatures and sea level rise interpreted from palynology and sedimentology, perhaps reflecting a high latitude expression of the Mid-Maastrichtian Event. Late Maastrichtian diversity levels remained stable despite reported climatic and environmental variation. Ammonite diversity patterns during the Maastrichtian parallel those of microfossil species such as nannofossil and pl

Fluctuations in Late Cretaceous climate were already influencing biotic change prior to the environmental upheaval at the Cretaceous – Paleogene (K–Pg) boundary, but their general nature, magnitude and timing remain controversial. A high-resolution dataset on terrestrially-derived palynomorphs is presented from the high southern palaeolatitudes that unlocks details of small-scale climate variability throughout this period of significant global change. Specifically, this is a quantitative spore and pollen analysis of an expanded uppermost Cretaceous to lowermost Paleogene (Maastrichtian – earliest Danian) shallow marine sedimentary succession from Seymour Island, off the northeastern tip of the Antarctic Peninsula, then (as now) located at ~ 65°S. Using nearest living relatives the first detailed vegetation, habitat and climate reconstruction is presented for the emergent volcanic arc at this time. On the coastal lowlands, a cool to warm temperate rainforest is envisaged growing in a riverine landscape, with both wet (river margin, pond) and relatively dry (interfluve, canopy gap) habitats. Diverse podocarps and southern beech trees grew alongside angiosperm herbs and shrubs in mean annual temperatures of ~ 10 – 15°C. Higher altitude araucarian forests gave way to open ericaceous heathland, beyond the tree line, in subalpine to alpine conditions with mean annual temperatures of a cold ~ 5 – 8°C. There is no exact modern botanical equivalent, but the closest modern flora is that of the Andes of southern Chile and Argentina. Maastrichtian climate is shown to have fluctuated from cool, humid conditions, through a rapid warming ~ 2 million years prior to the K–Pg transition, followed by cooling during the earliest Danian, a trend supported by previous work on this interval.

The thickest uppermost Cretaceous to lowermost Paleogene (Maastrichtian to Danian) sedimentary succession in the world is exposed on southern Seymour Island (65° South) in the James Ross Basin, Antarctic Peninsula. This fossiliferous shallow marine sequence, which spans the Cretaceous–Paleogene boundary, has allowed a high-resolution analysis of well-preserved marine palynomorphs. Previous correlation of Cretaceous–Paleogene marine palynomorph assemblages in the south polar region relied on dinoflagellate cyst biozonations from New Zealand and southern Australia. The age model of the southern Seymour Island succession is refined and placed within the stratigraphical context of the mid to high southern palaeolatitudes. Quantitative palynological analysis of a new 1102 m continuous stratigraphical section comprising the uppermost Snow Hill Island Formation and the López de Bertodano Formation (Marambio Group) across southern Seymour Island was undertaken. We propose the first formal late Maastrichtian to early Danian dinoflagellate cyst zonation scheme for the Antarctic based on this exceptional succession. Two new late Maastrichtian zones, including three subzones, and one new early Danian zone are defined. The oldest beds correlate well with the late Maastrichtian of New Zealand. In a wider context, a new South Polar Province based on Maastrichtian to Danian dinoflagellate cysts is proposed, which excludes most southern South American marine palynofloras. This interpretation is supported by models of ocean currents around Antarctica and implies an unrestricted oceanic connection across Antarctica between southern South America and the Tasman Sea.

Fossil wood of the Atherospermataceae from the upper Cretaceous of James Ross Island, Antarctica, is described for the first time and represents the earliest record of this family in the Southern Hemisphere. The specimens are characterised by diffuse porous arrangement of vessels, scalariform perforation plates, scalariform and opposite intervessel pitting and predominantly multiseriate rays which occasionally bear low, uniseriate margins. Despite anatomical conformity at the familial level, the fossil woods are not identical to any one extant genus and have therefore been assigned to the fossil organ genus, Laurelites Nishida, Nishida et Nasa, with which the fossils show greatest similarity.