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The Cretaceous period is particularly well represented by a thick sequence of clastic sedimentary rocks exposed in the Antarctic Peninsula region of western Antarctica. This was an active margin throughout the Late Mesozoic and in total some 7km+ of Cretaceous sedimentary rocks accumulated in a series of fore-, intra-, and back-arc basins. The Fossil Bluff Group of eastern Alexander Island can be traced from the Jurassic - Cretaceous boundary into the Upper Albian and represents a broad-scale shallowing-upwards sequence from deep marine to a prominent Upper Albian fluvial interval in which high density forests developed at a palaeolatitude of 75°S. The Cretaceous sequence exposed in the James Ross Island group continues right through the Upper Cretaceous to the K–Pg boundary. The Campanian - Maastrichtian succession in particular is over 2km in total thickness and richly fossiliferous. The improved Cretaceous stratigraphy of Antarctica is an invaluable terrestrial record of climatic change at a high palaeolatitude. This includes a gradual increase in temperature to the Cretaceous Thermal Maximum, and then a decline to the K–Pg boundary. There may be no simple link between these palaeotemperature changes and Cretaceous patterns of biotic radiation and extinction.

The mid-Cretaceous period was one of the warmest intervals of the past 140 million years, driven by atmospheric carbon dioxide levels of around 1,000 parts per million by volume. In the near absence of proximal geological records from south of the Antarctic Circle, it is disputed whether polar ice could exist under such environmental conditions. Here we use a sedimentary sequence recovered from the West Antarctic shelf—the southernmost Cretaceous record reported so far—and show that a temperate lowland rainforest environment existed at a palaeolatitude of about 82° S during the Turonian–Santonian age (92 to 83 million years ago). This record contains an intact 3-metre-long network of in situ fossil roots embedded in a mudstone matrix containing diverse pollen and spores. A climate model simulation shows that the reconstructed temperate climate at this high latitude requires a combination of both atmospheric carbon dioxide concentrations of 1,120–1,680 parts per million by volume and a vegetated land surface without major Antarctic glaciation, highlighting the important cooling effect exerted by ice albedo under high levels of atmospheric carbon dioxide.

The mid-Cretaceous period was one of the warmest intervals of the past 140 million years1,2,3,4,5, driven by atmospheric carbon dioxide levels of around 1,000 parts per million by volume6. In the near absence of proximal geological records from south of the Antarctic Circle, it is disputed whether polar ice could exist under such environmental conditions. Here we use a sedimentary sequence recovered from the West Antarctic shelf—the southernmost Cretaceous record reported so far—and show that a temperate lowland rainforest environment existed at a palaeolatitude of about 82° S during the Turonian–Santonian age (92 to 83 million years ago). This record contains an intact 3-metre-long network of in situ fossil roots embedded in a mudstone matrix containing diverse pollen and spores. A climate model simulation shows that the reconstructed temperate climate at this high latitude requires a combination of both atmospheric carbon dioxide concentrations of 1,120–1,680 parts per million by volume and a vegetated land surface without major Antarctic glaciation, highlighting the important cooling effect exerted by ice albedo under high levels of atmospheric carbon dioxide.

Climate plays a significant role in determining the styles of depositional processes at different latitudes, which in turn influence the locations of hydrocarbon systems. Results of climate modeling may therefore provide important information for predicting the presence or absence of suitable hydrocarbon plays. To determine whether the models provide realistic results, the critical step is to validate the model results against proxy data where they are available. Paleoclimate proxy data are most often derived from more accessible low- to midlatitude regions and are biased towards warm climate states. However, general circulation models (GCMs) have traditionally been biased to colder temperatures, in particular at high-latitudes, struggling to maintain the high-latitude regions warm enough to sustain forests that were present during greenhouse periods, such as the mid-Cretaceous (~130–89 Ma), without exaggerated warming of the equatorial regions. To improve this approach, the HadCM3L coupled atmosphere–ocean GCM, a state-of-the-art model for the long simulations required to reach an equilibrium climate, was run for each stage of the Cretaceous using new paleogeographic base maps. Here, we compare the results for the Aptian (118.5 Ma) and Albian (105.8 Ma) with paleoclimate proxy data from the high northern latitudes in order to determine if the model produces viable results for this region. Paleoclimate analysis of fossil wood from conifer forests from Svalbard of Aptian–Albian age suggests that they grew in moist cool upland areas adjacent to warmer temperate lowland regions, probably with rivers and/or swamps present. Studies of conifers from the Canadian Arctic islands indicate that they grew under slightly cooler conditions than on Svalbard, similar to northern Canada today. The HadCM3L GCM results for Svalbard show that the dominant biome was evergreen taiga/montane forest with lowland temperate vegetation present during the Albian Stage, possibly with an elemen

The mid-Cretaceous was one of the warmest intervals of the past 140 million years (Myr) driven by atmospheric CO2 levels around 1000 ppmv. In the near absence of proximal geological records from south of the Antarctic Circle, it remains disputed whether polar ice could exist under such environmental conditions. Here we present results from a unique sedimentary sequence recovered from the West Antarctic shelf. This by far southernmost Cretaceous record contains an intact ~3 m-long network of in-situ fossil roots. The roots are embedded in a mudstone matrix bearing diverse pollen and spores, indicative of a temperate lowland rainforest environment at a palaeolatitude of ~82°S during the Turonian–Santonian (92–83 Myr). A climate model simulation shows that the reconstructed temperate climate at this high latitude requires a combination of both atmospheric CO2 contents of 1120–1680 ppmv and a vegetated land surface without major Antarctic glaciation, highlighting the important cooling effect exerted by ice albedo in high-CO2 climate worlds.

Taxonomic and ecological recovery from the Cretaceous–Palaeogene (K–Pg) mass extinction 66 million years ago shaped the composition and structure of modern ecosystems. The timing and nature of recovery has been linked to many factors including palaeolatitude, geographical range, the ecology of survivors, incumbency and palaeoenvironmental setting. Using a temporally constrained fossil dataset from one of the most expanded K–Pg successions in the world, integrated with palaeoenvironmental information, we provide the most detailed examination of the patterns and timing of recovery from the K–Pg mass extinction event in the high southern latitudes of Antarctica. The timing of biotic recovery was influenced by global stabilization of the wider Earth system following severe environmental perturbations, apparently regardless of latitude or local environment. Extinction intensity and ecological change were decoupled, with community scale ecological change less distinct compared to other locations, even if the taxonomic severity of the extinction was the same as at lower latitudes. This is consistent with a degree of geographical heterogeneity in the recovery from the K–Pg mass extinction. Recovery in Antarctica was influenced by local factors (such as water depth changes, local volcanism, and possibly incumbency and pre‐adaptation to seasonality of the local benthic molluscan population), and also showed global signals, for example the radiation of the Neogastropoda within the first million years of the Danian, and a shift in dominance between bivalves and gastropods.