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The Cenomanian–Turonian is considered the warmest interval of the last 150 million years. It was characterized by major disturbances to the global carbon cycle, resulting in elevated pCO 2 levels and global temperatures, and witnessed the rise to dominance of angiosperms floras. In this paper, we assess changes of fossil floras during the Cenomanian–Turonian interval based on palynological studies of two distantly-spaced localities in high southern paleolatitudes: the Mata Amarilla Formation of Patagonia, southern South America and the Tupuangi Formation of the Chatham Islands, New Zealand. Richness estimations for each stratigraphic unit and cluster analysis were conducted to assess the vegetation changes. Palynological dominance and the presence/absence of taxa were compiled for these units and compared with others from the Cenomanian of southern Gondwana. We recognize a peak in richness during the Mid-Cenomanian Event in Patagonia, with a fall in richness after the event due to species being displaced by dominant taxa. Several richness peaks are also recognized in New Zealand, but the lack of stratigraphic control prevents correlation with marine-based events. Oceanic Anoxic Event 2 is not recorded in either study area. The inclusion of Gondwanic palynological records demonstrate that the Tupuangi Formation cluster with sites from the Antarctic Peninsula and south-eastern Australia conforming a 'polar cluster'. However, this area has its own palynological signature, constituting a newly proposed Taxodiaceaepollenites Subprovince. The abundances of key plant groups of the Mata Amarilla Formation cluster with those of Bathurst Island (northern Australia), but also show important differences, likely owing to their geographic separation and latitudinal difference. In summary, our paper presents a new scheme for the mid-Cretaceous palynological provinces of Southern Gondwana and provides novel data sets for Patagonia and New Zealand, which can be used as reference points for palynological and paleoecological studies of coeval floras worldwide. • A peak of richness is described for the mid-Cenomanian Event in Patagonia. • After the mid-Cenomanian Event Patagonian palynofloras show a decrease in richness. • Five richness peaks are described for the Cenomanian–Turonian of New Zealand. • The Taxodiaceaepollenites Subprovince is proposed for New Zealand palynofloras. • Angiosperms are small portion of Gondwana palynofloras during Cenomanian–Turonian. [ABSTRACT FROM AUTHOR]

Factors affecting cetacean preservation and distribution in ancient sedimentary successions are not well understood. Actualistic studies have focused on coastal and deep marine examples, and little is known about taphonomic processes occurring within shelf environments. In this paper, we integrate sedimentological, taphonomic and palaeontological data for the cetacean-bearing lower Miocene Gaiman Formation from Patagonia, Argentina, to analyse which factors affected the distribution and preservation of cetaceans in several localities of the Southwestern Atlantic. Facies analysis shows that the formation represents a transgressive-regressive stratigraphic cycle, with palaeoenvironments including coastal, storm-dominated shoreface, inner shelf embayment and open inner shelf. Cetacean remains show preservation styles varying from isolated elements to articulated specimens, with nearly all remains restricted to both embayment and open marine inner shelf settings. Two fossil cetacean assemblages are recognized: Assemblage A comprises small-sized odontocetes dominated by Platanistoidea, preserved mostly in inner shelf embayment deposits; and Assemblage B comprises large-sized odontocetes and mysticetes, dominated by Physeteroidea and Balaenopteroidea, preserved mostly in open inner shelf deposits. Cetacean preservation style is controlled by a combination of palaeoenvironmental conditions, such as energy and sedimentation rate, and by biological factors, such as cetacean body plan and its impact on carcass buoyancy. Ecological factors may also explain the stratigraphic distribution of cetaceans between coastal and oceanic assemblages. This novel integrative and multidisciplinary analyses improves our knowledge of cetacean taphonomy in shelf environments. • Four coastal and shelf marine facies are identified for the lower Miocene Gaiman Formation of Argentina. • Cetaceans are mostly recorded in inner shelf deposits. • Cetacean preservation style is controlled by environmental and biological factors. • Cetaceans distribution is mostly controlled by palaeoecological factors. [ABSTRACT FROM AUTHOR]

Abstract: Lower Cretaceous trackways assignable to xiphosurids were recently found in tidally influenced marginal-marine deposits of the Agrio Formation (Patagonia, Argentina). The aim of this paper is to describe these trace fossils in detail, discuss their conditions of preservation, make palaeoecological and taphonomic inferences from them, and analyse the importance of their palaeogeographic location. These trace fossils are assigned to Kouphichnium, and five track morphotypes are established. Microbially induced sedimentary structures (MISS) are associated with the trackways. Scanning electron microscope (SEM) studies document the involvement of microbial mats in the preservation of the trackways by the presence of cyanobacteria-like filament sheaths. The microbial mats enabled preservation of the tracks by binding and biostabilisation of the sediment surface. The mostly likely producers of the trackways are from the subfamily Limulinae. The studied surface could represent a high-tide mating ground associated with a very shallow water deposit on a warm Cretaceous tidal flat. These records are the first convincingly documented trackways produced by xiphosurids in the Early Cretaceous worldwide and the second fossil record of this group from the Cretaceous in the Southern Hemisphere. [Copyright &y& Elsevier]

Abstract: Argentina is a special place to study Late Palaeozoic life and environmental change because of the excellent exposures of Late Palaeozoic sedimentary sequences. In particular, Patagonia has an almost continuous Late Palaeozoic succession containing well-preserved faunal assemblages characterized by both strong endemism and distinctive palaeobiogeographic links to Australia and northeast Asia. In this contribution an overview of the current knowledge of the invertebrate faunas of Patagonia and their biostratigraphic and palaeobiogeographic significance are presented, along with comments on the future prospects of research in the light of new findings. The Late Palaeozoic outcrops in central-western Patagonia belong to the Tepuel–Genoa Basin (Chubut province, Argentina), then located in southwestern Gondwana during the Late Palaezoic. In this basin the succession is >6000m thick, and constitutes a continuous and complete succession from the Lower Carboniferous to lower Permian. As such, it has the potential to serve as an important reference section for regional and intercontinental correlations. The marine Late Palaeozoic of Patagonia has yielded abundant and well-preserved representatives of most invertebrate groups: brachiopods, bivalves, gastropods, cephalopods, hyolithids, pelmatozoans, ostracods and cnidarians. Recently, studies of the Patagonian faunas have resulted in different opinions on the ages of the faunas. Biostratigraphic correlation is complex due to strong faunal provincialism. For this reason, there are several hypotheses concerning the biostratigraphic zonation in the basin. Since 1920, when studies of Late Palaeozoic strata in Patagonia were first carried out, numerous papers on stratigraphic, palaeogeographic and taxonomic subjects have been published, but our knowledge of Carboniferous–Permian fossils from the Tepuel–Genoa Basin is still incomplete. At present, we are attempting to integrate and calibrate the different faunal associations with a view to achieving a unified biostratigraphic biozonation scheme and hence a much improved understanding of the palaeobiogeographic relationship of Patagonian faunas with those from western Argentina and other continents. Currently, detailed stratigraphic and palaeontological research is being done in the type section of the Tepuel–Genoa Basin. The aim of our studies is to integrate all partial sequences exposed throughout the basin and to propose a biostratigraphic chart based on key invertebrate taxa. Once this goal is achieved, a global correlation can be conducted, especially with other sections in Gondwana and the Arctic. [Copyright &y& Elsevier]

Abstract: This paper presents an updated, extensive review of glacier fluctuations during the past 1000years in the extratropical Andes of South America between ca. 17° and 55°S. Given the variety of environmental conditions and evidence available for glacier fluctuations across this wide latitudinal range, regional accounts are given for the Desert Andes (∼17°–31°S), the Andes of central Chile and Argentina (31°–36°S), and the North (36°–45°S) and South (45°–55°S) Patagonian Andes. The techniques, dating limitations, and interpretations of the glacier records along this transect are also discussed. Information on glacier fluctuations in the Desert Andes is limited to the 20th century. Documentation on past glacier variations is more abundant in the Central Chilean-Argentinean Andes, but the number of chronologies dealing with glacier fluctuations prior to the 1900s is also limited. Most records indicate that glaciers were generally more extensive prior to the 20th century, with dates of maximum expansion ranging from the 16th to the 19th centuries. The number and extent of glaciers increase significantly in the Patagonian region, where the evidence available for dating glacier variations during the past centuries is more abundant and the dating control for glacier events is generally better than in the northern parts of the study area. For some Patagonian glaciers, maximum Little Ice Age (LIA) or post-LIA advances have been precisely dated by dendro-geomorphological determinations or in situ measurements. However, for most sites, the evidence available is still preliminary and there is considerable variability in the extent and timing of events related to the maximum LIA expansion identified in most areas between the 16th and 19th centuries. Evidence is starting to appear at a growing number of sites for glacier advances during the first half of the past millennium. These events were generally less extensive than the LIA maximum pulses. Despite the occurrence of several post-LIA readvances over the past 100–110years, most areas in the Andes of extratropical South America have experienced a general pattern of glacier recession and significant ice mass losses. The differences in the glacier histories observed at local and regional scales probably reflect the inherent limitations associated with the glacier records and/or the dating techniques used in each case together with the varying dominance of precipitation, temperature and other climatic and non-climatic factors on glacier mass balance and glacier dynamics. These differences indicate that the late Holocene glacier history of southern South America is more complex than commonly assumed. The evidence discussed in this study highlights not only the immense potential for glaciological studies of this region but also a significant need for an increased number of detailed, well-dated records of glacier fluctuations. [Copyright &y& Elsevier]

Resolving the history of vegetation, fire, and glaciation on the eastern slope of the central Patagonian Andes (44°-49°S) since the Last Glacial Termination (T1) has proved difficult. This is due to the steep environmental gradients, vegetation heterogeneity, and scarcity of dated glacial deposits and geomorphic features. Unsurprisingly, published records show important heterogeneities which limit our understanding of the timing and magnitude of climate and vegetation changes, and their driving mechanisms since T1. In this paper, we describe sediment cores from small closed-basin lakes located in the deciduous Nothofagus forest zone near Coyhaique, Chile. Our results indicate that the Coyhaique glacier lobe abandoned its final Last Glacial Maximum position just before ~17.9 cal kyr BP and underwent a step-wise recession that included a halt/readvance that culminated at ~16.8 cal kyr BP, contemporaneous with the formation of an ice-dammed proglacial lake in the Coyhaique/Balmaceda sector. This glacial lake stood at its highest level between ~17.9–17.2 cal kyr BP (<726 and > 650 m.a.s.l.), lowered between ~17.2–16.2 cal kyr BP (<650 and > 570 m.a.s.l.), and disappeared thereafter. Herbs and shrubs, currently dominant in high Andean and Patagonian steppe environments, colonized the ice-free terrains distal to the glacier margins and proglacial lakes under cold and dry conditions. This was followed by a steady increase in Nothofagus between ~16.6–14.8 cal kyr BP that led to the establishment of forests starting at ~14.8 cal kyr BP. The Holocene started with a sudden increase in Nothofagus and disappearance of conifers in the context of increase fire activity between ~11.7–9.4 cal kyr BP. Closed-canopy Nothofagus forests persisted virtually unaltered from ~9.4 cal kyr BP to the present day, despite frequent explosive volcanism and millennial-scale variations in fire regimes, attesting to their extraordinary postglacial resilience which contrasts with their behavior during T1. Recent large-scale deforestation by fire, livestock grazing, and the spread of non-native invasive plant species drove the fastest and largest-magnitude shifts seen during the last ~16,500 years. • Glacial retreat began at ~17.9 ka and followed a stepwise pattern until ~16.2 ka. • Arboreal Pollen rose at ~16.6 ka driven by stronger Southern Westerly Winds (SWW). • Rainforest conifers peaked between ~14.8–11.7 ka suggesting maximum SWW influence. • Fires and disappearance of conifers suggest weak SWW between ~11.7–9.4 ka. • Extraordinarily resilient Nothofagus forests have persisted since ~9.4 ka. [ABSTRACT FROM AUTHOR]

Marine sedimentary rocks of the lower Miocene Monte León Formation of southeastern Patagonia (Austral Basin), Argentina are important geological archives for better understanding regional tectonics, paleoenvironments, oceanography, and climate. In this paper, we describe assemblages of invertebrates, palynomorphs, foraminifera, ostracods and calcareous nannofossils in a stratigraphical and sedimentological framework, which suggest deposition during a transgressive-regressive cycle. From base to top, the lowermost outcropping deposits of the Punta Entrada Member represent an inner shelf environment, formed during a transgressive phase. The zone of maximum flooding is marked by a high diversity of protoperidiniaceans (heterotrophic) and offshore dinoflagellate cysts, an increase in the percentage and size of planktonic foraminifera, and a decrease in shallow water benthic foraminifera. Regressive deposits in the upper part of the Punta Entrada Member exhibit a progradational stratal stacking pattern and are characterized by an upward decrease in bioturbation and in the content of marine invertebrates; the dinoflagellate cyst assemblages point toward shallower and more restricted marine conditions than in underlying deposits. The cycle ends with the Monte Observación Member, which contains an impoverished and mostly reworked fauna of invertebrates. The presence of monospecific reefs of Crassostrea orbignyi , the decrease in dinoflagellate cysts and calcareous microfossils diversity, and the increase of continental palynomorphs suggest progressively shallower conditions and increasing influence of freshwater discharge. Although eustatic controls could have contributed to the sedimentary evolution of the Monte León Formation, the upward regressive trend is interpreted as the result of tectonism linked to the Andean orogeny, which led to the uplift, exhumation, and erosion of the highlands in the west. This is supported by the abundance of pyroclastic material, together with reworked specimens of Upper Cretaceous forams and Upper Cretaceous and middle Eocene dinoflagellate cysts in the upper part of the Punta Entrada Member and in the Monte Observación Member. • Multiproxy data indicate that study rocks represent a transgressive-regressive cycle. • A maximum flooding and/or higher organic flux zone was identified at the coastal cliffs. • The regressive trend was the result of tectonics, sediment supply dynamics, and volcanism. • Cretaceous/Eocene forams and dinocysts evidence exhumation and reworking from the Andes. [ABSTRACT FROM AUTHOR]

This paper analyzes the distribution patterns of pollen and spore assemblages in modern surface sediments recovered from the bottom of the San Jorge Gulf (SJG) and from offshore sites, in relation to the location of different phytogeographic provinces surrounding the SJG, including the distant forest from southwestern Patagonia. Results reveal that pollen spectra are dominated by Chenopodiaceae-Amaranthaceae, Poaceae, Asteraceae subf. Asteroideae, Colliguaja integerrima and Ephedra sp.; which represents the vegetation adjacent to the SJG. Overall, the pollen distribution in surface sediments reflects the location of the different phytogeographic provinces and will be used as modern-analogues to document vegetation history around the SJG. Pollen assemblages also reveal the latitudinal variation of vegetation taxa in the Patagonian steppe, which is characterized by a slight increase in herbaceous pollen and a decrease in high shrubs (e.g. Colliguaja integerrima) towards the southern-central part of the SJG. Furthermore, we identified two pollen taxa from the southwestern Patagonian forest, Nothofagus and Podocarpus that could be used as indicators of past dynamics and variations of the Southern Westerly Wind Belt (SWWB) in the SJG during the Late Pleistocene and Holocene. High pollen concentrations are recorded at the central part of the SJG (480–8080 grains/g), while low concentrations are measured in the northern and southern parts of the Gulf, as well as at offshore sites (26–1806 grains/g). The pollen distribution in the study area is most likely governed by the SWWB in combination with the marine sediment composition and surface currents flowing through the SJG. • Pollen and spore surface distribution patterns from the San Jorge Gulf. • Pollen assemblages echo different phytogeographic provinces surrounding the gulf. • Nothofagus and Podocarpus reflect long distance transport by westerly winds. • Pollen distribution results from transport by westerly winds and surface currents. [ABSTRACT FROM AUTHOR]

The lower Miocene Santa Cruz Formation (dated to ~18–16 Ma) of Southern Patagonia, Argentina, preserves rich vertebrate faunas, which are representative of communities that existed prior to the Great American Biotic Interchange (GABI). Some previous researchers have hypothesized that these pre-GABI faunas had a low richness of mammalian carnivores (an impoverished predator guild), while others argue for a predator/prey ratio similar to those of recent communities. In this paper, we analyze faunas from the lower part of the Santa Cruz Formation (FL 1–7) using a methodology that allows us to quantify (i) the meat resources that were available to the secondary consumers of the palaeocommunity; and (ii) the competition intensity for these resources. In our modeling, we considered different scenarios related to meat consumption, including the possibility that several taxa had a scavenging behavior, and also differences in mortality rates between young and adult prey. Our results provide estimates of the nutritional requirements from the predator/scavenger guild under maximum and minimum quantities of meat offered by the prey community, which indicate the presence of a well-balanced palaeocommunity. Moreover, the competition indices point to a relatively high level of competition for prey of small-to-medium size, although competition for resources from large mammal prey was rather low. This suggests that the predator/scavenger guild was not impoverished, although there were insufficient carnivore species to fully consume the megaherbivore biomass. • We analyze predator richness of mammalian communities that preceded the Great American Biotic Interchange in Patagonia. • The biomass supplied and required is quantified for palaeocommunites in the Miocene (Burdigalian) Santa Cruz Formation. • The biomass demanded by carnivores falls within the range of biomass available. • Competition intensity was high for small mammalian prey, but low for large ones. • Predator richness was well-balanced in this palaeocommunity, except for large prey. [ABSTRACT FROM AUTHOR]