The evolutionary history of the monotremes

The fossil record of Metasequoia Miki is extensive and demonstrates that the genus was widely distributed throughout North America and Eurasia from the early Late Cretaceous to the Plio-Pleistocene. The genus first appears in Cenomanian age deposits from western Canada, Alaska and the Arkagala and Koylma River basins in Russia and indicates that Metasequoia had achieved a wide distribution early in its evolutionary history. Exchange of Metasequoia between Asia and North America probably occurred across Beringia, which had become functional at the Albian-Cenomanian boundary (ca. 100 million years ago). However, if the inter-continental exchange of the early representatives of this genus occurred prior to the establishment of Beringia, migration would have still been possible across the Spitsbergen Corridor, which was functional during the Early Cretaceous. By the early Tertiary, the distribution patterns do not appear to have changed considerably from that seen during the Late Cretaceous, except that Metasequoia became a dominant constituent of the polar Broad-leaved Deciduous Forests. More importantly, the distribution of Metasequoia indicates that the genus grew and reproduced under a diverse range of climatic and environmental conditions throughout geologic time, including the cold and unique lighting conditions of the polar latitudes. Of particular interest is the apparent lack of Metasequoia fossils in Europe despite the presence of two land bridges linking North America and Europe throughout the early Tertiary and the drying of the Turgai Straits that separated eastern and western Asia up until Oligocene time. Metasequoia persisted in western Siberia and the Canadian Arctic until late Pliocene time, and in western Georgia and Japan until the late Pliocene-early Pleistocene. Following the apparent early Pleistocene extinction, Metasequoia re-appeared in southeastern China. The pronounced reduction in distribution during the Miocene appears to be coupled with increasing global aridity and cooling and increased competition for resources and habitat from representatives of the Pinaceae. With few exceptions, the bulk of the Metasequoia fossils described in the literature indicate that the fossils assigned to M. occidentalis are indistinguishable from the living species. The remarkable morphological stasis observed in Metasequoia demonstrates that the genus has remained unchanged, at least morphologically, since the early Late Cretaceous.

Relative to the numerous studies focused on mammalian schistosomes, fewer include avian schistosomatids particularly in the southern hemisphere. This is changing and current research emerging from the Neotropics shows a remarkable diversity of endemic taxa. To contribute to this effort, nine ducks (Spatula cyanoptera, S.versicolor, Netta peposaca), 12 swans (Cygnus melancoryphus) and 1,400 Physa spp. snails from Chile and Argentina were collected for adults and larval schistosomatids, respectively. Isolated schistosomatids were preserved for morphological and molecular analyses (28S and COI genes). Four different schistosomatid taxa were retrieved from birds: Trichobilharzia sp. in N. peposaca and S. cyanoptera that formed a clade; S.cyanoptera and S. versicolor hosted Trichobilharzia querquedulae; Cygnus melancoryphus hosted the nasal schistosomatid, Nasusbilharzia melancorhypha; and one visceral, Schistosomatidae gen. sp., which formed a clade with furcocercariae from Argentina and Chile from previous work. Of the physid snails, only one from Argentina had schistosomatid furcocercariae that based on molecular analyses grouped with T. querquedulae. This study represents the first description of adult schistosomatids from Chile as well as the elucidation of the life cycles of N.melancorhypha and T. querquedulae in Chile and Neotropics, respectively. Without well-preserved adults, the putative new genus Schistosomatidae gen. sp. could not be described, but its life cycle involves Chilina spp. and C. melancoryphus. Scanning electron microscopy of T. querquedulae revealed additional, undescribed morphological traits, highlighting its diagnostic importance. Authors stress the need for additional surveys of avian schistosomatids from the Neotropics to better understand their evolutionary history.

Cuttings recovered from two deep exploratory wells in the Lihue Basin, Kauai, Hawaii, include fossiliferous marine deposits that offer an uncommon opportunity to study paleoenvironments from the deep subsurface in Hawaii and interpret the paleogeography and geologic history of Kauai. These deposits indicate that two marine incursions gave rise to protected shallow-water, low-energy embayments in the southern part of the Lihue Basin in the late Pliocene–early Pleistocene. During the first marine incursion, the embayment was initially zoned, with a variable-salinity environment nearshore and a normal-marine reef environment offshore. The offshore reef environment eventually evolved to a nearshore, variable-salinity environment as the outer part of the embayment shallowed. During the second marine incursion, the embayment had normal-marine to hypersaline conditions, which constitute a significant departure from the variable-salinity environment present during the first marine incursion. Large streams draining the southern Lihue Basin are a likely source of the freshwater that caused the salinity fluctuations evident in the fossils from the first marine incursion. Subsequent volcanic eruptions produced lava flows that buried the embayment and probably diverted much of the stream flow in the southern Lihue Basin northward, to its present point of discharge north of Kalepa Ridge. As a result, the embayment that formed during the second marine incursion received less freshwater, and a normal-marine to hypersaline environment developed. The shallow-water marine deposits, currently buried between 86 m and 185 m below present sea level, have implications for regional tectonics and global eustasy.

GLACIATION, CAUSES | Milankovitch Theory and Paleoclimate

The fossil record of the puma lineage in America is sparse, and doubts have been raised about the origin, radiation, and migration events of this lineage. In this study, we present results of comparative and quantitative analyses on a complete left calcaneum, collected by Enrique de Carles at the beginning of the twentieth century. The calcaneum is relatively small-sized, slender-shaped, with a long and lateromedially compressed tubercle, calcaneal canal covered by a bridge that connects the ectal and sustentacular facets, sustentacular facet proximo-medially projected, quadratus plantae process reduced, groove for the flexor digitorum lateralis markedly delimited, and transversely oriented cuboidal facet. Comparative analysis, coupled with principle component analysis using linear measurements, allows us to confidently assign the fossil to the puma lineage. Given the preservation of a single autopodial element and its unique combination of features, we propose assigning the remain to gen. et sp. indet. The morphology of the element suggests cursorial adaptations, intermediate between living South American species and cheetahs. Despite uncertainty regarding exact stratigraphic provenance, the fossil studied represents the first carnivoran known for the Uquia Formation, and one of the earliest records of the puma lineage in America, and of Felidae in South America. These results highlight the already established high value of the Quebrada de Humahuaca for understanding the Great American Biotic Interchange and the need for future prospective campaigns in the region.

The Chalk aquifer of East Anglia is heavily exploited as a groundwater source. During exploration and exploitation, it has become clear that some of the groundwater in the Chalk is brackish and unsuitable for drinking (>250 mg l −1 chloride). Data comprising chemical analyses of pumped water samples and borehole depth samples (more than 900 results in total), and downhole geophysical surveys have been used to assemble maps of the distribution of chloride areally and with depth. Brackish or saline water is probably present at depth in the Chalk, even where shallow freshwater is present, over much of the area where Crag Group marine sediments have been deposited. The depth below surface at which brackish water is encountered varies between 50 and more than 100 m, and the elevation of the transition varies from below −91 to +16 m above ordnance datum (AOD). From its chemistry, it is deduced that most of the brackish water is of ancient marine origin but that there has been localized intrusion of modern seawater in coastal areas, especially around Ipswich. Saline water most probably entered the aquifer during Crag Group times (late Pliocene–early Pleistocene) and its chemistry has been modified subsequently. The most saline old water that has been encountered has full marine salinity.

High-frequency controls on alluvial successions: An integrated sedimentological and palaeopedological approach to the Plio-Pleistocene of Argentina

The Plio-Pleistocene sedimentary rocks of the Sorbas Basin, SE Spain are used to reconstruct the palaeogeography, palaeoclimate and active tectonics operative in the Late Pliocene–Early Pleistocene. The deposits are generated from two distinct source areas. These are (1) relatively larger catchments developed across a structural lineament situated in the foothills of the Sierra Alhamilla and (2) a more basinal, smaller catchment developed to the north of the structural lineament. The alluvial systems show evidence for sheet flooding, channelized flow, and overbank sedimentation in distal and marginal areas and are interpreted as fluvial distributary systems. The deposits were subjected to syn-sedimentary folding which exerted a strong control on the general topography at the time of alluvial system development. The balance between the accommodation space created by the tectonics operative over the Plio-Pleistocene, coupled with the sediment discharge, determined the alluvial system morphology and sedimentological architecture. The eventual cessation of deposition from the larger catchments is explained by their capture by an aggressive external drainage developing south of the structural lineament. The switching off of sediment supply from the larger catchments, coupled with high subsidence rates in the sediment dispersal area enabled the smaller alluvial system, still connected to its source area north of the lineament, to expand. Eventually the remaining catchment areas were also reduced by continued river capture. The study emphasizes the significance of river capture in re-routing both sediment and water discharge between sedimentary basins (the Sorbas Basin lost 15% of its original sediment and water budget to the Lucainena fan delta and associated coastal system of the Carboneras Basin to the south) and its subsequent effect on the pirated area (reduction in rates and changes in style of deposition). These latter factors outweighed the direct impact of tectonics and climate on the later development of the studied alluvial systems. The study emphasizes that to maximize the effects of sediment re-routing on actively aggrading alluvial systems (in the sedimentary basins) the positioning of the capture point is crucial and is most effective where (1) the sediment supply areas (mountain catchments) are pirated closest to their outlet (mountain front) into the receiving sedimentary basin and (2) the pirating drainages are external to the sedimentary basin.

Xenarthrans constitute a relict clade of endemic South American placental mammals with a long evolutionary history starting, at least, in the early Eocene. Within Xenarthra, Glyptodontidae (late Eocene–earliest Holocene) was a conspicuous group of large-sized armoured herbivores. During the Pleistocene (ca. 2.6–0.001 Ma) several genera (e.g. Panochthus and Glyptodon) achieved a remarkable latitudinal distribution in South America, as members of one of the xenarthran groups that participated in the Great American Biotic Interchange. Knowledge of the evolutionary history of this clade in some areas remains poorly known, especially in the high elevation Andean and sub-Andean regions of South America. Here we describe a new species, Glyptodon jatunkhirkhi sp. nov., from several localities of the Eastern Cordillera in Bolivia (ca. 2500–4100 m above sea level). From a phylogenetic viewpoint this new taxon appears as the sister group of the two lowland species recorded in southern South America (Glyptodon munizi + G. reticulatus), and this is congruent with the morphological differences observed between both clades, mainly with respect to the general morphology of the dorsal carapace and the skull. This new species expands the complex biogeographical scenario for Pleistocene glyptodonts and highlights the importance of Andean areas as key in understanding the evolutionary history of this clade. According to this revision, the diversity of Glyptodon is limited to G. munizi and G. reticulatus (two chronologically successive lowland species) plus this new species. The genera Panochthus (P. hipsilis) and Glyptodon seem to be the only Pleistocene glyptodonts to have been adapted to high elevation environments.http://zoobank.org/urn:lsid:zoobank.org:pub:7B5EFC11-626A-4BB5-8A00-DF657741698C

Cenozoic terrestrial mammals from Sardinia contribute substantial information for reconstructing the complex history of the western Mediterranean. The occurrence of endemic perissodactyls in Eocene marine and marsh deposits suggests the existence of ecological or physical barriers between the Corso-Sardinian massif and the Iberian-Occitanic area. At the end of the Oligocene, isolation of Sardinia was almost complete, although a migration from Europe occurred at the beginning of the Early Miocene, as indicated by the unbalanced endemic fauna from Oschiri. During the Late Miocene, the Tusco-Sardinian palaeobioprovince came into existence as an isolated region inhabited by the quite diversified, but notably endemic, Oreopithecus fauna. Sardinia was definitely isolated from Tuscany by the Messinian, but temporary connections with the European mainland possibly allowed the colonization of forerunners of some Sardinian Pliocene taxa. During the Plio-Pleistocene, Sardinia maintained permanent isolation. However, sea level drop, resulting in a relatively short distance between Sardinia and the European mainland, allowed different migratory events. From the Late Pliocene to the Late Pleistocene-Holocene, two main mammalian faunal complexes (FC) can be recognized: the Nesogoral FC (Late Pliocene-Early Pleistocene) and the Microtus (Tyrrhenicola) FC (late Early Pleistocene-Early Holocene). At the transition from Nesogoral to Microtus (Tyrrhenicola) FC, approximately 47% of the genera and 76% of the species disappeared, while approximately 58% of the genera and 71% of the species appeared. A noticeable turnover followed the arrival of Neolithic man and his accompanying fauna. Nonetheless, Praemegaceros was still present at about 7000 years BP, while Microtus (Tyrrhenicola) and Prolagus are respectively recorded in the Bronze and Iron Ages.

Aeolian dust, a primary terrigenous component of ocean sediments, has been widely used to reconstruct the paleoclimatic evolution because its transported distance, grain size and concentration are sensitive to climate changes. To further characterize the aeolian dust, the deposits at site Ocean Drilling Program (ODP) 882A in northwestern Pacific Ocean are divided into four grain-size fractions ( 64 μm) using the gravitative differentiation method. Detailed rock magnetism results show that magnetite and hematite are dominant magnetic minerals for the dust components. In addition, the aeolian dust ( 64 μm) contributes little to the magnetic enhancement of the sediments at 2.73 Ma. These new results greatly improve our understanding of paleoenvironmental evolution during late Pliocene-early Pleistocene in this area.

Based on comprehensive distributional records of the 23 species currently assigned to the lizard genus Tropidurus, we investigated patterns of endemism and area relationships in South America. Two biogeographic methods were applied, Parsimony Analysis of Endemicity (PAE) and Brooks Parsimony Analysis (BPA). Two areas of endemism were detected by PAE: the first within the domains of the semiarid Brazilian Caatinga, which includes seven endemic species, and the second in the region of the Serranía de Huanchaca, eastern Bolivia, in which three endemic species are present. The area cladograms recovered a close relationship between the Atlantic Forest and areas of the South American open corridor. The results revealed a close relationship among the provinces Caatinga (Cerrado, Parana Forest (Pantanal+Chaco)). The uplift of the Brazilian Central Plateau in the Late Pliocene-Early Pleistocene (4-2 Myr BP) has been interpreted as a major event responsible for isolation and differentiation of biotas along these areas. However, we emphasize that without the establishment of a temporal framework concerning the diversification history of Tropidurus it is premature to correlate cladogenetic events with specific time periods or putative vicariant scenarios. The limiting factors hampering the understanding of the biogeographic history of this genus include (1) the absence of temporal references in relation to the diversification of distinct clades within Tropidurus; (2) the lack of an appropriate taxonomic resolution of the species complexes currently represented by widely distributed forms; and (3) the need for a comprehensive phylogenetic hypothesis. We suggest that these three important aspects should be prioritized in future investigations.

The biogeographic dynamics affecting the Indian subcontinent, East and Southeast Asia during the Plio-Pleistocene has generated complex biodiversity patterns. We assessed the molecular biogeography of the small Indian civet (Viverricula indica) through mitogenome and cytochrome b + control region sequencing of 89 historical and modern samples to (1) establish a time-calibrated phylogeography across the species' native range and (2) test introduction scenarios to western Indian Ocean islands. Bayesian phylogenetic analyses identified 3 geographic lineages (East Asia, sister-group to Southeast Asia and the Indian subcontinent + northern Indochina) diverging 3.2-2.3 million years ago (Mya), with no clear signature of past demographic expansion. Within Southeast Asia, Balinese populations separated from the rest 2.6-1.3 Mya. Western Indian Ocean populations were assigned to the Indian subcontinent + northern Indochina lineage and had the lowest mitochondrial diversity. Approximate Bayesian computation did not distinguish between single versus multiple introduction scenarios. The early diversification of the small Indian civet was likely shaped by humid periods in the Late Pliocene-Early Pleistocene that created evergreen rainforest barriers, generating areas of intra-specific endemism in the Indian subcontinent, East, and Southeast Asia. Later, Pleistocene dispersals through drier conditions in South and Southeast Asia were likely, giving rise to the species' current natural distribution. Our molecular data supported the delineation of only 4 subspecies in V. indica, including an endemic Balinese lineage. Our study also highlighted the influence of prefirst millennium AD introductions to western Indian Ocean islands, with Indian and/or Arab traders probably introducing the species for its civet oil.

Tertiary climate and phytogeography in southeastern Australia

Neotectonically controlled fluvial features, Wałbrzych Upland, Middle Sudeten Mts, southwestern Poland