Late Early Pliocene Research Articles

Neogene–Quaternary paleoenvironments and kerogen assessment of the NDO B-1 well, offshore Nile Delta, Egypt, Eastern Mediterranean: palynological evidence

Palynofacies and palynological investigations conducted on the Neogene–Quaternary succession from the NDO B-1 well, located in the offshore Nile Delta, Egypt, in the Eastern Mediterranean, suggest generally shallow marine (neritic) conditions. These environments are manifested by the overall palynofacies composition and the occurrence of dinoflagellate cysts (e.g., Spiniferites spp., Lingulodinium spp., Hystrichokolpoma spp., Homotryblium spp. and Selenopemphix spp.). Neritic environments are suggested for the lower and middle Miocene Sidi Salim, and the Pliocene to Pleistocene upper Kafr El Sheikh, El Wastani and Mit Ghamr formations, while shallower, coastal to inner neritic settings were interpreted for the late Miocene (Qawasim and Rosetta formations) and early Pliocene (Abu Madi and lower Kafr El Sheikh formations). Anoxic conditions existed during the deposition of the studied well succession, which can be seen from the occurrence of imprints of pyrite crystals and some types of oxygen-sensitive dinoflagellate cysts. The palynofacies fluctuated repeatedly between Amorphous Organic Matter (AOM)-dominated and phytoclast-dominated intervals, of kerogen types II and III, respectively. The spore coloration index (SCI) of indigenous thin-walled palynomorphs confirms thermally mature sediments, generative of dry gas and wet gas/condensates. Reworking during the deposition of the upper Sidi Salim, Qawasim and Rosetta formations is inferred from the occurrence of Cretaceous dinoflagellate cysts and pollen.

Distinct seasonal changes and precession forcing of surface and subsurface temperatures in the mid-latitudinal North Atlantic during the onset of the Late Pliocene

Abstract. The Late Pliocene marks the intensification of Northern Hemisphere glaciation (iNHG), offering a unique opportunity to study climate evolution and ice-sheet-related feedback mechanisms. In this study, we present high-resolution Mg / Ca-based sea surface temperatures (SSTs) and subsurface temperatures (SubTs) derived from the foraminiferal species Globigerinoides ruber and Globorotalia hirsuta, respectively, at the Integrated Ocean Drilling Program (IODP) Expedition 306 Site U1313 in the mid-latitudinal North Atlantic during the early Late Pliocene, 3.65–3.37 million years ago (Ma). We find distinct differences between our new G. ruber Mg / Ca-based SST record and previously published alkenone-based SST records from the same location. These discrepancies in both absolute values and variations highlight distinctly different seasonal influences on the proxies. The G. ruber Mg / Ca-based SST data were primarily influenced by local summer insolation, showing a dominant precession cycle. Conversely, the variations in alkenone-based SST, dominated by the obliquity and lacking the precession cycle, are found to be more indicative of cold-season changes, despite previous interpretations of these records as reflecting annual mean temperatures. A simultaneous decline in Mg / Ca-based SST and SubT records from 3.65 to 3.5 Ma suggests a diminished poleward oceanic heat transport, implying a weakening of the North Atlantic Current (NAC). A comparison with Early Pleistocene G. ruber Mg / Ca-based SST records shows a shift in the dominant climatic cycle from precession to obliquity, alongside a marked increase in amplitude, indicating an enhanced influence of obliquity cycles correlated with the expansion of Northern Hemisphere ice sheets.

Pseudopus pannonicus (Squamata), the largest known anguid lizard-Redescription of the type material and new specimens from the Neogene and Quaternary of Hungary and Poland.

Herein, we revise the material of the extinct taxon Pseudopus pannonicus from Central Europe, the largest known anguid lizard and iconic member of herpetofaunas from the Upper Cenozoic of Europe. The geographical position of Polgárdi 2, the type locality of P. pannonicus, as well as several other closely located important localities make Central Europe a valuable area of high interest for studies regarding European Cenozoic palaeoherpetological assemblages. We clarified the nature of the type material of Pseudopus pannonicus, showing that it consisted not only of the five specimens originally figured. Instead, the syntype series also includes a considerable number of specimens from Polgárdi 2 that were only described or figured 12 years after the original description of P. pannonicus. Detailed osteological descriptions are provided for specimens from the type series and Polish specimens, with the aid of high-resolution imaging (SEM and μCT scanning), and intraspecific variability is discussed. The articular surface with the lappet of the parietal overlapping the frontal is discussed as a character potentially relevant for the diagnosis of P. pannonicus. We updated the identification of several specimens of P. pannonicus and discussed the biogeographic implications of such revisions. In Poland, P. pannonicus is an abundant component of Neogene and early Quaternary herpetofaunas, known with certainty from the Middle Miocene of Przeworno (the oldest known occurrence of the species globally), the Early-Late Pliocene of Węże I, the Late Pliocene of Rębielice Królewskie I, the Late Pliocene of Węże II, and the Early Pleistocene of Kadzielnia (one of the youngest occurrences documented globally). An indeterminate anguine with Anguis affinities is newly reported from Rębielice Królewskie II. The taxonomic status of other large anguids from the Neogene of Europe is discussed and we conclude that most are junior synonyms of P. pannonicus. We also show that another purported synonym, that is, Ophisaurus intermedius from the Early Pleistocene of Romania, is instead a nomen nudum. We conducted phylogenetic analyses (18 taxa, 65 characters) to understand the relationship of P. pannonicus relative to other anguid representatives and anguid-related group (i.e., glyptosaurids). A single most parsimonious tree (length: 134 steps) was recovered. The clade Pseudopus is stable, comprising the two distinct sister subclades [Pseudopus laurillardi + Pseudopus ahnikoviensis] and [Pseudopus pannonicus + Pseudopus apodus]. These phylogenetic results are in accordance with previously published works.

Hominin musical sound production: palaeoecological contexts and self domestication

In this article we seek to integrate theories of music origins and dance with hominin fossil anatomy and the paleoecological contexts of hominin evolution. Based on the association between rhythm in music, dance and locomotion, we propose that early bipedal hominins may have evolved neurobiological substrates different from other great apes due to the rhythmic aspects of bipedal walking and running. Combined with the emancipation of the hands resulting from erect posture, we propose that the neurobiological changes necessary for technological innovation, cultural practices and human musical abilities may have evolved, at least in incipient form, much earlier than previously thought. The consequent ability to synchronize movement and sound production may have also proved beneficial as early bipedal hominins ventured out of late Miocene and early Pliocene woodland and forested habitats and into more open habitats with increased predation risk. We also postulate that, along with bipedalism, paedomorphic morphogenesis of the skull at the base of the hominin clade was a necessary prerequisite for the evolution of vocal modulation and singing in later varieties of hominin. To date research into the evolution of music and dance has yet to be integrated with the fossil and paleoecological evidence of early hominin evolution. This paper seeks to fill this lacuna in the extant literature on human evolution. We also suggest that autocatalytic feedback loops evolving synergistically with hominin erect posture, skull and hand morphology, neurochemical processes and the self-domestication syndrome, have been operative from early hominins some 6 Ma to the present. We document this process by reference to primatological, ethnographic, neurochemical and archaeological data.

Species occurrences of Mio-Pliocene horses (Equidae) from Florida: sampling, ecology, or both?

AbstractDuring the late Miocene and early Pliocene (latest Hemphillian, Hh4 interval, 5.7 to 4.75 Ma) a distinctive suite of four species of extinct horses (Family Equidae) were widespread in North America. This includes Nannippus aztecus, Neohipparion eurystyle, Astrohippus stocki, and Dinohippus mexicanus. In Florida, two additional equid species, Pseudhipparion simpsoni and Cormohipparion emsliei, are also typically found at Hh4 localities. Here we compare horses from four Hh4 Florida fossil sites, including three from the Bone Valley mines and a fourth from the recently discovered Montbrook site. Two of these sites have all six expected species, one has five species, and one has only four species present. To explain these differences, we used species counts from research databases and rarefaction simulation to clarify the relative abundances, species richness, and occurrences of these horses from these four sites. The Palmetto Mine (Agrico) site, with five equid species, appears to lack the sixth species owing to ecological reasons. This is different from Montbrook, the site with only four of the six species. Results indicate that Montbrook is likely lacking two missing equid species for a couple of reasons: sampling bias and biological/ecological causes. Our results demonstrate that sampling biases can account for observed equid species richness when the overall abundance of certain equid species is low. Nevertheless, other factors, including ecology and with sufficient resolution, perhaps also time, may also explain the distribution and occurrences of individual species at these and other fossil sites. In a broader perspective, analyses such as this example provide an opportunity to address a persistent challenge in paleontology, that is, how do we explain absences of extinct taxa from the fossil record?

Provenance of the Papuan Peninsula (Papua New Guinea): Zircon Inheritance from Miocene–Pliocene Volcanics and Volcaniclastics

Plate tectonic reconstructions of Papua New Guinea prior to the late Cenozoic are characterized by a lack of provenance data to constrain the relative origin of the allochthonous terranes. At present, plate tectonic reconstructions of this region infer that the accreted New Guinea terranes at the northern Australian continental margin are likely autochthonous or para-autochthonous in nature. This study presents the results of an investigation into zircons derived from Miocene–Pliocene volcanics and volcaniclastics of the Papuan Peninsula. Results from U-Pb zircon geochronology inform the recent geological history of the Papuan Peninsula, with magmatism active in the late Miocene and early Pliocene, between approximately 9 Ma and 4.5 Ma. More significantly, however, is the recognition of extensive inherited zircon grains within the volcanic and volcaniclastic sequences. These inherited zircon grains are most likely sourced from the Owen Stanley Metamorphics, which form the basement rocks of the Papuan Peninsula. Provenance of the inherited zircon grains imply that the Cretaceous volcaniclastic protolith of the Owen Stanley Metamorphics must have had input from continental detritus, but this cannot be derived from North Queensland, Australia as inferred by current reconstructions. Instead, zircon U-Pb age spectra correlate with probable source regions further to the south, adjacent to the Shoalwater Formation of the Central Queensland margin, and New Caledonia. These findings suggest that late Mesozoic and Cenozoic regional reconstructions of eastern Australia and the Southwest Pacific require major revision and that additional work is undertaken to inform the provenance of such allochthonous terranes.

East Asian-North American disjunctions and phylogenetic relationships within subtribe Nepetinae (Lamiaceae)

Biogeographic disjunctions, including intercontinental disjunctions, are frequent across plant lineages and have been of considerable interest to biologists for centuries. Their study has been reinvigorated by molecular dating and associated comparative methods. One of the “classic” disjunction patterns is that between Eastern Asia and North America. It has been speculated that this pattern is the result of vicariance following the sundering of a widespread Acrto-Teritary flora. Subtribe Nepetinae in the mint family (Lamiaceae) is noteworthy because it contains three genera with this disjunction pattern: Agastache, Dracocephalum, and Meehania. These disjunctions are ostensibly the result of three separate events, allowing for concurrent testing of the tempo, origin, and type of each biogeographic event. Using four plastid and four nuclear markers, we estimated divergence times and analyzed the historical biogeography of Nepetinae, including comprehensive sampling of all major clades for the first time. We recover a well-supported and largely congruent phylogeny of Nepetinae between genomic compartments, although several cases of cyto-nuclear discordance are evident. We demonstrate that the three disjunctions are pseudo-congruent, with unidirectional movement from East Asia at slightly staggered times during the late Miocene and early Pliocene. With the possible exception of Meehania, we find that vicariance is likely the underlying driver of these disjunctions. The biogeographic history of Meehania in North America may be best explained by long-distance dispersal, but a more complete picture awaits deeper sampling of the nuclear genome and more advanced biogeographical models.

Biogeographic diversification of Actaea (Ranunculaceae): Insights into the historical assembly of deciduous broad-leaved forests in the Northern Hemisphere

The deciduous broad-leaved forests (DBLFs) cover large temperate and subtropical high-altitude regions in the Northern Hemisphere. They are home to rich biodiversity, especially to numerous endemic and relict species. However, we know little about how this vegetation in the Northern Hemisphere has developed through time. Here, we used Actaea (Ranunculaceae), an herbaceous genus almost exclusively growing in the understory of the Northern Hemisphere DBLFs, to shed light on the historical assembly of this biome in the Northern Hemisphere. We present a complete species-level phylogenetic analysis of Actaea based on five plastid and nuclear loci. Using the phylogenetic framework, we estimated divergence times, ancestral ranges, and diversification rates. Phylogenetic analyses strongly support Actaea as monophyletic. Sections Podocarpae and Oligocarpae compose a clade, sister to all other Actaea. The sister relationship between sections Chloranthae and Souliea is strongly supported. Section Dichanthera is not monophyletic unless section Cimicifuga is included. Actaea originated in East Asia, likely the Qinghai-Tibet Plateau, in the late Paleocene (c. 57 Ma), and subsequently dispersed into North America in the middle Eocene (c. 43 Ma) via the Thulean bridge. Actaea reached Europe twice, Japan twice, and Taiwan once, and all these five colonization events occurred in the late Miocene-early Pliocene, a period when sea level dropped. Actaea began to diversify at c. 43 Ma. The section-level diversification took place at c. 27–37 Ma and the species-level diversification experienced accelerations twice, which occurred at c. 15 Ma and c. 5 Ma, respectively. Our findings suggest that the Northern Hemisphere DBLFs might have risen in the middle Eocene and further diversified in the late Eocene-Oligocene, middle Miocene and early Pliocene, in association with climatic deterioration during these four periods.

Phylogeny of dwarf geckos of the genus Lygodactylus (Gekkonidae) in the Western Indian Ocean.

Diurnal dwarf geckos of the genus Lygodactylus are distributed in tropical and subtropical regions and live in highly diverse habitats. The genus currently comprises 79 species and several candidates for new species or subspecies. Most of these taxa occur in Sub-Saharan Africa and Madagascar, with only two described species in South America. Although the main center of diversity of Lygodactylus currently is Africa, the genus probably has a Malagasy origin, followed by two or three independent transoceanic dispersal events between Madagascar and Africa and one trans-Atlantic dispersal from Africa to South America. A few species colonised islands in the Western Indian Ocean belonging to the Zanzibar Archipelago and to the Îles Éparses. Here we examined L. grotei pakenhami from Pemba Island, L. insularis from Juan de Nova, and L. verticillatus from Europa Island to clarify their taxonomic status and their origin. Concerning L. grotei pakenhami and L. insularis, preceding studies pointed to a relation to species of the African L. capensis group. In contrast, L. verticillatus on Europa Island is considered to be conspecific with Malagasy populations. Therefore, we conducted a phylogenetic study of the African L. capensis group and the Malagasy L. verticillatus group, and examined color pattern, selected morphological characters and two mitochondrial markers (ND2 for African and 16S rRNA for Malagasy Lygodactylus). Lygodactylus grotei pakenhami from Pemba and L. grotei from mainland Africa cannot be distinguished by their scalation, but their reciprocal monophyly suggested by mitochondrial DNA, conspicuously different coloration (both in adults and hatchlings) and their high genetic distances (16.3% in ND2) support the hypothesis that these taxa represent two distinct species. Consequently, we elevate L. grotei pakenhami to species level, as Lygodactylus pakenhami Loveridge, 1941. Lygodactylus pakenhami is endemic to Pemba Island which was possibly separated from the African mainland during the late Miocene or Early Pliocene (6 million years ago). The simplest explanation for the existence of L. pakenhami on Pemba is vicariance. A recent, human-mediated transportation is excluded, as the molecular data clearly indicate a longer period of isolation. Lygodactylus insularis has been supposed to be related to the taxa 'capensis' or 'grotei'. However, it is impossible to discern the relationship of L. insularis, L. capensis and L. grotei by means of scalation or coloration alone. Our molecular phylogenetic analyses reveal that L. insularis is embedded within the L. capensis group, clearly indicating its African origin. The single gene (ND2) as well as the multigene analyses fully support a closer common origin of L. insularis and L. capensis than of L. insularis and L. grotei. However, the position of L. insularis within the clade formed by L. insularis, L. nyaneka, L. capensis sensu stricto and six L. aff. capensis groups is not clearly resolved. Lygodactylus insularis is endemic on Juan de Nova Island, an old low elevation atoll. That all L. insularis mitochondrial sequences are very similar to each other and together form a monophyletic lineage is in agreement with the hypothesis of a single dispersal event to the island. For the L. verticillatus population from Europa Island our mitochondrial data suggest close relationships to conspecific samples from the coastal regions of south-western Madagascar. As we found no relevant morphological or genetic differences between the insular and the Malagasy populations of L. verticillatus, and no remarkable genetic variation within the monophyletic lineage on Europa, we suggest a single, very recent dispersal event, perhaps human-mediated. Although the genus Lygodactylus colonised Africa, islands in the Gulf of Guinea, South America and some islands in the Western Indian Ocean, it seems-compared to other lizard genera-to be only moderately successful in transoceanic long-distance dispersal.

Revealing the Stygobiotic and Crenobiotic Molluscan Diversity in the Caucasus: Part IV—Crenobiotic Belgrandiellinae Radoman, 1983 (Mollusca, Hydrobiidae) from Georgia

Since 2020, the south-western Caucasus has been recognized as a hotspot of stygobiotic Mollusca diversity after revealing a large number of new, range-restricted species within the spring snail family Hydrobiidae, subfamily Sadlerianinae sensu Szarowska. Meantime, based on extensive material collected in the south-western Caucasus during the last decades, we studied members of another spring snail subfamily Belgrandiellinae Radoman, 1983. Modern integrative taxonomic work revealed hitherto unknown diversity within this subfamily in the region and further proved the importance of the south-western Caucasus as a hotspot of stygobiotic life. In particular, the subterranean environment and springs of Georgia were known to be inhabited by the genus Tschernomorica Vinarski and Palatov, 2019 with four nominal species. Our research, based on a morpho-anatomical study and genetic investigation of COI/H3 mitochondrial/nuclear markers, revealed additionally seven species and three genera new to science—Colchiella lugella gen. et sp. nov., C. nazodelavo gen. et sp. nov., C. shiksa gen. et sp. nov., C. dadiani gen. et sp. nov., Sataplia cavernicola gen. et sp. nov., Aetis starobogatovi gen. et sp. nov., and Tschernomorica kopidophora sp. nov. —to inhabit the Georgian part of south-western Caucasus. The full taxonomic description of each new taxa, along with the review of habitat characteristics and conservation status, is provided. Molecular genetics suggests that the ancestors of Caucasian Belgrandiellinae have migrated from south-western Europe, probably more than once during the late Messinian and early Pliocene periods. Later, Plio-Pleistocene climate oscillations, particularly the repeated rise and fall of the Black Sea water level, resulted in the isolation and radiation of various lineages within the Caucasus and Crimea.

A Global Reassessment of the Spatial and Temporal Expression of the Late Miocene Biogenic Bloom

AbstractThe Late Miocene Biogenic Bloom (LMBB) is a late Miocene to early Pliocene oceanographic event characterized by high accumulation rates of opal from diatoms and calcite from calcareous nannofossils and planktic foraminifera. This multi‐million year event has been recognized in sediment cores from the Pacific, Atlantic, and Indian Oceans. Based on existing studies, it is not clear whether the LMBB is a global omnipresent event, or whether it is restricted to certain regions or oceanographic environments. Moreover, the origin of this event is still widely discussed. In this study, we aim to provide a comprehensive overview of the geographical and temporal aspects of the LMBB by compiling published ocean drilling (DSDP, ODP, and IODP) records of sedimentation rates, and CaCO3, opal, and terrigenous accumulation rates that cover the late Miocene and early Pliocene interval. Our data compilation shows that manifestations of the LMBB are present in many different locations but in a very heterogeneous way. The compilation shows that the sites where the LMBB is expressed are mainly located in areas with a high productivity regime (i.e., upwelling systems). We suggest that one of the possible hypotheses to explain the onset of the LMBB could be a global increase in upwelling intensity due to an increase in wind strength or an increase in deep water formation, ramping up global thermohaline circulation.

Diversification trajectories and paleobiogeography of Neogene chondrichthyans from Europe.

Despite the rich fossil record of Neogene chondrichthyans (chimaeras, sharks, rays, and skates) from Europe, little is known about the macroevolutionary processes that generated their current diversity and geographical distribution. We compiled 4368 Neogene occurrences comprising 102 genera, 41 families, and 12 orders from four European regions (Atlantic, Mediterranean, North Sea, and Paratethys) and evaluated their diversification trajectories and paleobiogeographic patterns. In all regions analyzed, we found that generic richness increased during the early Miocene, then decreased sharply during the middle Miocene in the Paratethys, and moderately during the late Miocene and Pliocene in the Mediterranean and North Seas. Origination rates display the most significant pulses in the early Miocene in all regions. Extinction rate pulses varied across regions, with the Paratethys displaying the most significant pulses during the late Miocene and the Mediterranean and North Seas during the late Miocene and early Pliocene. Overall, up to 27% and 56% of the European Neogene genera are now globally and regionally extinct, respectively. The observed pulses of origination and extinction in the different regions coincide with warming and cooling events that occurred during the Neogene globally and regionally. Our study reveals complex diversity dynamics of Neogene chondrichthyans from Europe and their distinct biogeographic composition despite the multiple marine passages that connected the different marine regions during this time.

Following the aridity: Historical biogeography and diversification of the Philodromidae spider genus Petrichus in South America

Aridity conditions and expansion of arid biomes in South America are closely linked to the onset of Andean orogeny since at least 30 Mya. Among arid-associated taxa, spiders belonging to the genus Petrichus are found along the Andes mountains and across the diagonal of open formations of the Chaco and Cerrado domains. In this contribution, we asked whether Petrichus originated prior to the central Andean uplift and what historical processes have promoted their diversification. We time-calibrated the phylogenetic tree of Philodromidae and estimated the divergence times of Petrichus. Considering phylogenetic uncertainty, we assessed biogeographical hypotheses of the historical events associated with the diversification of these spiders in South America. Petrichus originated along the Pacific coastal deserts in the Central Andes during the Early Miocene. The species likely dispersed from the western to the eastern side of the Andes coincidently with the central Andean uplift. The diversification of these spiders is coeval with the expansion of open grassland formations during the Late Miocene and Early Pliocene. Multiple dispersal events occurred from the Monte desert to southern South America and eastward to Chaco between ∼ 8 and 2.5 Mya. The Andes might have played a role as a corridor favoring geographical range expansions and colonization of new environments. In addition, we also suggest that Philodromidae might have an Oligocene origin or earlier. Future analyses based on further evidence and larger taxon sampling should be carried out to corroborate our findings.

High-resolution sequence stratigraphy of complex gas reservoirs: Patao and Dragon fields, offshore Venezuela

The stratigraphic complexity of near-shore depositional systems, together with the occurrence of submarine mass-failure deposits in the area of the Patao and Dragon fields, represents a challenge for devising a development plan for the gas reservoirs identified in the area. The high drilling costs in offshore areas and the sparse knowledge in this frontier basin require an integration of all available data to optimize the development of production projects. This work aims to refine the geological model, particularly with respect to understanding the complexity of the sedimentary deposits in this area and its impact on the exploitation of the associated reservoirs. The Patao and Dragon fields belong to the Carupano Basin, offshore northeastern Venezuela, and contain hydrocarbon accumulations mostly trapped in late Miocene and early Pliocene clastic reservoirs. Existing well data in the area are still relatively scarce, but provide valuable calibration of the available seismic data. This study involves the construction of a sequence stratigraphic framework, based on the integration of sedimentological and petrophysical studies, vertical proportion curves of lithofacies (VPC), seismic-stratigraphic interpretation, petro-acoustic characterization, and reservoir analysis, which enable the identification of stratigraphic units and the correlation between wells. Seven systems tracts have been identified, including the FSST3 (falling-stage systems tract 3) and TST3 (transgressive systems tract 3) which host the most prolific gas reservoirs in the area, comprised of coalescent sands with distinctive rocks properties. There is evidence that the FSST3 is affected by syn-depositional submarine mass movement that distorted the sedimentary architecture and the internal structure of the deposits. These considerations, as well as the identification of potential permeability barriers associated with marine flooding surfaces, allowed the establishment of different scenarios of hydraulic unit configuration, key for the evaluation of these gas reservoirs in terms of their storage capacity and subsequent production.

Historical dispersal and host-switching formed the evolutionary history of a globally distributed multi-host parasite – The Ligula intestinalis species complex

Studies on parasite biogeography and host spectrum provide insights into the processes driving parasite diversification. Global geographical distribution and a multi-host spectrum make the tapeworm Ligula intestinalis a promising model for studying both the vicariant and ecological modes of speciation in parasites. To understand the relative importance of host association and biogeography in the evolutionary history of this tapeworm, we analysed mtDNA and reduced-represented genomic SNP data for a total of 139 specimens collected from 18 fish-host genera across a distribution range representing 21 countries. Our results strongly supported the existence of at least 10 evolutionary lineages and estimated the deepest divergence at approximately 4.99–5.05 Mya, which is much younger than the diversification of the fish host genera and orders. Historical biogeography analyses revealed that the ancestor of the parasite diversified following multiple vicariance events and was widespread throughout the Palearctic, Afrotropical, and Nearctic between the late Miocene and early Pliocene. Cyprinoids were inferred as the ancestral hosts for the parasite. Later, from the late Pliocene to Pleistocene, new lineages emerged following a series of biogeographic dispersal and host-switching events. Although only a few of the current Ligula lineages show narrow host-specificity (to a single host genus), almost no host genera, even those that live in sympatry, overlapped between different Ligula lineages. Our analyses uncovered the impact of historical distribution shifts on host switching and the evolution of host specificity without parallel host-parasite co-speciation. Historical biogeography reconstructions also found that the parasite colonized several areas (Afrotropical and Australasian) much earlier than was suggested by only recent faunistic data.

Recognizing the Role of Tropical Seaways in Modulating the Pacific Circulation

AbstractVarious modeling studies have examined the climatic effects of either the Central American Seaway or the Indonesian seaway. The co‐existence of these two tropical seaways may have a greater influence than the existence of a single seaway. Although the dual seaway situation is closer to that reconstructed during Miocene/Pliocene, relevant studies remain scarce. Here, we investigate the co‐effects of dual tropical seaway changes on the Pacific circulation through a set of sensitivity experiments. Our results show that the combined shallow opening of tropical seaways can generate an active Pacific meridional overturning circulation and maintain strong upwelling conditions along the equatorial Pacific, which may have helped favor a “biogenic bloom” during the late Miocene and early Pliocene. Moreover, the logically successive closure of the tropical seaways can provide patterns of zonal sea surface temperature gradients that are similar to those recorded in the equatorial Pacific from the late Miocene to the Pliocene.

New well-preserved materials of Glossotherium chapadmalense (Xenarthra, Mylodontidae) from the Pliocene of Argentina shed light on the origin and evolution of the genus

ABSTRACT Fossil remains of extinct mylodontine sloths have been discovered in numerous localities throughout the American supercontinent, but knowledge of them is still mainly centered on the Pleistocene forms rather than their Neogene relatives. In this contribution, previously unpublished cranial and postcranial materials herein ascribed to Glossotherium chapadmalense (Kraglievich), coming from the Pliocene Chapadmalal Formation (Province of Buenos Aires, Argentina), are presented. These remains are described and compared with those of other mylodontine species from South and North America, providing an exhaustive characterization of cranial morphology in G. chapadmalense and some preliminary insights into its postcranial anatomy. The results have revealed a unique combination of differences and similarities of this enigmatic species with the larger-sized representatives of Glossotherium. In addition, these materials allowed shedding light on the long-standing uncertainties regarding its taxonomic status, as this form has been alternately considered to belong to the genera Glossotherium or Glossotheridium over the last century. As a result, the genus Glossotherium was present, at least, at the Early–Late Pliocene transition in the Pampean region of Argentina, and is recorded by the Upper Pleistocene throughout the entire South American continent. The radiation of the Pleistocene species is associated with a consistent body mass increase that was probably a response to the cooling temperatures and higher predation pressure in South America during the Late Pliocene–Early Pleistocene. These phenomena were probably driven by the stable emergence of the Panamanian Isthmus around 3 Ma and the successive faunal turnover pulses of the Great American Biotic Interchange.

Cenozoic Antarctic Peninsula Temperatures and Glacial Erosion Signals From a Multi‐Proxy Biomarker Study

AbstractTerrestrial climate records for Antarctica, beyond the age limit of ice cores, are restricted to the few unglaciated areas with exposed rock outcrops. Marine sediments on Antarctica's continental shelves contain records of past oceanic and terrestrial environments that can provide important insights into Antarctic climate evolution. The SHALDRIL II (Shallow Drilling on the Antarctic Continental Margin) expedition recovered sedimentary sequences from the eastern side of the Antarctic Peninsula of late Eocene, Oligocene, middle Miocene, and early Pliocene age that provides insights into Cenozoic Antarctic climate and ice sheet development. Here, we use biomarker data to assess atmospheric and oceanic temperatures and glacial reworking from the late Eocene to the early Pliocene. Analyses of hopanes and n‐alkanes indicate increased erosion of mature (thermally altered) soil biomarker components reworked by glacial erosion. Branched glycerol dialkyl glycerol tetraethers from soil bacteria suggest similar air temperatures of 12°C ± 1°C (1σ, n = 46) for months above freezing for Eocene, Oligocene, and Miocene timeslices but much colder (and likely shorter) periods of thaw during the Pliocene (5°C ± 1°C, n = 4) on the Antarctic Peninsula. TEX86‐based (Tetraether index of 86 carbons) sea surface temperature estimates indicate ocean cooling from 7°C ± 3°C (n = 10) in the Miocene to 3°C ± 1°C (n = 3) in the Pliocene, consistent with deep ocean cooling. Resulting temperature records provide useful constraints for ice sheet and climate model simulations seeking to improve understanding of ice sheet response under a range of climate conditions.

Paleoclimatic and palaeoceanographic changes coupled to the Panama Isthmus closing (13–4 Ma) using organic proxies

This study reconstructs the climatic and oceanographic changes from 13 to 4 Ma at Ocean Drilling Program (ODP) Sites 999 (Caribbean) and 1241 (East Pacific) during Panama Isthmus closure. We used lipid biomarkers as marine production indicators and organic proxies (U37K´ and TEX86H) to estimate ocean surface and thermocline temperatures. Enhanced terrestrial input during the first 3 Ma of the record, possibly coupled to tectonic processes, may have triggered higher surface productivity at both sides of the Isthmus. Even though marine production is generally higher in the tropical Pacific, a peak in alkenone production at 12.4–10.6 Ma indicates unrestricted inflow of nutrient-rich waters into the Caribbean. Higher production is observed during the global late Miocene biogenic bloom (LMBB 8–4.5 Ma) coupled to enhanced nutrients from terrestrial sources and/or upwelling. We find a good correspondence between U37K´ and modern sea surface temperature (SST). The TEX86H is a good tracer for thermocline values, however, the deeper Thaumarchaeota distribution in the Caribbean may result in an underestimation of absolute temperatures at ODP Site 999. None the less, temperature records at both Sites show similar trends coupled to global climate dynamics, therefore Isthmus build up did not significantly affect surface or thermocline temperatures at a regional level. Globally reported decreasing temperatures during the late Miocene and early Pliocene coupled to decreasing CO2 levels are registered at both Sites down to at least 200 m. The late Miocene warm period (LMWP 9.5–7 Ma), late Miocene cold period (LMC 7–5.4 Ma) and the Pliocene warm period (PWP 4–3.5 Ma) are reflected by our temperature records confirming global climate is the main driver of temperature evolution in the study area. The reconstructed temperatures are mainly coupled to atmospheric forcing in the Caribbean, with a deviation possibly due to inflow of colder Pacific intermediate waters. While at ODP Site 1241 temperatures are mainly controlled by global climate, the Site also reflects changes in the water column as it migrates interacting with the complex current structure of the tropical Pacific. Decoupled temperature patterns at both Sites are related with differential changes in water column structure partially masking the climatic signal. Therefore, we could establish that while tectonic processes and related terrestrial input increases as well as upwelling control production and water column structure, climate in the study area remained tuned to global patterns regardless of Isthmus closure stage.

Mid-Miocene to recent tectonic evolution of the Punta Stilo Swell (Calabrian Arc, southern Italy): An effect of Calabrian Arc migration

The development of Punta Stilo Swell (PSS), a submerged lobate-shaped promontory located in the Crotone-Spartivento Basin, is inferred to be closely linked to the Calabrian Arc kinematics since mid-Miocene onward. The latter consists of an alternation between long-term phases of subsidence related to forward migration of the Calabrian accretionary complex, and short-term compressional-transpressional phases, characterized by episodes of uplift and formation of regional unconformities, in a context of stopping or slowdown of Calabrian accretionary complex migration. In particular, the study area is supposed to have respectively experienced phases of compressional and extensional tectonics during late Messinian and early Pliocene, which likely produced a reactivation of inherited compressional and extensional structures. Late Pliocene/Pleistocene transtensional tectonics is documented along the offshore extension of the Soverato-Lamezia Fault Zone (SLFZ), in the N sector of the PSS. The resulting physiographic modifications associated with such compressional, extensional and transtensional tectonics is believed to have controlled the accumulation of the thick Plio-Pleistocene succession of the PSS. The northern continental slope is inferred to be the result of late Pliocene/Pleistocene transtensional tectonics occurred along the SLFZ, whereas the shelf break is considered the result of an early Pliocene extensional tectonics. The considerable steepness (>10°) of the southern and eastern continental slope of the PSS is associated with the late Messinian compressional tectonic activity and is marked by the occurrence of slope failure-associated events.