Early Middle Miocene Research Articles

REVISION OF THE MIOCENE CAVIOMORPH RODENTS FROM THE RÍO SANTA CRUZ (ARGENTINEAN PATAGONIA)

Fossil rodents from the Río Santa Cruz (RSC) classic localities (Santa Cruz Formation, Early–Middle Miocene) are known by the works of F. Ameghino and W.B. Scott since the end of the 19th and beginning of the 20th centuries. These caviomorph rodents have not been comprehensively reviewed since then. In this contribution, we studied new fossil specimens from the cliffs of the RSC (Province of Santa Cruz, Argentina) collected with accurate stratigraphic and geographic data during fieldtrips in 2013 and 2014. An increase in the caviomorph taxonomic richness is observed, based upon our taxonomic study of caviomorphs previously recorded in the RSC. Also, these fieldworks recovered for the first time several taxa previously found in other Santacrucian and even older Patagonian localities (Colhuehuapian, Early Miocene). As a general evolutionary pattern, we note an increase of derived euhypsodont taxa (Prolagostomus, Pliolagostomus, Schistomys, and Eocardia) in Segundas Barrancas Blancas (16.47–15.3 Ma). In addition, a taxonomic replacement of Phanomys by Schistomys is noted between Barrancas Blancas (17.21–16.3 Ma) and Segundas Barrancas Blancas, as well as a notably increase in the abundance of the large Perimys onustus in the latter locality. The present study provides a revision of the caviomorph systematics, and intends to be the starting point to understand the diversity (in all its aspects) and the evolution of this group during the Santacrucian, a major event in the South American mammalian history.

EARLY MIOCENE SLOTHS (XENARTHRA, FOLIVORA) FROM THE RÍO SANTA CRUZ VALLEY (SOUTHERN PATAGONIA, ARGENTINA). AMEGHINO, 1887 REVISITED

The first detailed geological and paleontological survey of the Santa Cruz Formation (Early–Middle Miocene; Burdigalian–early Langhian) along the Río Santa Cruz was carried out in 1887 by Carlos Ameghino, who recovered more than 2000 fossil remains. In that same year, his brother Florentino studied and reported these remains, recognizing 122 taxa, of which 110 were new species. Fourteen of these new species were of sloths (Xenarthra, Folivora). In this contribution we report and describe new fossil sloth remains recovered in recent expeditions (between 2013 and 2014) along the southern banks of the Río Santa Cruz. The new specimens were recovered from two localities: Barrancas Blancas and Segundas Barrancas Blancas. We review the taxonomic richness of fossil sloths, in comparison with other Santacrucian localities recently studied, e.g, from the Atlantic coast and from the Andean region. An analysis of the original taxa erected by Ameghino is also included. As several of the original fossils on which these taxa are based are no longer available, we explore the value of the new collection in helping resolve systematic issues, as well as considering the specimens that formed the basis for the species erected by Ameghino in 1887. Further, the degree to which W.B. Scott’s systematic decisions on the Santacrucian sloths, published in 1903 and 1904, should continue to be recognized is also assessed.

Stratigraphy revision of upper Badenian of Rakovica stream near Belgrade (Central Paratethys, Serbia)

Belgrade area is a region of high paleobiodiversity, being ranked among the best known in Serbia. The prominent position among a number of Middle Miocene (Badenian) fossiliferous sites in the vicinity of Belgrade (southern Pannonian Basin, Central Paratethys) are occupied with sediments of Rakovica stream, also known as ?Rakovica sands?. Here, the integrated evidence based on new fossil findings of calcareous nannoplankton, foraminifera and molluscs assemblages, allows the stratigraphic revision of the clastic facies of the Rakovica succession. Based on the studies of lithological composition, high paleodiversity molluscs fauna and local palaeogeographical setting, it can be concluded with reasonable certainty that deposits of Rakovica stream entitled ?Rakovica sand? represents a sandstone of the shallow marine (littoral) environment during Lower Badenian time. Large benthic foraminifera Ammonia viennensis (d?ORBigny), and Borelis haueri (d?ORBigny) as well as zone marker nn5 Sphaenolithus heteromorphus defLandRe correspond to this biostratigraphic level. during the late early Miocene and Middle Miocene (Badenian), the climate in the Central Paratehys was mainly subtropical. This is supported at its southern margin by the presence of thermophilous mollusc taxa, as well as the Conidae, Strombidae, Xenophoridae, Pleurotomidae, Turridae, Muricidae, etc. Consequently, the investigated deposit can be ascribed to the early Badenian which biostratigraphically corresponds to the nn5 nannozone by correlation with successions in theirs type-areas to the Central Paratethys, and defines preciously the time of the marine transgression in this area.

THE METATHERIA FROM THE RÍO SANTA CRUZ (SANTA CRUZ FORMATION, EARLY-MIDDLE MIOCENE, ARGENTINA): HISTORY AND NEW RECORDS

Here we summarize the species of Metatheria from the Early–Middle Miocene Santa Cruz Formation at the Río Santa Cruz (RSC; Argentina). We assign newly collected specimens from the RSC localities Barrancas Blancas (BB) and Segundas Barrancas Blancas (SBB) to the known metatherian species. The metatherians from RSC were first described by F. Ameghino in 1887. He did not always establish clearly the type specimens of the species he founded, and often later he chose new type specimens. This led to confusion by future authors when they assumed they were looking at the original types when in fact they were the substitutes. We evaluated the actual and supposed type specimens from the RSC. We have identified the holotype of the Paucituberculata Palaeothentes aratae Ameghino and its calcotype. Following the International Code of Zoological Nomenclature (Art. 75), we formally propose neotypes, for the species Sipalocyon gracilis Ameghino (Sparassodonta) and for Microbiotherium patagonicum Ameghino (Microbiotheria). The species Perathereutes pungens Ameghino (Sparassodonta), previously known only from coastal localities, is described for the first time for the RSC. In total, we recognized 16 metatherian species for the RSC: seven Paucituberculata, seven Sparassodonta, and two Microbiotheria. Ten of the 16 species were recorded from recent fieldtrips. All 10 are recorded from SBB, six come from BB, and none from a third RSC locality, Yaten Huageno.

New Species of Turbo (Marmarostoma) (Gastropoda, Turbinidae) from the Miocene Limestone in Central Japan: A Window into the Miocene Marine Biodiversity in the Northeastern Philippine Sea

The late early to middle Miocene limestone bodies in the Sagara and Izu Peninsula areas of central Japan are reefal deposits that were deposited under a tropical climate and provide a window into the paleodiversity of tropical volcanic islands in the northeastern Philippine Sea Plate. Specimens from the early middle Miocene Megami Limestone in the Sagara area and from the middle Miocene limestone blocks within the Yugashima Group on the Izu Peninsula are described as Turbo (Marmarostoma) histrioides sp. nov. and Turbo (Marmarostoma) izuensis sp. nov., respectively. Discovery of these two new species raises the number of Marmarostoma species from four to six in the Sagara and Izu Peninsula areas, demonstrating that the subgenus was more diverse in the northeastern Philippines Sea Plate during the middle Miocene than it is today. In particular, there are double the number of Marmarostoma species (four species) from the middle Miocene in the Izu Peninsula compared with the modern fauna on the tropical islands of the Izu-Ogasawara Arc. The highest richness of modern species of Marmarostoma is found in the central Indo-West Pacific, where molecular phylogenetic studies have suggested that the subgenus rapidly diversified in the late Oligocene or early Miocene. Nevertheless, Miocene species of this subgenus are sparse in the central IWP, being incongruent to the diversity pattern expected from the molecular studies. The findings reported herein provide an insight into the origin of the central IPW biodiversity hotspot.

NEW RECORDS OF BIRDS IN THE SANTA CRUZ FORMATION (EARLY-MIDDLE MIOCENE) AT THE RÍO SANTA CRUZ VALLEY, PATAGONIA, ARGENTINA

The Santa Cruz Formation constitutes one of the most representative units of the Early-Middle Miocene of South America for its abundant and rich fossil record of vertebrates. The diversity of extinct birds is known so far by at least 17 species grouped in 15 genera and at least 10 families. Most of the avian taxa described from these levels come from localities of the Santa Cruz Province placed next to or along the Atlantic coast. New specimens recovered from the Río Santa Cruz valley, with accurate geographic and stratigraphic provenances, are presented in this contribution. They include rheids, tinamids, and phorusrhacids.

DIPLODON CF. COLHUAPIENSIS (BIVALVIA - HYRIIDAE) IN THE SANTA CRUZ FORMATION (EARLY-MIDDLE MIOCENE), AT THE RÍO SANTA CRUZ, PATAGONIA, ARGENTINA. STRATIGRAPHIC AND PALEOENVIRONMENTAL CONSIDERATIONS

The Santa Cruz Formation (Early–Middle Miocene) is one of the most widespread sedimentary units of the Argentine Patagonia. This unit contains an abundant and taxonomically diverse fossil vertebrate fauna, especially in mammals. Thus, the paleoecological and paleoenvironmental information derives mainly from the analysis of the vertebrate assemblages, as well as from the ichnological and paleobotanical evidence. The record of freshwater bivalves assigned to the species Diplodon cf. colhuapiensis Ihering, 1903 from the Santa Cruz Formation, collected in the locality of Barrancas Blancas (Estancia Santa Lucía), at Río Santa Cruz, allows us to infer the particular paleoenvironmental conditions setting during the deposition of the bearing levels. Considering this record, we propose that Diplodon, which was originally assigned to the “Sehuenense stage” (piso sehuenense of F. Ameghino), could have come from the Early–Middle Miocene of the Santa Cruz Formation. In this sense, the specimens referred to Diplodon cf. colhuapiensis suggest the existence of an established community of Hyriidae mollusks at the upper-middle levels of the Santa Cruz Formation. The presence of freshwater bivalves suggests that the depositional environment of this unit included the existence of water courses. The identification of the genus in the Santa Cruz Formation validates its presence in the Early Miocene and extends its southern distribution to the latitude of Río Santa Cruz (~ 50o S).

STRATIGRAPHY AND DEPOSITIONAL ENVIRONMENTS OF THE SANTA CRUZ FORMATION (EARLY-MIDDLE MIOCENE) ALONG THE RÍO SANTA CRUZ, SOUTHERN PATAGONIA, ARGENTINA

Fil: Cuitino, Jose Ignacio. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Centro Nacional Patagonico. Instituto Patagonico de Geologia y Paleontologia; Argentina

Rare diatom Stauroneis balatonis Pantocsek recorded in Lake Savsko, Serbia

Abstract Although well represented in the fossil diatom flora throughout Europe and Asia, from the early-middle Miocene to the Quaternary, Stauroneis balatonis is considered a very rare diatom with a contemporary distribution limited to two ancient lakes – Ohrid and Prespa. The objective of this study was to describe the first finding of S. balatonis in Serbia in Lake Savsko and to update information on the distribution and ecology of this rare species. Periphyton samples were collected from artificial substrates incubated at three depths (0.5 m, 0.8 m and 1.4 m) in Lake Savsko and the epilithic community was sampled in the littoral zone. Samples were collected weekly in summer 2014, from mid-July to mid-September. Diatom permanent slides were prepared and small numbers of S. balatonis specimens were observed only in samples collected in September from artificial substrates incubated at the greatest depth (1.4 m). Our results significantly contribute to the information on the contemporary distribution and the ecology of this rare diatom taxon, especially considering the fact that S. balatonis specimens were observed in our study in diatom communities developed on artificial substrates and in an urban reservoir, i.e. Lake Savsko.

Assessment of the eruptive activity and identification of the mud breccia's source in the Olimpi mud volcano field, Eastern Mediterranean

Even though the intensity and frequency of the eruptive episodes of deep-sea mud volcanoes (MVs) substantially regulate the methane fluxes into the hydrosphere and the development of the near-seafloor sulfate zone that affects the position of the gas hydrate stability zone, these factors are not yet adequately investigated. Moreover, the evaluation of the eruptive sediment's thermal maturity may provide solid documentation of the petroleum generation potential in high depths below seafloor (bsf). Hence, the present study, through the integration of sedimentary facies analysis with hydrocarbon biomarker analysis (based on the concentrations of long-chain (C25–C35) n-alkanes, hopanes and steranes), supported by swath bathymetry data, examined five sediment cores recovered from the Gelendzhik, Moscow, Milano, Leipzig and Heraklion MVs of the Olimpi mud volcano field (OMVF) on the central Mediterranean Ridge. The main objective of this investigation was to assess the ‘modern’ eruptive activity in the OMVF and identify the mud breccia's origin and mobilization depth (based on its maturity level), and the ages of the source beds. Among the studied MVs, Milano, Leipzig and Heraklion appear ‘recently’ active, while Moscow perhaps remains in dormancy for at least one century. The eruptive activity in the OMVF seems to be, generally, vigorous and persistent, while it is linked with several source beds of variable stratigraphy or environmental condition. The multiple eruptive episodes, occurring as uninterrupted events or via pulses, create conditions that perhaps favour high releases of methane into the water column as well as the growth of the gas hydrate phase near the seafloor. The identified ‘modern’ mudflows appear thermally immature for oil generation, while they most probably originate from terrestrial source beds located not deeper than 2 km bsf. A Messinian age could be suggested for the principal sources of the very soft to soft mud breccias of the OMVF, while stratigraphic horizons of Early-Middle Miocene might be proposed as the likely major sources for the firm to very stiff mud breccias of the area.

Fold-and-thrust deformation of the hinterland of Qilian Shan, northeastern Tibetan Plateau since Mesozoic with implications for the plateau growth

The northeastern margin of the Tibetan Plateau (NETP) represents an ideal site to probe the far-field effects and plateau growth in response to the collisions of Eurasia Continent with India Plate and intervening terranes. Here, we investigate the fold-and-thrust deformation of the Shule River region in the hinterland of Qilian Shan, NETP since Mesozoic, based on geological mapping and structural analysis to evaluate the role of multiple-phase deformation in plateau rise and growth. The structural style of the Shule River region is dominated by the foreland-verging Liuhuang Shan fold-and-thrust belt (LHTB) to the southwest and the hinterland-verging Tuolai Nan Shan fold-and-thrust belt (TLTB) to the northeast, separated by the Cenozoic Shule River intermontane basin. Integrated with published thermochronological, sedimentological and structural data, our study reveals four significant deformation phases in the NETP since the Mesozoic. During the Late Triassic to Early Jurassic time, the regional deformation spread in the NETP and produced the Jura-type folds and related thrusts of the LHTB in the study area under the NE-SW-directed compression, and was likely driven by the collision between the Qiangtang and Kunlun terranes. During the late Early Cretaceous, the continuous Lhasa-Qiangtang collision induced reactivation of the LHTB and an extensive exhumation event in the NETP. Since the Early Eocene, the upper crustal shortening and initial uplift of the NETP have accommodated the far-field stress of India-Eurasian collision. Given the widespread Miocene uplift event in the NETP, revealed by previous studies, we attribute the southwestward thrusting of the TLTB and tight-isoclinal syncline of the Oligocene-Miocene Baiyanghe Formation to the significant crustal shortening and topographical growth of NETP during the Early-Middle Miocene. The reactivation of TLTB and newly generated low-angle reverse faults represent gently tilted deformation and plateau growth in response to surface uplift of NETP as a whole since the Late Miocene. Our results imply that the multiple-phase deformation in the NETP since the Late Triassic should have been a first-order control on plateau growth.

Depositional environments and landscapes of the upper Miocene Ipururo Formation at Shumanza, Subandean Zone, northern Peru

During the late Miocene, the Andean–Amazonian region experienced drastic climatic and environmental changes, notably due to a major phase in the Andean uplift. The fossil record is virtually undocumented for this period in the Subandean Zone, where very few palaeoenvironmental and palaeontological investigations have been undertaken. Here, we describe plant remains (pollen, spores, and leaves), microfossils, mollusks, and vertebrates from the Ipururo Formation at Shumanza, San Martín, Peru. Twenty-nine plant families are identified from 164 pollen grains and 89 spores, among them Lycophytes, Monilophytes, and angiosperms (5 monocots and 18 eudicots). The pollen sample notably includes Grimsdalea magnaclavata, Palaeosantalaceaepites cingulatus, Echitricolporites spinosus, and Fenestrites longispinosus, pointing to a late Miocene–early Pliocene age for the TAR-27 locality (10.06–3.72 Ma). Leaf impressions, from nearby localities in the same section, document Malvaciphyllum sp. (Malvaceae), three morphs resembling Caryocaraceae, Fabaceae, Myrtaceae, and two unidentified ‘Dicotyledonae’ angiosperms. The mollusk assemblage is somewhat reminiscent of early–middle Miocene Pebasian faunas and dominated by gastropods (ampullariids, cochliopid, cerithioid, and planorbids). It also includes sphaeriid and unionoid bivalves. Vertebrate recovery is very poor, with a serrasalmine characiform and unidentified actinopterygian teeth. Fossil assemblages and sedimentary facies consistently testify to the dominance of riverine/alluvial forests and the persistence of a steady lowland rainforest close to the Andes less than 10.1 million years ago, without indication of (1) mangrove/marine environments or (2) high-elevation ranges in the close surroundings of Shumanza by that time. By coupling palynostratigraphy and lithostratigraphy, Shumanza fossil assemblages would be further assigned an early late Miocene age (10.1–ca. 8 Ma).

The Key to Understanding the European Miocene Chalcides (Squamata, Scincidae) Comes from Asia: The Lizards of the East Siberian Tagay Locality (Baikal Lake) in Russia.

The early middle Miocene (MN 5) lizards from the East Siberian Tagay locality (Baikal Lake, Russia) in Asia are described here. The lizard fauna consists of two clades, Lacertidae and Scincidae. The skink material is allocated to Chalcides. While this taxon was previously reported from Europe, it has rarely been observed in the Neogene record with only jaw fragments and frontal bones described. Its taxonomy was therefore enigmatic. The Tagay material is almost identical to the European fossils of Chalcides from Austria and Hungary, but it also contains the parietal bone. While the material is also similar to the extant Ch. ocellatus, it exhibits several morphological differences. A new species is therefore erected-Chalcides augei sp. nov. These findings further support the connection of the Baikal Lake area with central Europe during the first half of the Miocene. The comparative anatomy of the frontals, parietals and lower jaws was evaluated by micro-CT in selected skink taxa. This comparison highlights several important differences, for example, paired frontals are present in Broadleysaurus (an outgroup taxon), in Acontias and all studied members of Scincidae herein. The character optimization in Mesquite supports fused frontals as being the condition at the basal node of the Ateuchosauridae + Sphenomorphidae + Eugongylidae + Lygosomidae + Egerniidae + Mabuyidae clade. While the parapineal foramen is restricted to the parietal in most taxa studied herein, it is absent (or vestigial) in Acontias and Feylinia. In contrast to all other skinks, this foramen is located on the frontal in Ateuchosaurus chinensis. Anat Rec, 2019. © 2019 American Association for Anatomy Anat Rec, 303:1901-1934, 2020. © 2019 American Association for Anatomy.

Turritellidae (Gastropoda) of the Miocene Paratethys Sea with considerationsabout turritellid genera.

We present a critical evaluation of the taxonomy, stratigraphy and biogeography of the turritellid gastropods of the Miocene Paratethys Sea. 159 species-level names and 6 infrasubspecific names have been used for Paratethyan Turritellidae since 1848. Of these, only 35 species are accepted herein as valid species, with some uncertainties due to poor preservation or limited access to type material. Maximum diversities occurred during the early middle Miocene (Langhian, Badenian) coinciding with the Miocene Climatic Optimum. Whilst early Miocene turritellid assemblages are characterized by large to very large species of Peyrotia, Turritella and Allmonia, middle Miocene assemblages are predominated by medium-sized species of Archimediella, Helminthia, Oligodia and Ptychidia. The taxonomic composition of these faunas, with representatives of Archimediella, Helminthia, Mesalia and Vermicularia suggests a biogeographic affiliation with Atlantic and especially West African faunas. Turritellinella new gen. is established as new genus for the eastern Atlantic-Mediterranean Turritella tricarinata/communis complex. Viennella is described as new genus with Turritella incisaeformis Csepreghy-Meznerics 1956 as type species. Allmonia new gen. is introduced as new genus for European Cenozoic Protominae previously placed in Protoma. For the first time, inner lirae are documented as conchological features of Turritellidae. Six species are described as new, three within the Turritellinae: Archimediella carpathica new sp., Ptychidia erynella new sp. and Viennella ignorata new sp., and three within the Pareorinae: Mesalia sovisi new sp., Mesalia stryriaca new sp. and Mesalia bohnhavasae new sp.. Ptychidia austrorotundata new nom. is proposed as new name Turritella turris rotundata Schaffer 1912, non Turritella rotundata Grzybowski 1899. We designate lectotypes for Turritella gradata Menke in Hörnes, 1855, Haustator striatellatus Sacco, 1895, Allmonia carniolica (Stache, 1858) and Allmonia alterniplicata (Sacco, 1895). Neotypes are designated for Archimediella abundans (Handmann, 1882), Archimediella hoernesi (Rolle, 1856), Ptychidia partschi (Rolle, 1856), Ptychidia? ernesti (Handmann, 1882). Rhabdosis Townes, 1970 (Hymenoptera, Ichneumonidae) is a junior homonym of Rhabdosis Handmann 1882 (Gastropoda, Turritellidae) and will need a new name.

Neogene volcanism in Elazig-Tunceli area (eastern Anatolia): geochronological and petrological constraints

The Elazig and Tunceli provinces in eastern Anatolia host a complex succession of Miocene-Pleistocene effusive and explosive volcanic rocks, divided into four distinct volcanic phases. The most abundant and widespread products are the calcalkaline Mazgirt volcanic rocks, characterized by wide Sr isotope variations (87Sr/86Sr ~0.7054-0.7077) and narrower 143Nd/144Nd (~0.51246-0.51260) and Pb isotopes (e.g., 206Pb/204Pb ~18.89-19.13). New 40Ar-39Ar ages indicate that Mazgirt volcanic activity occurred between ~16.3 and 15.1 Ma. The other three volcanic phases are represented by the Tunceli mildly alkaline basaltic lavas (~11.4-11.0 Ma), the Pliocene Karakocan (~4.1 Ma) and Pleistocene Elazig (~1.9-1.6 Ma) Na-alkali basaltic lavas with clear OIB-like geochemical signature.Mazgirt volcanics can be subdivided on the base of mode of emplacement into lava flows and lava domes units characterized by petrographic, chemical and isotopic differences: lava flows are calcalkaline, whereas lava domes mostly belong to a high-K calcalkaline series and are, on average, more LREE- and 87Sr-enriched. Lava domes are more porphyritic, with a phenocryst assemblage dominated by amphibole, whereas plagioclase and clinopyroxene are the most abundant phenocryst phases in lava flows, pointing out that evolution of dome magmas occurred in conditions of slightly higher pressure, favouring the crystallization of hydrous phases.The Karabakir Formation, previously reported as late Miocene- Pliocene, encloses Mazgirt volcanics and is capped by Tunceli basalts. These new age data constrain the Karabakir Formation emplacement from early to late Miocene.The evolution of this igneous activity mirrors the geodynamic framework of the region: the early-middle Miocene Mazgirt volcanics represent arc volcanism related to Eurasia-Arabia convergence. The late Miocene Tunceli basalts postdate the onset of post-collisional tectonics in Eastern Anatolia, whereas the Karakocan and Elazig volcanic rocks were emplaced after the initiation of strike-slip motion on the North Anatolian and East Anatolian Fault systems.

Trichonis basin, western central Greece: is it an immature basin in the Corinth Rift or a pull-apart in a sinistral rift–trench link?

The 35 km long east–west-trending Trichonis basin in western central Greece is located between the Kephalonia Transform Fault and the east–west-trending Corinth Rift, exhibiting analogous, but smaller scale, morphotectonic features to the Corinth Rift. The final cooling and exhumation of the area started after at c. 10 Ma, after the burial owing to the emplacement of the Pindos thrust ( c. 30–20 Ma). The deformation includes (1) an Early–Middle Miocene transpression (T 1 ) during the waning stage of collision between Apulia and Eurasia, and (2) a Late Miocene–Pliocene radial extension (T 2 ), which relates to the separation of the Hellenic subduction zone from the Apulia (Adria)–Eurasia collision plate boundary through the Kephalonia Transform Fault. Two extensional stress tensors, T 3 and T 4 , with σ 3 in NNE (023°), and NNW (157°) directions, respectively, describe the modern stress regime in the Trichonis basin. This spatial stress partitioning is due to competition between back-arc stresses associated with Hellenic subduction-zone retreat and stresses of the post-collisional collapse of the Hellenic orogen. The Trichonis basin is not a pull-apart basin in a sinistral rift–trench link, but is an immature basin in the Corinth Rift along the Trichonis Fault. The later stands as a right-stepping fault branch to the main faults of the Corinth Rift.

New material of Gobicyon (Carnivora, Amphicyonidae, Haplocyoninae) from northern China and a review of Aktaucyonini evolution

AbstractThe aberrant carnivore Gobicyon has been known for more than 80 years, but the evolutionary position and taxonomic diversity of this animal remain unclear due to the paucity of the known fossils. Here, we report a much richer and better preserved assemblage of Gobicyon material from the Tongxin and Hezheng areas, northern China. Two new species, Gobicyon yei sp. nov. from the early middle Miocene in Tongxin and Gobicyon acutus sp. nov. from the late middle Miocene in Hezheng are recognized. Much better material of Gobicyon macrognathus and one isolated tooth of Gobicyon zhegalloi from Tongxin are also described in detail. Gobicyon is recognized as a derived haplocyonid. A phylogenetic analysis of Gobicyon and related taxa has been performed for the first time. The phylogenetic tree suggests a close relationship of Aktaucyon and Gobicyon (Aktaucyonini). Among the taxa traditionally included in haplocyonids, Haplocyonopsis is the closest to Aktaucyonini, as supported by its centrally located M1 protocone and a uniformly distributed M1 lingual cingulum. The most significant evolutionary trends of Gobicyon are the reduction of the posterior molars (M2 and M3) and the strengthening of P4 and M1, suggesting a forward shift of crushing function along the tooth row.

The first fossil barbet (Aves, Ramphastidae) from Siberia

Barbets are arboreal birds, inhabiting mainly tropical forests west of the Wallace’s Line. Fossil remains of barbets are extremely scarce. Until recently, only two species of barbets were described from the early and middle Miocene of Europe and several other undescribed fragments were mentioned in the literature. Here I report the first finds of barbets from Eastern Siberia. ?Capitonides sp. is here described from the late early Miocene of Baikal Lake based on a distal part of the humerus, an omal part of the coracoid, and a distal part of the ulna. The morphology of the fossil specimen does not allow attributing it to any of the modern genera, and thus ?Capitonides sp. is apparently a stem representative of the group. This find documents a previously unrecognized broad geographical distribution of barbets during the warmest phase (climatic optimum) of the Miocene. The observed similarity between the early–middle Miocene arboreal avifaunas of Western Europe and Eastern Siberia suggests the presence of a wide belt of relatively humid forests connecting Europe and Asia.

Effect of burial history on diagenetic and reservoir-forming process of the Oligocene sandstone in Xihu sag, East China Sea Basin

Abstract Porosity evolution history, hydrocarbon charging periods, diagenetic and reservoir-forming characteristics of low-permeability and tight sandstone are presented in this study. The interpretation is based on information including thin section, scanning electron microscope, homogenization temperature of fluid inclusion, bulk rock X-ray diffraction analysis, clay X-ray diffraction analysis and stable isotopic composition. These sandstones are located in the Oligocene E3h Formation in the Xihu sag, East China Sea Basin, East China. Five diagenetic events in the H3, H4 and H5 members were determined, including connate alkaline pore water of the Oligocene sandstone, meteoric water leaching in late Miocene, organic acids and CO2 acidic fluids in early-middle Miocene, reservoir temperature decrease induced by tectonic uplift, and alkaline diagenetic environment from late Miocene to present day. Porosity evolution history of different grain-size lithology were evaluated by basin modelling and test data. The medium sandstone and coarse sandstone of the H3 member and medium sandstone of the H4 member not reached the tight state in the geologic time. The fine sandstone of the H4 member entered the tight state at 12 Ma, suffered acidic fluids to improve the tight state in late stage, and entered the tight state again since 6.5 Ma. The medium sandstone, fine sandstone and siltstone in the H5 member entered the tight state at 13.5Ma, 16Ma and 19Ma, respectively. Three hydrocarbon charging periods were determined, including 15.5 Ma-10.4 Ma in the middle Miocene, 9.6 Ma-7.0 Ma in the late Miocene and 6.2 Ma-0.0 Ma from the late Miocene to present day. Three diagenetic and reservoir-forming patterns were proposed, including accumulation without tightness, accumulation after tightness-improving reservoir quality with acidic fluid-accumulation while tightness, accumulation after tightness. The burial history cannot be ignored in the diagenetic events, porosity evolution history and hydrocarbon charging periods of similar low-permeability and tight sandstone in sedimentary basins.

Phylogeny, origin and dispersal of Saussurea (Asteraceae) based on chloroplast genome data

Saussurea is one of the largest genera of the tribe Cardueae of Asteraceae, comprising about 460 species from the Northern Hemisphere with most species distributed in QTPss and adjacent areas. Here, we established a well-supported phylogenetic framework for Saussurea based on whole chloroplast genomes of 136 taxa plus 16 additional taxa of Cardueae using Bayesian inference and Maximum Likelihood. Our phylogenetic results are inconsistent with previous subgeneric classifications of Saussurea. We nearly completely delimited subgen. Eriocoryne, and found that subgen. Theodorea, subgen. Saussurea section Laguranthera and Rosulascentes are closely related to each other. Based on our phylogenetic results, we performed biogeographic analyses and inferred that the genus Saussurea arose during early-middle Miocene within the Hengduan Mountains. We expect that landscape heterogeneity within the QTPss and adjacent areas, such as the Hengduan Mountains, played an important role in the evolution of Saussurea. Following its evolutionary origin, the genus underwent rapid diversification in situs and dispersed northwards in several migrational patterns. Both continuous uplift of the QTPss and adjacent areas as well as global cooling since mid-Miocene probably led to geographic expansion and diffusion of Saussurea, with the latter, in particular, resulting in the northward dispersal.