Search

Reconstructing the origin and historical biogeography of the Austropotamobius torrentium is hampered by insufficient phylogeographic coverage of the Balkans and deep contradictions in previous molecular dating. The present work extends the phylogeographic coverage to Serbia, a country crucial for understanding the species southward dispersal. Our analysis revealed that the Southern Balkans lineage occurs in most of the country, the Central and southeastern Europe lineage is restricted to the southwest and northeast of the country, while a single population in the north of the country harbors the Lika and Dalmatia lineage, which was previously thought to be restricted to the northern-central Dinarides. Dataset expansion led to revised phylogenetic relationships, which indicated that the Apuseni lineage is not nested within Northern-central Dinarides lineages but arose after the most basal split within Austropotamobius torrentium. This 'Apuseni first' phylogeny provides a new perspective for molecular dating, according to which the split between Austropotamobius pallipes and A. torrentium took place in the Late Oligocene, while the formation of the phyletic lineages and the dispersal from the Dinarides to Serbia occurred in the late Miocene and is probably associated with the complex and protracted process of disintegration of the Neogene freshwater lakes in southeastern Europe. [ABSTRACT FROM AUTHOR]

ABSTRACT This response addresses the comments made by Saraswati et al. on our recent publication in Geological Journal. In our study, we used a multi‐analytical screening approach, including visual, XRD and trace element analysis, to evaluate diagenetic alteration of carbonate shell samples. Contrary to the claims made by Saraswati et al. our findings are based on well‐preserved samples with minimal alteration. The Sr‐isotope data from the Khari Nadi Formation (23.07–18.09 Ma) are largely consistent with existing biostratigraphic constraints, but suggest a possible extension of the upper age limit into the Burdigalian. Our Sr‐isotope ages for the Chhasra Formation (15.11–12.29 Ma) are younger than those suggested previously, based on larger benthic foraminifers, but largely corroborate recent nannoplankton data. As a result of the new age data from Kutch, we suggest that the sedimentation rates, derived from multiple samples, increased significantly from the Oligocene to Miocene. We assert that ‘established’ ages are also subject to refinements as the rock units become amenable to new dating techniques. We welcome any criticism that is constructive, and remain open to any further data that could refine or challenge our interpretations. [ABSTRACT FROM AUTHOR]

Deciduous dentition of extinct mammals has traditionally received little attention based on its poor representation in the fossil record. However, several aspects related to this tooth locus could have important evolutionary significance (time of replacement, retention throughout life, and morphology). In this work, we described a new specimen from late Oligocene levels of Cabeza Blanca (Chubut Province, Argentina). This fossil corresponds to a maxillary fragment with a deciduous premolar (DP4) assigned herein to Cephalomys arcidens based on morphological characteristics, size, and comparisons with other late Oligocene-Early Miocene caviomorphs. It can be identified as a DP4 due to its mesiodistally longer than wide diameter, shallow flexi, complex tooth morphology, and its position in the maxillary fragment. This is the first description of the DP4 of a Cephalomyidae and the last unknown dental locus of Cephalomys arcidens. Now, C. arcidens is one of the better-known late Oligocene caviomorphs since it is recognised through the complete dentition, crania, and mandibles. In addition, this new information would be used to evaluate the importance of deciduous dentition in resolving phylogenetic relationships in the enigmatic cephalomyids in particular and in Caviomorpha in general. [ABSTRACT FROM AUTHOR]

As a passive rift basin in the Cenozoic, the formation and evolution process of the Weihe Basin has not been well explained. Here we estimate the stretching factor and basal heat flow for each rift period along four geological profiles using a 2D multi-stage finite extension model. The modelling is based on a reconstruction of pre-rift crustal and lithospheric thicknesses, and is calibrated with the current heat flow. The Xi'an Depression had the biggest stretching factor while the Pucheng Uplift had the smallest throughout the Cenozoic period, which saw a range of stretching factors from 1.02 to 2.06. The basal heat flow in the Weihe Basin exhibits a corresponding change. At the end of the Oligocene, Miocene, and Pliocene periods, the basal heat flow varied between 58.5 ~ 64.0 mW·m−2, 59.2 ~ 67.0 mW·m−2, and 59.6 ~ 78.7 mW·m−2, respectively. Increasing stretching factor and basal heat flow indicate that the Weihe Basin is currently in a state of sustained extension. The formation and development of the Weihe Basin are analysed in the context of larger tectonic changes, and it is considered that the Weihe Basin is controlled by pre-existing faults, and formed in a regional tectonic context of sliding and pulling apart first, and tensioning and lifting up later. Since the late Miocene (7.3 Ma), anomalously rapid subsidence has occurred, induced by a new phase of rifting and depth-related lithospheric extension. The thermal genesis of the geothermal system in the Weihe Basin is also thought to be closely related to the latest phase of extension. [ABSTRACT FROM AUTHOR]

Gobioid fishes (Teleostei) are renowned for their remarkable species diversity in marine and freshwater environments, making their evolutionary history a fascinating study subject. Among their oldest known fossils is the small-sized freshwater goby ‘Gobius’ gracilis from the Lower Oligocene of Central Europe, which has not undergone a detailed investigation since its first description. Here, we present a comprehensive re-analysis of ‘G.’ gracilis using type specimens and new material from museum collections. We show that this species possesses a unique combination of traits, leading to the establishment of a new genus, †Laubeichthys gen. nov. Phylogenetic analyses using Bayesian Inference (BI) recover †Laubeichthys gen. nov. as a stem member of the extinct family †Pirskeniidae and suggest a sister relationship between the family Thalasseleotrididae (ocean sleepers) and †Laubeichthys gen. nov. + †Pirskeniidae. Maximum parsimony analyses do not contradict such a relationship, but the trees are less resolved. Today, the Thalasseleotrididae includes four marine species that are restricted to the Southwest Pacific. In contrast, †Pirskeniidae and †Laubeichthys gen. nov. inhabited freshwater environments in Central Europe. Our findings provide new insights into the evolutionary history and historical biogeography of gobioid fishes and highlight the dynamic nature of their past diversity and distribution. [ABSTRACT FROM AUTHOR]

Changbaishan volcano (CBV), located on the border between China and North Korea, has undergone violent eruptions since the Oligocene, making it one of the most captivating and explosive volcanoes on Earth. However, the lack of precise characterization regarding the magmatic system makes it difficult to decipher its eruption risk and mechanism, despite its significant size and past devastating effects. In this study, we employed newly developed teleseismic receiver function techniques, including Ps and Sp waves, to construct a lithospheric structure model beneath the CBV region. The results show a thick crust (~37 km) and a weak, thin lithosphere under the CBV, with a low-amplitude width of 80 km at the Moho depth and 200 km at the depth of the lithosphere-asthenosphere boundary. These features depict the seismological response of a translithospheric magmatic system beneath the CBV, where hot upwelling material rises through the lithospheric mantle, underplates at the base of the crust, and forms the magma chamber(s) at shallow depth. Such magmatic system features can be taken as a unifying paradigm for large volcanic regions worldwide. [ABSTRACT FROM AUTHOR]

Premise: Molecular studies based on chloroplast markers have questioned the monophyly of the fern genus Pecluma (Polypodioideae, Polypodiaceae), which has several species of Polypodium nested within it. We explored the delimitation of Pecluma and its biogeographic pattern by evaluating the phylogenetic position of four Polypodium species not sequenced thus far and integrating the first fossil evidence of Pecluma. Methods: Using herbarium material, we applied a genome‐skimming approach to obtain a phylogenetic hypothesis of Polypodioideae; assessed the combination of character states observed in the fossil from Miocene Dominican amber using a previously published phylogeny of Polypodioideae based on four plastid markers as framework; calculated divergence times; and conducted an ancestral area estimation. Results: Within Polypodioideae, Pecluma was recovered as sister to Phlebodium. Three of the newly sequenced species—Polypodium otites, P. pinnatissimum, and P. ursipes—were recovered with maximum support within the Pecluma clade, whereas P. christensenii remained within Polypodium. The closest combination of character states of the fossil was found within Pecluma. Our biogeographic analyses suggest an Eocene origin of the genus in South America, with several subsequent Oligocene and Miocene colonization events to Mexico–Central America and to the West Indies. Conclusions: Although the circumscription of Pecluma is still challenging, our results elucidate the origin and age of the genus. The newly described fossil, Pecluma hispaniolae sp. nov., supports the hypothesis that the epiphytic communities of the Greater Antilles exhibit a constant generic composition since the Miocene. We propose new combinations (Pecluma otites, Pecluma pinnatissima, and Pecluma ursipes) to accommodate three species previously classified in Polypodium. [ABSTRACT FROM AUTHOR]

The palynological analysis of the Paleogene and Neogene sequences of the southern part of West Siberia (borehole 2, Novosibirsk oblast) showed that the conifer bisaccate pollen in the spore–pollen spectra exhibits a series of morphological features allowing its comparison with the modern pollen of Cathaya argyrophylla Chun et Kuang. These palynomorphs belong to relict vegetation, which currently occurs in the wet subtropical climate of South China, and are important climate indicators. The palynomorphs are ascribed to the ancestral forms of the species Cathaya as Abietineaepollenites sellowiiformis (Zaklinskaja) Doweld 2018. The pollen is described, and its distribution along the section is shown. The maximum amount of the A. sellowiiformis pollen (up to 23.7%) is confined to the upper part of the Oligocene and the Lower Miocene and its last appearance is recognized in the Middle–Upper Miocene. These data expand our knowledge on the geographic range of the Cathaya ancestral form and its role in plant communities of Central Asia in the Cenozoic. [ABSTRACT FROM AUTHOR]

The northwestern part of the Sevan–Shirak structural formation zone of the Lesser Caucasus contains ultra-high-K siliceous ignimbrites dating back to the Late Eocene–start of Early Oligocene (?), which associate with high-K volcanics of the calc-alkaline and shoshonite series. During Eocene–Oligocene time the Sevan–Shirak zone was an ensialic island arc with a Hercynian metamorphic basement. The formation of high-K and especially ultra-high-K rocks was due to the effects of mantle fluids on the continental crust. [ABSTRACT FROM AUTHOR]

Within the territory of Primorye, regional boundaries between the high-rank stratigraphic subdivisions were discussed, including the boundaries between the Cretaceous and Paleogene, Paleogene and Neogene, and Neogene and Quaternary systems, as well as the boundaries between series within the systems. The following boundaries can be considered as the most valid and suitable as stratotypes: the Eocene, Oligocene boundary, attributed to the transition from the coal-bearing Khasanskaya Formation to the coal-free tuff siltstone Fatashinskaya Formation (Khasan Basin); the Paleogene, Neogene boundary, marked by the change in the lithological type of rocks from coal-bearing Upper Oligocene sediments to tuff siltstones and tuffs that make up the base of the Miocene (Rakovka Basin). It is proposed that the Miocene, Pliocene boundary be drawn within the basaltic lava complex with sedimentary rock members forming the Shufan and Shkotov volcanic plateau at the base of the Kedrovskaya sequence. The proposed Pliocene, Quaternary boundary corresponds to the base of the red-colored "pudding" sequence (Spassk Basin). The Cretaceous, Paleogene and Paleocene, Eocene boundaries cannot be determined with acceptable accuracy due to the lack of corresponding sections in the region. [ABSTRACT FROM AUTHOR]

Pre-Miocene, stem odontocetes are known for their procumbent incisors and their function has been the subject of much speculation. Notable among these were Waipatia and several related taxa from New Zealand. Though some studies hypothesise the function of these teeth was for thrusting, the here described Aureia rerehua has unique teeth which might have formed a cage around small fish. These teeth, along with a weak vertex, flexible neck, and the smallest size among its relatives would make it a capable hunter in shallow waters. The addition of A. rerehua along with other taxa to phylogenetic analyses show three broad groups within taxa related to Waipatia and Otekaikea based on the divergence of the function of their teeth and the possible feeding strategies employed to catch prey. [ABSTRACT FROM AUTHOR]

The Kekenodontidae are late-surviving archaeocetes from the Late Oligocene of Southwest Pacific that includes a single-named species, Kekenodon onamata. Tohoraonepu nihokaiwaiu is a new genus and species of small body-sized kekenodontid from the upper Oligocene (Chattian) Kokoamu Greensand of Otago, South Island, New Zealand. Phylogenetic analyses recover T. nihokaiwaiu within a monophyletic Kekenodontidae, forming a clade with an unnamed provisional kekenodontid, OU 22023. Kekenodontids are recovered crownward to basilosaurids and stemward to a paraphyletic group of toothed 'mysticetes' that are excluded from Neoceti. The analyses confirm the identification of kekenodontids as the latest-diverging archaeocetes that persisted into the Late Oligocene. The holotype OU 22394 is a juvenile individual preserving several isolated heterodont teeth with characteristics of deciduous teeth, including unmineralized pulp cavities and cheek teeth with lower-lying triangular crowns that are different from all known kekenodontids. Diphyodonty is known from Eocene archaeocetes but is unknown from geologically younger toothed cetaceans, with monophyodonty being hypothesised for all Neoceti. Inferences of diphyodonty in T. nihokaiwaiu would be the first instance in Cetacea from rocks geologically younger than the Eocene and would indicate diphyodonty persisted in some Late Oligocene archaeocetes. [ABSTRACT FROM AUTHOR]

Eomysticetidae are a clade of early diverging functionally toothless, longirostrine and likely baleen-bearing stem mysticete whales. Eomysticetid fossils are rare but known worldwide from Oligocene strata. The richest assemblage of eomysticetids has been uncovered in New Zealand from the Kokoamu Greensand and Otekaike Limestone (North Otago and South Canterbury regions, South Island). This includes some of the largest known eomysticetids, Tokarahia kauaeroa and Tokarahia lophocephalus, some older and more archaic forms such as Matapanui waihao, the fragmentary Tohoraata raekohao and Tohoraata waitakiensis, and the well-known Waharoa ruwhenua represented by several well-preserved skulls and mandibles of adults and juveniles. Studies of these New Zealand fossils strongly indicates monophyly of Eomysticetidae and suggest possible skim feeding behaviour, possession of non-functional teeth and baleen, extreme rostral lengthening during growth and peramorphic evolution, rostral kinesis, use of Zealandia as a calving ground, and probable extinction at or near the Oligo-Miocene boundary. [ABSTRACT FROM AUTHOR]

Recent research on mysticete fossils from the Late Eocene and Oligocene has revolutionised our understanding of the diversity and evolutionary scenarios for early baleen whales. For example, aetiocetids are a possible, though controversial, lineage that bridges the gap between the toothed and baleen-bearing mysticetes, and eomysticetids show a further transitional step towards the baleen-bearing status, with the presence of non-functional dentition in adults. However, information about the origin of crown mysticetes, including the most recent common ancestor of all extant lineages and its descendants, is critical to further understanding the evolution of baleen whales. The phylogenetic positions of the Oligocene Toipahautea, Whakakai, Horopeta, and Mauicetus from New Zealand remain unresolved and problematic, but all four genera show a close relationship with crown mysticetes. The original and subsequent cladistic analyses have consistently revealed a sister relationship between the Toipahautea-to-Mauicetus grade and crown mysticetes, and Horopeta has been placed close to the cetotheriids within the crown group. This review aims to stimulate more research on this topic by elucidating the origin of crown mysticetes, which likely experienced a poorly known radiation event during the Oligocene that established the modern lineages. [ABSTRACT FROM AUTHOR]

Kekenodontids are the only known archaeocetes (stem cetaceans) from the late Oligocene. They possess a unique combination of morphological features seen in both more primitive Eocene basilosaurid archaeocetes and more derived Neoceti (mysticetes and odontocetes). However, much remains unknown about the clade, including its acoustic biology. Based on its phylogenetic position crownward to basilosaurids as the latest‐diverging archaeocete, we hypothesize that kekenodontids would be specialized for hearing low‐frequency sounds. Here, we provide the first report on the cochlear anatomy of a kekenodontid using the holotype of Kekenodon onamata from New Zealand. We compare the cochlear morphology of K. onamata to a sample of extinct and extant cetaceans and quantify shape differences using three‐dimensional geometric morphometrics. The analyses show that K. onamata was indeed adapted to hear low frequencies and suggests low‐frequency hearing may be a characteristic of raptorial macrophagous fossil cetaceans in contrast to infrasonic bulk filter‐feeding mysticetes and ultrasonic echolocating odontocetes. [ABSTRACT FROM AUTHOR]

A long‐standing question in evolutionary biology is how historical biogeographic processes have shaped the current diversity of organisms, especially for highly diverse groups. We study the diversification dynamics and biogeographic processes of one of the most diverse families of Lepidoptera, Geometridae, with over 24,000 described species and a worldwide distribution. Despite the cosmopolitan distribution of the family, most species of Geometridae have limited distribution ranges. We present the largest historical biogeography and diversification study on the current diversity patterns and distribution ranges of Geometridae. We use a multi‐locus dataset of 1200 taxa to estimate the historical biogeography of Geometridae, implementing a Bayesian approach of the Dispersal‐Extinction‐Cladogenesis (DEC) model that incorporates palaeographic‐based dispersal graphs with uncertainty in geological ages in RevBayes. We also implement a Bayesian time‐variable, episodic birth–death model and a model that allows branch‐specific speciation rates to estimate the diversification dynamics in the family. Our results suggest that the most recent common ancestor of Geometridae was distributed in the New World, with the Neotropics being the most likely ancestral area. An increase in diversification rates occurred circa 30–40 million years ago (Mya), coinciding with a time of a major global climate cooling in the Eocene. Clade‐specific shifts in speciation rates also occurred around 10–15 Mya, coincident with another period of major climate change in the Oligocene. Our results point to different biogeographical and evolutionary histories per area to show the differences of the diversification rates in different biogeographical regions through time, showing the relative importance of each region in the diversification history of Geometridae. [ABSTRACT FROM AUTHOR]

ABSTRACT Despite a growing interest, few studies integrate quantitative supercritical‐flow deposit (SFD) distribution into paleoenvironmental reconstructions in deep‐marine settings. We present a re‐evaluation of the Oligocene Annot Sandstones (SE France) in terms of flow criticality, by examining the spatial distribution of SFDs. Proximal settings exhibit SFD proportion varying from ~90% to 40% with a common occurrence of cyclic steps, whereas distal environments show <40% SFDs with antidunes and upper‐plane beds prevalent. Comparing SFD spatial distribution to other proxies in the Annot Sandstones and published proxies from the Eocene Ainsa‐Jaca basins (Spanish Pyrenees), SFD trends appear more consistent than those in sandstone percentages, or the distribution of the Bouma sequence divisions. Our approach achieves two goals: (1) establishing the reliability of quantitatively analysing SFDs as a proxy for paleoenvironment reconstructions, characterising the proximal‐to‐basin floor transition at ~40% SFDs and (2) providing fundamental insights into the formation processes compared to other proxies. [ABSTRACT FROM AUTHOR]

Background: Endemic plants are key to understanding the evolutionary history and enhancing biodiversity within their unique regions, while also offering significant economic potential. The East Asian endemic genus Corchoropsis Siebold & Zucc., classified within the subfamily Dombeyoideae of Malvaceae s.l., comprises three species. Results: This study characterizes the complete plastid genomes (plastomes) of C. crenata var. crenata Siebold & Zucc. and C. crenata var. hupehensis Pamp., which range from 160,093 to 160,724 bp. These genomes contain 78 plastid protein-coding genes, 30 tRNA, and four rRNA, except for one pseudogene, infA. A total of 316 molecular diagnostic characters (MDCs) specific to Corchoropsis were identified. In addition, 91 to 92 simple sequence repeats (SSRs) in C. crenata var. crenata and 75 in C. crenata var. hupehensis were found. Moreover, 49 long repeats were identified in both the Chinese C. crenata var. crenata and C. crenata var. hupehensis, while 52 were found in the South Korean C. crenata var. crenata. Our phylogenetic analyses, based on 78 plastid protein-coding genes, reveal nine subfamilies within the Malvaceae s.l. with high support values and confirm Corchoropsis as a member of Dombeyoideae. Molecular dating suggests that Corchoropsis originated in the Oligocene, and diverged during the Miocene, influenced by the climate shift at the Eocene–Oligocene boundary. Conclusions: The research explores the evolutionary relationships between nine subfamilies within the Malvaceae s.l. family, specifically identifying the position of the Corchoropsis in the Dombeyoideae. Utilizing plastome sequences and fossil data, the study establishes that Corchoropsis first appeared during the Eocene and experienced further evolutionary divergence during the Miocene, paralleling the evolutionary patterns observed in other East Asian endemic species. [ABSTRACT FROM AUTHOR]

Gymnophthalmids are a diverse lineage of Neotropical lizards that present challenges in the understanding of their phylogenetic relationships and biogeographic history. Using a densely sampled phylogeny and distribution data, we investigated their biogeography at the family level. Dividing South and Central America into 12 regions, we tested six biogeographic models considering dispersal-extinction, vicariance, and founder events. Our analysis revealed high taxonomic and phylogenetic endemism in the Andes, Amazon, and Guiana Shield. The best-fit model identified the Guiana Shield as the likely ancestral area of the family, with dispersal events dominating over vicariance. Key areas for species interchange were the Amazon, Northern Andes, and Guiana Shield. The core regions of diversification included the Andes, Amazon, and Guiana Shield, with elevated species richness and biotic interchange events during the Eocene and Oligocene. The Guiana Shield stood out as a stronghold of gymnophthalmid diversity, driven by dispersal rates and ancient lineages. Our findings challenge previous hypotheses about the diversification of these lizards, suggesting a colonization pattern from lowlands to high elevations rather than the South-to-North Speciation Hypothesis for Andean lineages. [ABSTRACT FROM AUTHOR]

Wing venation pattern is particularly important in the taxonomy and classification of insects, especially for fossil material. There are recognized transformation series that apparently often represent a mainstream in the evolutionary trend of the wing venation of Hymenoptera. One notable instance is the gradual reduction of the subcosta veins from multiple branches to their total absence. Herein, we place four new genera and six new species in the family Blasticotomidae (=Xyelotomidae) of Hymenoptera. They are Xyelocerus abruptus sp. nov. Liberitoma tenella gen et sp. nov. Liberitoma compta sp. nov. Liberitoma incompleta sp. nov. Aduantoma insolita gen. et sp. nov. and Apertoma gen. nov. from the Middle Jurassic of China, and Enspeletoma oligocaenica gen. et sp. nov. from the Upper Oligocene of Germany. The newly discovered species of Liberitoma from China possessed a supernumerary hind branch of vein Sc in its forewing, which has apparently never been recorded before in other hymenopterans, and the unique venation pattern of Aduantoma suggests the possibility of two additional steps of vein Sc transformation before its complete loss. Based on the new findings, Blasticotomidae are proposed to be divided into four subfamilies: Blasticotominae Thomson 1871, Dahurotominae subfam. nov. Pseudoxyelocerinae subfam. nov. and Undatominae subfam. nov. [ABSTRACT FROM AUTHOR]

Isolation of desert springs often leads to the evolution of unique biodiversity. We investigated the taxonomy and evolutionary relationships of members of the Gammarus pecos complex, an assemblage of narrowly endemic amphipod species in the Chihuahuan Desert of the USA. Morphological and molecular phylogenetic analyses, including newly obtained COI sequences from the now-extinct type population of Gammarus desperatus , reveal the presence of two undescribed species and lead to redescription of G. desperatus. Gammarus acerbatus sp. nov. is split from G. desperatus and Gammarus balmorhea sp. nov. is split from G. hyalelloides. Each of these species is endemic to a single spring system. Speciation in the Gammarus pecos complex was likely promoted by the lineage's ties to marine/riverine systems and geological events during the Oligocene/Miocene. The additional diversity discovered within the complex highlights the effects of both habitat and evolutionary history on the processes of speciation at local and regional spatial scales. The entire complex of at least six species is imperilled due to the narrow ranges occupied by each species and human water-use that threatens the existence of their spring habitats. [ABSTRACT FROM AUTHOR]

The manganese deposits at the Kato Nevrokopi area are located in the Drama Basin (Northern Greece) and belong to the Rhodope Metamorphic Province. The deposits were previously exploited for several supergene Mn-oxide ore bodies of massive, battery-grade nsutite, spatially associated with fault zones in the vicinity of Oligocene granitic intrusions. We conducted detailed geological, mineralogical, and geochemical investigations at the Mavro Xylo deposit, which led to the identification of Ag-rich Mn-Zn±Pb vein-type mineralization. The studied paragenesis appears to have developed during two hydrothermal stages: stage I, characterized by the mineral assemblage rhodonite–quartz–rhodochrosite–pyrophanite–pyrite–galena–Te bearing argentite–sphalerite–wurtzite–alabandite, and stage II, dominated by Ag-rich, Mn-Zn±Pb oxides in the form of fracture-fills along a high-angle NE-SW fault zone in brecciated marbles. Bulk analyses of the stage-II oxide assemblage yielded concentrations of Ag up to 0.57 wt.%. In the veins, wurtzite is present in bands, succeeded by manganese oxides, while calcite and quartz are the main gangue minerals. We placed particular emphasis on the occurrence of Ag in high concentrations within distinct manganese oxides. Major silver carriers include Zn-bearing todorokite, chalcophanite, and hydrous Pb-Mn oxide. The vein-type mineralization at Mavro Xylo shares many characteristics with other intermediate-sulfidation epithermal precious metal-rich deposits associated with high Mn concentrations. The evolution of the mineral paragenesis indicates a change in the physicochemical attributes of the ore-forming fluids, from initially reducing (stage I) to oxidizing (stage II). Although the origin of the initial ore-forming fluid remains to be constrained, the above redox change is tentatively attributed to the increasing incursion of meteoric waters over time. [ABSTRACT FROM AUTHOR]

The surface and subsurface karst features of the Eocene limestone plateaus along the Middle Nile Valley in Egypt were formerly believed to be epigene in origin and to have developed during post-Eocene pluvial periods. However, the morphology of the caves and their restriction to particular stratigraphic intervals suggests that they are hypogene. The geochemistry and mineralogy of the soft, thick-bedded, brown/black cave infills shows that these sediments originated from hydrothermal processes, as evidenced by their Fe, Mn, Co, Ni, and Cu concentrations. Thus, the karst features are hypogene and probably formed during the opening of the Red Sea Rift at the end of the Oligocene and early Miocene. At this time, there was abundant volcanic activity, as shown by basalt lavas ~70 km northwest of Assiut; this triggered the release of large amounts of CO2 that made the hydrothermal waters acidic and dissolved the caves. [ABSTRACT FROM AUTHOR]

The Eocene-Oligocene transition (EOT) marked a rapid global cooling event, often considered as the beginning of the modern icehouse world. Influenced by various factors, including tectonic activity and paleogeographic settings, the terrestrial records indicate a diverse response of fauna and vegetation to this global event. We examined nine macrofossil assemblages from seven fossil localities on the southeastern margin of the Tibetan Plateau and from the mid-latitudinal Europe ranging from the latest Bartonian and Priabonian (37.71–33.9 Ma) to the Rupelian (33.9–27.82 Ma). Our aims were to trace and compare the vegetation history of both regions in the late Eocene and early Oligocene. The results show that both regions experienced changes in vegetation composition in response to climate change, characterized by a decrease in the percentages of broad-leaved evergreen elements and distinctive changes in general vegetation types. A general change in the overall vegetation type from subtropical broad-leaved evergreen forests in the late Eocene to temperate broad-leaved mixed deciduous evergreen forests, or mixed mesophytic forests, in the early Oligocene is recognized in both regions. The results indicate a clear change in leaf architecture, leaf margin states, and secondary venation types in the mid-latitudinal Europe, while the results from the south-eastern margin of the Tibetan Plateau show a distinct reduction in leaf size. Our data suggest that both global and regional factors played key roles in shaping the vegetation in the two regions. [ABSTRACT FROM AUTHOR]

A deep-marine sedimentary succession of Whaingaroan to Altonian age (Early Oligocene–Early Miocene), cropping out near Weber, southern Hawke's Bay, records abrupt changes in depositional paleoenvironments and sedimentary lithofacies. Highly calcareous early Waitakian (latest Oligocene) Weber Formation (Mangatu Group/Waka Supergroup) is unconformably overlain by terrigenous-dominated late Waitakian–Otaian (Early Miocene) Coast Road or Whakataki formations (Tolaga Group/Māui Supergroup). Most notably, in some localities, lowermost parts of the Coast Road Formation (Mangapuku Mudstone Member) contain prominent matrix-supported extra-formational olistoliths of centimetre to decametre scale derived from the underlying Weber Formation. Deposition of these blocks is attributed to deep-water collapse of parts of rapidly growing, over-steepened, reverse-fault-controlled thrust ridge(s). The onset of Coast Road and Whakataki formation deposition and associated abrupt changes in sedimentary lithofacies correlate to prominent Early Miocene lithological, mineralogical, and paleoenvironmental changes elsewhere along the Hikurangi Margin. We attribute these bio- and lithostratigraphic changes as evidence for significant shortening and upper-plate reverse faulting marking the onset of subduction beneath eastern North Island during the mid-Waitakian (c. 23 Ma). Proposed lithostratigraphic revisions presented herein help clarify depositional events and correlative sedimentary packages within the Miocene Hikurangi margin. [ABSTRACT FROM AUTHOR]

The southern Central Andes (∼25–40°S) exhibit a complex tectonic history, crucial for understanding orogenic processes in subduction-related orogens, yet debate on the timing and mechanisms of early Cenozoic topographic growth persists. We present double-dated detrital zircon U-Pb and (U-Th)/He thermochronology data from the early Oligocene–Miocene Bermejo Basin at ∼30°S to investigate source unroofing during development of the High Andes. (U-Th)/He results yield dates of ca. 565–16 Ma (n = 73), with distinct detrital modes that indicate a mixing of sediment sources characterized by variable cooling and exhumation histories. We employ a novel approach for modeling detrital thermochronology data that leverages the shared basin subsidence history of multiple detrital modes to resolve provenance and source unroofing histories. Results from the lower Oligocene Vallecito Formation (northwestern Argentina) reveal that detritus was sourced from Permian–Triassic Choiyoi Group rocks that underwent rapid late Eocene cooling, indicated by short lag time (2–5 m.y.) between source cooling and deposition. Our findings are consistent with bedrock studies of Eocene exhumation in the High Andes and establish source-to-basin connectivity during this time. Other detrital modes with pre-Cenozoic cooling histories were derived from Carboniferous Elqui-Colangüil and Choiyoi Group rocks or recycled from Paleozoic basins. We propose that an early Oligocene drainage divide in the High Andes was located west of the Punilla–La Plata fault, an active thrust front at ∼30°S. These findings challenge Paleogene neutral stress-state models for the Andes and underscore the importance of improved knowledge of erosion and deformation histories for refining models of Andean orogenesis. [ABSTRACT FROM AUTHOR]

We describe a new species of the fossil perciform genus Dapalis (Ambassidae), Dapalis pauciserratus n. sp., based on two articulated skeletons with otoliths in situ from the lower Oligocene of Raljin/Strelac, Babušnica basin, Southern Serbia. This species differs from congeners in the combination of following characters: (i) body elongate, fusiform; (ii) head triangular in shape; (iii) supraoccipital crest distinct; (iv) head without serrations except two large spine-like serrations on the corner of the preopercle; (v) premaxilla with a relatively narrow postmaxillary process located in the distal half; (vi) spines of the first and second dorsal fins, the anal fin and the pelvic fin strong but not massive; (vii) first spine of first dorsal fin long (42% of length of second spine); (viii) otoliths elongate (length/height = 1.4) with a narrow and elongate ostium, indistinct antirostrum, shallow excisura and an asymmetric and prominent rostrum. [ABSTRACT FROM AUTHOR]

We report herein the fossil record of lissamphibians unearthed from the late Eocene – early Oligocene localities of the north-western side of the Transylvanian Basin. Among the late Eocene (Priabonian) fossil vertebrate sites, the Bociu locality yielded discoglossid and pelobatid frogs, while the Treznea locality yielded a moderately diverse assemblage of discoglossid (Latonia sp.), palaeobatrachid, pelobatid and ranid (Pelophylax sp.) frogs. The assemblages derived from the early Oligocene (Rupelian) fossil localities of Suceag 1 and Cetățuia Hill, Cluj-Napoca include salamandroid newts (Mioproteus gardneri), discoglossid (Latonia sp.), palaeobatrachid (Albionbatrachus oligocenicus) and ranid frogs (Pelophylax sp.). Disparity between the contemporaneous anuran assemblages from the Transylvanian Basin and those representing the more diverse cratonic Europe is derived mainly from the persisting insular conditions of the studied area. The drop of mean annual temperature in northern Europe and the enlarging freshwater corridors may have facilitated the southeastern distribution of highly aquatic amphibian groups like the proteid salamander Mioproteus, the ranid frog Pelophylax and the palaeobatrachid frog Albionbatrachus, the latter being considered a late Eocene survivor, recorded previously from the western part of the continent. [ABSTRACT FROM AUTHOR]

The dramatic decrease in atmospheric CO2 concentration during Oligocene was proposed as directly linked to C4 evolution. However, it remains unclear how the decreased CO2 concentration directly facilitate C4 evolution, besides its role as a selection pressure. We conducted a systematic transcriptomics and metabolomics analysis under short-term low CO2 condition and found that Arabidopsis grown under this condition showed 1) increased expression of most genes encoding C4-related enzymes and transporters; 2) increased expression of genes involved in photorespiration and pathways related to carbon skeleton generation for ammonium refixation; 3) increased expression of genes directly involved in ammonium refixation. Furthermore, we found that in vitro treatment of leaves with NH4 + induced a similar pattern of changes in C4 related genes and genes involved in ammonium refixation. These data support the view that Arabidopsis grown under short-term low CO2 conditions rewired its metabolism to supply carbon skeleton for ammonium recycling, during which process the expression of C4 genes were up-regulated as a result of a hitchhiking process. This study provides new insights into the adaptation of the C3 model plant Arabidopsis under low CO2 conditions and suggests that low CO2 can facilitate the evolution of C4 photosynthesis beyond the commonly assumed role of being a selection pressure. [ABSTRACT FROM AUTHOR]

Speciation events often occur with adaptive radiation. The factors that promote these adaptive radiating species diversity patterns have intrigued biologists for more than a century. In the present study, we used the adaptive radiated genus Ligustrum to evaluate the relative contributions of the environment, species interactions, phylogenetic diversity, and diversification rates in generating extant species diversity patterns. Using complete chloroplast genome data, we reconstructed the highly supported and dated backbone phylogenetic relationships of Ligustrum. Biogeographic results indicated that Ligustrum originated in Southwest China during the Oligocene and spread to suitable areas that were warm and humid via 18 dispersal events. For the overlapping ranges of species pairs, a smaller phylogenetic distance was detected in high species overlap than in low species overlap, which is consistent with no significant difference in niche among the different species. We found that the phylogenetic diversity and interspecies competition induced by insignificant niche divergence shaped the global pattern of Ligustrum diversity. [ABSTRACT FROM AUTHOR]

We describe a new species of Ampelopsideae (Vitaceae), Nekemias mucronata sp. nov., from the Rupelian of Cervera (Spain) and revise another fossil species, Ampelopsis hibschii, originally described from Germany. Comparison with extant Ampelopsideae suggests that the North American species Nekemias arborea is most similar to Nekemias mucronata while the East Mediterranean Ampelopsis orientalis is the closest living relative of A. hibschii. Our review of fossil data indicates that, during the Eocene, four species of Ampelopsideae occurred in Eurasia, that is, N. mucronata in the Czech Republic, A. hibschii in Kazakhstan, and two fossil species in the Far East (Ampelopsis cercidifolia and Ampelopsis protoheterophylla). In the Oligocene, a new species, Ampelopsis schischkinii, appeared in Kazakhstan; meanwhile, N. mucronata spread eastwards and southwards, and A. hibschii mainly grew in Central Europe. In the late Oligocene, N. mucronata became a relict in the Iberian Peninsula and Nekemias might have persisted in Western Eurasia until the latest Miocene (“Ampelopsis” abkhasica). The last occurrence of A. hibschii was in the Middle Miocene in Bulgaria, probably a refuge of humid temperate taxa, along with Ampelopsis aff. cordata. Carpological remains suggest that this lineage persisted in Europe at least until the Pleistocene. Our data confirm previous notions of the North Atlantic and Bering land bridges being important dispersal routes for Ampelopsideae. However, such dispersion probably occurred during the Paleogene rather than the Neogene, as previously suggested. A single species of Ampelopsideae, A. orientalis, has survived in Western Eurasia, which appears to have been linked to a biome shift. [ABSTRACT FROM AUTHOR]

The results of a palynological study of the middle Eocene-lowermost Oligocene strata of the Shagap and Landzhar outcrop sections (southern Armenia) are presented. A series of stratigraphically important dinoflagellate cyst events were recognized in the uppermost Lutetian-lowermost Rupelian parts of the sections, including the lowermost occurrences of the key-species Rhombodinium draco, Schematophora speciosa, Hemiplacophora semilunifera, Hapsocysta kysingensis, Thalassiphora? cf. rota, Rhombodinium porosum, Glaphyrocysta semitecta, Reticulatosphaera actinocoronata, Stoveracysta ornata-group and Wetzeliella gochtii. Based on the first-order calibrations with calcareous nannoplankton and foraminifers, R. draco first occurs at the Lutetian-Bartonian transition, while the lowermost occurrence of R. actinocoronata is very close to the Bartonian-Priabonian boundary. The analysis of the ratios of palynogroups and dinoflagellate eco-groups permits to interpret the environmental conditions during the accumulation of regional formations: (1) a major marine transgression started at the beginning of the Lutetian and the gradual deepening of the marine basin occurred during the middle-late Lutetian (Arpa Formation); (2) the marine transgression, accompanied by deepening, continued during the early Bartonian, but towards the end of the Bartonian slightly shallower depositional conditions were established (Azatek Formation); (3) the sea continued to gradually become shallower during the Priabonian (Urtsadzor Formation) and, finally, the maximum of regression was observed at the Eocene-Oligocene transition, ending with the establishment of brackish environments at the beginning of Rupelian (Shagap Formation). [ABSTRACT FROM AUTHOR]

The greenhouse to icehouse transition at the Eocene-Oligocene boundary (34 Ma) marked the appearance of continental-scale glaciation in Antarctica. The material recovered from Ocean Drilling Program Site 696 is the only record spanning this major climatic shift in the Weddell Sea region. Using scanning electron microscopy, quartz microtextures in 13 samples across the Eocene-Oligocene transition were analyzed to understand the degree of glacial modification and the transportation history of the >150 µm material. The quartz grains were visually grouped, characterized, and interpreted by grain outline, relief, and surface microtextures. Glacial textures are present throughout the entire interval (34.4-33.2 Ma), with the proportion of icebergrafted grains in each sample decreasing into the early Oligocene (33.6 Ma), accompanied by an increase in the frequency of eolian and sea-ice-rafted grains. Mass accumulation rates reveal that the flux of iceberg-rafted debris increased coincident with the flux of eolian and sea-ice-rafted grains following 33.6 Ma, suggesting a strong coupling between land-ice development and high-latitude atmospheric processes. When compared with other Antarctic climate proxy data sets, the intensification of ice rafting at Site 696 occurred after ice-sheet inception in East Antarctica. The prominent influx of terrigenous material after 33.6 Ma points to strengthened glacial conditions accompanied by major changes in the environment of the Weddell Sea region, supporting the idea of a high-latitude role in climate perturbations, in agreement with interpretations of other global proxies. [ABSTRACT FROM AUTHOR]

The evolution of faults within the same stress field is frequently influenced by numerous factors, involving the reactivation of pre-existing structures, stress transmission through ductile detachment layers, and the growth, interaction, as well as linkage of new fault segments. This study analyses a complex multi-phase oblique extension fault system in the Nanpu Sag (NPS) of the Bohai Bay Basin (BBB), China. High-resolution three-dimensional (3D) seismic data and analogue modelling indicate that the oblique extensional reactivation of pre-existing structures governs the sequential arrangement of fault segments in the caprock, and they dip synthetically to the reactivated fault at depth. During the NW-SE extension in the Eocene, the predominant movement of the pre-existing fault is strike-slip. Subsequently, during the N-S extension since the Oligocene, inclined at 20° to the pre-existing fault, forming splay fault segments and ultimately creating large en-échelon arcuate faults linked by relay ramps. Using fault throw-distance (T-D) and laser scanning, we reconstructed the fault evolution model of oblique extension reactivation in the presence of a ductile detachment basement. Our study illustrates that the arcuate faults can be categorized into linear master fault segments controlled by pre-existing structures, bending splay faults in the termination zone, and normal fault segments responding to the regional stress field. The interaction between faults occurs among normal faults and strike-slip faults, and the kinematic unification of the two fault systems is accomplished in the intersection zone. As the faults continue to evolve, the new fault segments tend to relinquish the control of pre-existing structures and concentrate more on the development of planar and continuous major faults. The ductile detachment layer significantly contributes to the uniform distribution of strain, resulting in narrow shear zones and discontinuous normal faults in its absence. [ABSTRACT FROM AUTHOR]

The results of studies of the regional structure of Solenovian deposits of the Early Oligocene Rupelian Stage in the Cisсaucasian–Caspian region, which represented the northern slope of Eastern Paratethys in the Cenozoic, are presented. The geological structure and paleogeographic conditions in the basin during the Solenovian (second half of Early Oligocene) were refined based on a comprehensive interpretation of geological and geophysical materials. The spatial consequences of the sea level drop in Eastern Paratethys during the Oligocene regressions are traced. The periodic draining of shelf areas is reflected in the structure of erosional unconformities and buried river incisions. It has been established that the most significant was the late Solenovian regression with a relative sea level drop by more than 500 m. Consequently, a prominent unconformity surface, complicated by river incisions, was formed in the sedimentary sequence in the shelf part of the paleobasin (Maikop seismic sequence). Erosion ledges and landslide bodies formed on the slopes, and basin-infill complexes were accumulated in depressions. [ABSTRACT FROM AUTHOR]

The article focuses on Oligocene and Miocene blowtorch volcanism within the California Borderland and its influence on the plate-boundary transition. It details the methods for sample collection, including ROV deployments and geological analyses, and presents results from 40Ar/39Ar age determinations and whole rock geochemistry. It also includes a regional plate motion model constructed using GPlates software.

In fold-and-thrust belts where there is a high degree of structural complexity, artificial geometrical distortions are often present on seismic reflection profiles. These need to be minimized during modelling. We document a workflow in which depth mapping, velocity model building, well calibration and cross-section balancing are integrated into the seismic interpretation process to generate trustworthy structural models in complex zones. The proposed methodology is exemplified by a case study from the foothills zone of the Colombian Eastern Cordillera. In addition, sequential kinematic restoration of the modelled structure allowed an evaluation to be made of hydrocarbon migration routes during the period between the Oligocene and the middle Miocene. Following the previously mentioned workflow, we document a failed exploratory case study where all elements of the petroleum system are present except the trap. In this context, the documented case is a typical velocity pull-up. From this and published case studies, we conclude that in Andean settings and probably most on land contractional-foothill settings, the use of seismic images only does not provide enough evidence for the presence of traps and additional surface geological signatures must be documented. The proposed workflow therefore appears to be a useful tool for evaluating the exploration risk in structurally complex fold-and-thrust belt settings. [ABSTRACT FROM AUTHOR]

U–Pb, and zircon and apatite fission track data provide a powerful means to characterise the Late Cretaceous to Late Oligocene source-to-sink system and continent evolution in central Zealandia. Our dataset includes samples from potential source rocks in northwest Nelson (Takaka and Buller terranes; Karamea, Tobin, Darran and Separation Point suites) and Cenozoic sediments in the Taranaki and King Country basins. Zircon (ZFT) and apatite (AFT) fission track data for basement rocks indicate 7.5 to 10 km of Late Cretaceous to Paleogene exhumation, requiring a substantial Early Cretaceous to Paleogene mountain range in northwest Nelson, which was eroded to sea level by the Late Oligocene. Some 54% of the detrital zircon content in basin sandstone beds have Separation Point Suite U–Pb age, 24% have Karamea Batholith age and 19% have Darran and Tobin suites age. The remainder could be from the Buller and/or Takaka terranes. Revised Late Eocene and Oligocene paleogeographic maps for the basins define the sediment transport routes until termination during 29 to 26 Ma due to shortening across central to southern parts of the Taranaki Fault System, which dates the timing of subduction initiation along the Hikurangi margin of the modern Australia-Pacific plate boundary. [ABSTRACT FROM AUTHOR]

One of Earth’s most fundamental climate shifts, the greenhouse-icehouse transition 34 million years ago, initiated Antarctic ice sheet buildup, influencing global climate until today. However, the extent of the ice sheet during the Early Oligocene Glacial Maximum (~33.7 to 33.2 million years ago) that immediately followed this transition—a critical knowledge gap for assessing feedbacks between permanently glaciated areas and early Cenozoic global climate reorganization—is uncertain. In this work, we present shallow-marine drilling data constraining earliest Oligocene environmental conditions on West Antarctica’s Pacific margin—a key region for understanding Antarctic ice sheet evolution. These data indicate a cool-temperate environment with mild ocean and air temperatures that prevented West Antarctic Ice Sheet formation. Climate–ice sheet modeling corroborates a highly asymmetric Antarctic ice sheet, thereby revealing its differential regional response to past and future climatic change. [ABSTRACT FROM AUTHOR]

Anomaluroid rodents (i.e. Anomaluridae + Zenkerellidae) have a long evolutionary history in Africa dating back to at least the middle Eocene, but Palaeogene fossil members of the anomaluroid crown group have never been found south of the Sahara. Here, we describe the oldest crown anomaluroid from sub-Saharan Africa, Eliwourus topernawiensis (new genus and species) from the early Oligocene Topernawi Formation of northern Kenya. Bayesian phylogenetic tip-dating analysis of a combined molecular-morphological dataset places ~29.5 Ma Eliwourus as an advanced stem anomalurid, and suggests that crown Anomaluridae originated ~28.2 Ma. The gliding behaviour seen in all crown anomalurids had, therefore, likely evolved before the close of the early Oligocene. Bayesian geocoordinates analysis places the origin of crown Anomaluroidea (~47.2 Ma) in northern Africa, and identifies a stem anomalurid dispersal into equatorial eastern Africa in the latest Eocene or earliest Oligocene. We present the first quantitative analysis of the pace of anomaluroid dental evolution and confirm a remarkably slow or bradytelic rate of phenotypic change, despite significant transformations in postcranial morphology related to the evolution of gliding behaviour during the same interval. The Topernawi area was evidently sufficiently forested during the early Oligocene to support both arboreal rodents and primates. [ABSTRACT FROM AUTHOR]

Despite their relative abundance, members of the family Hypertragulidae (Artiodactyla, Mammalia) have proved a conundrum regarding species diversity in the Turtle Cove Member (Oligocene) of the John Day Formation, located in central and eastern Oregon. Three species and two separate genera are described in the area, but previous research lacks statistical support for this level of variation. We use coefficients of variation (V) on measurements of dentition and astragali of hypertragulid specimens designated Hypertragulus hesperius, Hypertragulus minutus, and Nanotragulus planiceps as a metric for determining whether there were multiple species present in the population. Asymptotic and modified signed-likelihood ratio V equality tests show that V values of anterior-posterior molar length and transverse molar width vary significantly when comparing single species of modern ecological analogs (Muntiacus muntjak, Muntiacus reevesi, and Tragulus javanicus) to groupings of a combined population. However, the V equality tests on dental and postcranial measurements yield almost no significant results when comparing variation in the extinct John Day hypertragulids to an extant population comprised of a single species. Similar comparisons between astragali measurements of hypertragulids and T. javanicus express no significant difference in the level of variation from the combined population to a modern single species. The low level of variation in the hypertragulids and the lack of differentiation between dental characters of individuals does not statistically support the hypothesis that there were multiple species present in the population, suggesting either that cryptic species may be present but impossible to identify without soft tissue remains, or there may have been taxonomic over-splitting of a single hypertragulid species in the John Day region. [ABSTRACT FROM AUTHOR]

The Yinggehai Basin is situated at the junction of Indochina and the northern South China Sea (SCS). The origin of the Yinggehai Basin is generally believed to be controlled by the rotation of the Indochina block along the Red River shear zone (RRSZ), which was formed by the collision of India with Asia during the Oligocene. However, the Eocene structural mechanisms of this basin remain debatable. Some studies suggest that the Eocene reactivation of the palaeo‐suture zone (which serves as a precursor to the RRSZ) has influenced the region. In contrast, others propose that the NNW–SSE extension of the northern SCS caused by the subduction of the palaeo‐SCS towards Borneo in the Eocene has played a significant role. To address these controversies, our study takes into account these two crucial factors using physical analogue modelling. The experimental results, including slow sinistral strike‐slip along the palaeo‐suture zone and the adjacent NNW–SSE extension, successfully explain the observed fault pattern during the Eocene period. It is noteworthy that the former primarily controlled the Eocene structure in the northern region of the Yinggehai Basin, whereas the latter played a pivotal role in shaping the ENE–WSW Eocene structures on the eastern slope of the basin. The westward propagating faults of the Qiongdongnan basin are cut off by the Yinggehai Basin structures at later large‐scale rotation stage. The experiment indicates that the basin evolution exhibits diachronous characteristics, with subsidence in the south occurring later than in the north. Our modelling results provide valuable insights into the key controlling factors that shaped the evolution of the basin during each stage. Furthermore, our findings offer evidence of the interaction between two significant tectonic processes: Indochina extrusion and the opening of the SCS. [ABSTRACT FROM AUTHOR]

Gymnurid rays are found in tropical, subtropical, and temperate regions around the world, where they are associated with sandy or muddy bottoms in coastal areas, being easily distinguished from other rays by the width of the disc. In recent years, the systematics of this family have been revised extensively. However, there has been no comprehensive molecular review of the family based on an adequate sample of species and localities, which may have obscured the presence of distinct evolutionary lineages. The present study was based on samples of 12 of the 13 valid species of the genus Gymnura, which were used for a multilocus reconstruction of the evolutionary history of the family Gymnuridae. Our results indicate the existence of several cryptic gymnurid lineages, within the species Gymnura micrura, Gymnura lessae, Gymnura altavela, and Gymnura poecilura. Also, we indicate that only half of the species that compose the genus are known, as well their conservation status. The analyses also indicate that the gymnurids originated during the Paleocene, with events of dispersal and vicariance occurring through the formation of oceanographic barriers, and species diversification peaking during the Oligocene and Miocene. The results of the present study reinforce the need for a comprehensive revision of the systematics of the family, in particular, the widely distributed species that are considered valid taxa, but may, in fact, represent different cryptic species. The inadequate classification of this cryptic diversity may have negative implications for the development of effective conservation measures. [ABSTRACT FROM AUTHOR]

For sedinentary archives to be used as a record of hinterland evolution, the factors affecting the archive nust be known. In addition to tectonics, a nunber of factors, such as changes in clinate and paleodrainage, as well as the degree of diagenesis, influence basin sedinents. The Indus River delta-fan systen of South-Central Asia records a history of Hinalayan evolution, and both the onshore and offshore sedinentary repositories have been studied extensively to research orogenesis. However, a nunber of unknowns renain regarding this systen. This paper seeks to elucidate the paleodrainage of the Indus River, in particular when it took on its nodern drainage configuration with respect to conjoinnent of the nain Hinalayan (Punjabi) tributary systen with the Indus trunk river. We leverage the fact that the Punjabi tributary systen has a significantly different provenance signature than the nain trunk Indus River, draining nainly the Indian plate. Therefore, after the Punjabi tributary systen joined the Indus River, the proportion of Indian plate naterial in the repositories downstrean of the confluence should have been higher than in the upstrean repository. We conpared bulk Sr-Nd data and detrital zircon U-Pb data fron the Cenozoic upstrean peripheral foreland basin and downstrean Indus delta and Indus Fan repositories. We deternined that throughout Neogene tines, repositories below the confluence had a higher proportion of naterial fron the Indian plate than those above the confluence. Therefore, we conclude that the Indus River took on its current configuration, with the Punjabi tributary systen draining into the Indus trunk river in the Paleogene, early in the history of the orogen. The exact tine when the tributary systen joined the Indus should correlate with a shift to nore Indian plate input in the down-strean repositories only. While the upstrean repository records no change in Indian plate input fron Eocene to Neogene tines, a shift to increased naterial fron the Indian plate occurs at the Eocene-Oligocene boundary in the delta, but sonetine between 50 Ma and 40 Ma in the fan. Though further work is required to understand the discrepancy between the two downstrean repositories, we can conclude that the tributary systen joined the Indus trunk river at or before the start of the Oligocene. [ABSTRACT FROM AUTHOR]

Oriental plane tree (Platanus orientalis) is native to the East Mediterranean region and sister to three western North American species, together forming the Pacific North American–European (PNA‐E) clade. Its sister clade, comprising several eastern North American–Mexican species, has been termed the Atlantic North American (ANA) clade. The origins of P. orientalis and the western North American–western Eurasian disjunction in the PNA‐E clade are poorly understood, with the North Atlantic and Bering land bridges being possible corridors for trans‐continental migration. Molecular phylogenetic studies suggested ancient hybridization between the ANA and PNA‐E clades prior to differentiation of modern species' lineages. We traced ANA‐ and PNA‐E‐specific leaf traits in the fossil record to locate areas of possible ancient hybridization. Leaf traits characteristic of the PNA‐E clade occurred in western North America (late Eocene of Montana, Early Miocene of Alaska) prior to appearing in the European fossil record. Fossil‐species with mixed PNA‐E–ANA leaf traits occurred in the Oligocene of Central Asia and Eocene and Miocene of western North America. In contrast, eastern North America and the Atlantic region hosted fossil‐species with leaf traits characteristic of modern ANA clade members. We propose that precursors of Platanus orientalis migrated to Europe via Beringia and through Central Asia. Initially, these Eurasian ancestors possessed ancestral PNA‐E clade leaf morphologies, which were gradually replaced by P. orientalis‐specific traits. Treated as a single fossil‐species, we document the evolution of P. academiae from predominately three‐lobed leaves in Miocene strata to narrowly five‐lobed leaves resembling modern P. orientalis in younger deposits of Greece. [ABSTRACT FROM AUTHOR]

This paper focuses on the structural and finite strain analysis of the Pelagonian nappe, the HP/LT Ampelakia unit, and the Olympos-Ossa unit in the Olympos-Ossa mountainous area in order to better understand the exhumation history of the Ampelakia unit and the underlain Olympos-Ossa unit. Two main stages of Tertiary deformation were revealed, related to nappe stacking and exhumation processes. During the Paleocene–Eocene crustal subduction, HP/LT metamorphism, compression, and nappe stacking were developed progressively. This D1 stage was terminated with the final SW-ward emplacement of the Ampelakia and Pelagonian nappe on the Olympos-Ossa unit during the Eocene–Early Oligocene. The next stage of deformation, D2, was developed during the Oligocene–Miocene following the orogenic nappes stacking. D2 was considered an extensional event, related to metamorphic isothermal decompression, nappes tectonic denudation, crustal uplift, and final exhumation of the Ampelakia unit and the Olympos-Ossa unit as a tectonic window. The calculated finite strain ellipsoids indicate a main flattening type strain geometry and middle strain intensity, increasing along the nappe contacts. The quartz C-axes diagrams also reveal a flattening type of deformation and non-coaxial flow towards the southwest and northeast at the western and eastern flanks of Olympos-Ossa Mountain, respectively. The calculated Wk vorticity number ranges from 0.23 to 0.93. [ABSTRACT FROM AUTHOR]

The Eocene-Oligocene Transition is one of the major stages of the Cenozoic reshaping of the world oceans with associated changes in climate, of ocean coastlines and circulation patterns. This altogether created challenging environments for fossilization and preservation of native biota. Consequently, well preserved Oligocene fossils are infrequent worldwide and just as rare in the Central Paratethys. The well-preserved Rupelian (Early Oligocene) diatomites from the Skole Nappe, the external unit of the Outer Carpathians in southeastern Poland were deposited in the Central Paratethys. In some samples, in addition to diatoms, sediments also contain a great diversity of other silicified micro- and nannofossils. Here we report our findings of silicoflagellates (fifteen taxa from five genera), two rotosphaeridians, and several morphotypes of fossil scales, some of uncertain taxonomic affinity. Among silicoflagellates, the most common are species from genera Corbisema (C. triacantha, C. hastata, and C. apiculata) and Dictyocha (D. clinata and D. fibula). We also recovered scales of rotosphaeridians (Pinaciophora and possibly Rabdiophrys) and remains of organisms of uncertain affinity (Clathropyxidella and Macrora) often reported together with silicoflagellates. All of these taxa are the first reports for the Central Paratethys. Silicoflagellate species composition is consistent with the datums derived from other fossils. Silicoflagellates, marine diatoms and archaeomonads suggest a neritic depositional environment. [ABSTRACT FROM AUTHOR]

The Oligocene (33.9–23.03 Ma) had warm climates with flattened meridional temperature gradients, while Antarctica retained a significant cryosphere. These may pose imperfect analogues to distant future climate states with unipolar icehouse conditions. Although local and regional climate and environmental reconstructions of Oligocene conditions are available, the community lacks synthesis of regional reconstructions. To provide a comprehensive overview of marine and terrestrial climate and environmental conditions in the Oligocene, and a reconstruction of trends through time, we review marine and terrestrial proxy records and compare these to numerical climate model simulations of the Oligocene. Results, based on the present relatively sparse data, suggest temperatures around the Equator that are similar to modern temperatures. Sea surface temperatures (SSTs) show patterns similar to land temperatures, with warm conditions at mid- and high latitudes (∼60 –90°), especially in the Southern Hemisphere (SH). Vegetation-based precipitation reconstructions of the Oligocene suggest regionally drier conditions compared to modern times around the Equator. When compared to proxy data, climate model simulations overestimate Oligocene precipitation in most areas, particularly the tropics. Temperatures around the mid- to high latitudes are generally underestimated in models compared to proxy data and tend to overestimate the warming in the tropics. In line with previous proxy-to-model comparisons, we find that models underestimate polar amplification and overestimate the Equator-to-pole temperature gradient suggested from the available proxy data. This further stresses the urgency of solving this widely recorded problem for past warm climates, such as the Oligocene. [ABSTRACT FROM AUTHOR]