Late Early Oligocene Research Articles

New data on early Oligocene dormice (Rodentia, Gliridae) from southern Europe: phylogeny and diversification of the family

Rodents of the extant family Gliridae, commonly called dormice, are common in European faunas since the early Eocene. Here we study for the first time specimens from St-Martin-de-Castillon C (France, early Oligocene) previously reported as Gliravus aff. majori and Pseudodryomys aff. fugax. We now refer them to Butseloglis tenuis and Microdyromys misonnei. Besides the French material, new specimens from Montalbán 1D (Spain, early Oligocene) are studied. They include: Butseloglis montisalbani and M. misonnei already known in the locality, but also Oligodyromys libanicus and Glirudinus aff. glirulus reported here for the first time. Previous phylogenies of the family only focused on extant taxa. Here we propose the first phylogenetic analysis of Gliridae including both extant and fossil taxa. The relationships between the taxa show several paraphylies at the generic level and suggest that the classification of the family needs a revision. Two main clades are revealed in our analysis, including most extant taxa, both of them being closely related to the Oligocene genus Microdyromys. By comparing the phylogeny to the evolution of species-richness through time, we show that glirids underwent three major diversification phases. The first diversification event involves several clades of late Eocene and early Oligocene glirids. The second diversification event involves the two main clades still represented today. They both started diversifying in the late Oligocene and led the species richness of the family to reach a peak at the end of the early Miocene. Finally, the third diversification starts in the middle Pliocene and involves mostly extant genera. These diversification phases might have been triggered by successive glaciation events that occurred in the Oligocene, Miocene and Pliocene. A potential evolutionary advantage of this family successfully facing cold climatic events could be the ability to hibernate, acquired as early as the early Oligocene.

Diverse epiphyllous fungi on Cunninghamia leaves from the Oligocene of South China and their paleoecological and paleoclimatic implications

AbstractThe unique co‐occurrence of thyriothecia belonging to three fossil genera of epiphyllous fungi, Stomiopeltites Alvin & Muir (Micropeltidaceae), Callimothallus Dilcher, and Trichothyrites Rosendahl (Microthyriaceae), are reported on the leaves of the same host plant, Cunninghamia shangcunica Kodrul, Gordenko & Sokolova from the Oligocene Shangcun Formation of the Maoming Basin, South China. In China, Stomiopeltites is identified for the first time, Callimothallus is known from the Oligocene and Miocene of Guangxi and Zhejiang provinces, and Trichothyrites previously has been found only in the Eocene palynological assemblages of the Maoming Basin. The presence of abundant and diverse epiphyllous micromycetes, together with the taxonomic composition of the Shangcun megaflora and pollen assemblage, as well as quantitative climatic estimates obtained using Climate Leaf Analysis Multivariate Program, confirm the existence of a warm and humid climate in this region during the late early Oligocene. The geographic and stratigraphic distributions, comparisons with extant analogues, as well as ecological and paleoclimatic implications of the fossil fungi are discussed.

Evolution of petroleum generation and expulsion of the oil-source rock in the north-western Say’un-Masilah Basin as inferred from 1D basin models of a single well (Al-Qarn-01)

The Madbi Shale Formation is the main oil-source rock for conventional petroleum extraction in the east-central Say’un-Masilah Basin. This study explores the generation and expulsion potential of oil from the Madbi source rock system in a deep well location (Al-Qarn-01) in the north-western Say’un-Masilah Basin using geological and geochemical modelling. One-dimensional (1D) basin models were constructed to the estimate thermal regime in the basin and the evolution of oil cracking and expulsion from the organic-rich intervals in the Madbi Formation over the geological time. In the studied Al-Qarn-01 well, the organic-rich intervals in the Madbi Formation are thermally mature, ranging from peak- to late-mature oil window stages; thus, half or more of the kerogen was converted to oil at these maturity stages. The basin modelling results of the studied well (Al-Qarn-01) show that oil was generated and expelled from Madbi source rock intervals in two main phases according to the conversion ratio (TR %) of kerogen. The main conversion of kerogen to oil (TR = 10–50%) occurred between Late Cretaceous and Early Oligocene (80–33 Ma) periods, corresponding to the peak-oil window (0.70–1.00 Easy %Ro). Furthermore, significant amounts of oil were expelled from the source rock, which subsequently migrated into the overlying reservoir rocks in the Early Oligocene time during the initial Tertiary rifting. The late-mature oil window (1.00–1.10 Easy %Ro) commenced during this time, with TRs of 50–77%.

LA "GONFOLITE LOMBARDA": STRATIGRAFIA E SIGNIFICATO NELL'EVOLUZIONE DEL MARGINE SUDALPINO

The Oligocene-Miocene succession of the "Gonfolite Lombarda" outcrops in Western Lombardy and is largely represented in the subsurface of the northern PO Plain. In the this group was considered as a typical example of post- orogenic molasse deposit. The new data suggest that it represents a clastic wedge infilling a deep foreland basin flanking a zone of continental collision. The stratigraphic evolution of the succession strictly reflects the tectono-sedimentary evolution of the basin.
 The succession (almost 3000 m thick) between Como and Varese covers a time span from late early Oligocene (late Rupelian) at least to early Miocene (Burdigalian). It consists of clastic sediments deposited in a deep-sea environment. Both the benthic Foraminifera and the macrofossil assemblages indicate that these sediments were deposited in the epibathial zone (from 500-700 m to 1000-1300 m) throughout all the time span considered. The succession can be splitted in two main segments based on their different sedimentary characters and because they are separated by a regional unconformity corresponding to a hiatus of several million years. The lower one is represented by the Chiasso Formation (about 170m thick) and the upper one by the Gonfolite Group s. Str. (about 2800 m thick).
 The Chiasso Formation is a depositional sequence late Oligocene (late Rupelian to early Chattian) in age. It consists of mudstones and rare thin-bedded turbidites, representing slope or slope-base deposits. The overlying Gonfolite Group represents the build-up of several deep sea fan systems one on top of the other during the very late Oligocene (late Chattian) to the early Miocene (Aquitanian- Burdigalian) and perhaps to the middle Miocene. Resedimented conglomerates infilled deeply incised canyons confined by natural levees in their distal part. The canyons evolved laterally and distally to still partly confined sandy depositional lobes during the early Miocene.
 In the Gonfolite Group three depositional sequences could be recognized. The first one is represented by the Como Conglomerate (800-1500 m thick) and of some heteropic formations, covering a time span from late Chattian to early Burdigalian. This depositional sequence represents an asymmetric megacycle with an initillly very rapid progradation of the conglomeratic system followed by its gradual regression and, in the Como area, by a westward shift of the system axis. Moreover, it is worth mentioning that pebbles of granodiorite-diorite called "ghiandone and serizzo" of the Val Masin0-Val Bregaglia Massif make their appearance already in the basal part of the Como Conglomerate.
 The second depositional sequence consists of the Lucino Conglomerate (800-1000 m thick) and of some heteropic formations. It represents a gradual progradation of the whole deep sea fan system during the late earIy Miocene (Burdigalian).
 In the Varese area, the Gurone Sandstone (120 m thick) may represent a third depositional sequence, which because of its stratigraphic position is younger than the late Burdigalian, and it appears to be deposited prior to the late Miocene (Tortonian).
 The "Gonfolite Lombarda" basin was interested by an intense and continue tectonic activity with at least two periods of "crisis" occurring in the late Chattian and in the early Burdigalian. Because of the strong tectonic Control it's difficult to correlate the "Gonfolite Lombarda" depositional sequences with the generalized sea level curves.

The regional facies analysis and depositional environments of the Oligocene and Lower Miocene deposits; Zagros Basin, SW of Iran

A regional transect is selected to study the paleoenvironment of the Oligocene and Lower Miocene deposits in the Zagros Basin (Persian Gulf Foreland Basin to the High Zagros). This study rebuilds the sedimentary environments and paleogeography of the Zagros basin deposits in the Oligocene and the Lower Miocene. A transect consists of two stratigraphic subsurface sections at the Persian Gulf Foreland Basin, five stratigraphic subsurface sections at the Dezful Embayment, two stratigraphic outcrop sections at the Zagros Simply Folded and one exposure section at the High Zagros. The sediments are included Asmari Formation and the Pabdeh Formation. Lithostratigraphy studies show that the Pabdeh Formation has been composed of an alternation of marls and medium-bedded argillaceous limestone. The Asmari Formation is generally composed of medium- to thick-bedded limestone. Micropaleontology studies offer Early Oligocene for Pabdeh Formation and Early–Late Oligocene to Early Miocene age for Asmari Formation. Variety in fabrics, textures and fauna features has produced 13 microfacies and based on geometry, lateral and vertical facies relationships, the homoclinal ramp is proposed for the Oligocene and Lower Miocene deposits. Hence, corresponding to this research, the Rupelian sedimentation has occurred in the Dezful Embayment and Zagros Simply Folded, so that a systematic progradation suggests from Zagros Simply Folded (N/NE) (Asmari/Pabdeh Formation) to the Dezful Embayment (S/SW) (Asmari carbonate system). Following a regression system during the Late Oligocene to the Early Miocene, continuing sedimentation uniformly has been felt out in the shallow water system throughout the study area.

Skeleton of a new owl from the early Eocene of North America (Aves, Strigiformes) with an accipitrid-like foot morphology

ABSTRACT We describe a partial skeleton of a large-sized owl from Wasatchian strata of the Willwood Formation (Wyoming, U.S.A.). The holotype of Primoptynx poliotauros, gen. et sp. nov., includes all major postcranial bones and is one of the most substantial Paleogene records of the Strigiformes. The fossil shows that owls exhibited a considerable morphological diversity in the early Eocene of North America and occupied disparate ecological niches. As in the protostrigid taxon Minerva from the late early to early middle Eocene of North America, but unlike in extant owls, the ungual phalanges of the hallux and the second toe of the new species are distinctly larger than those of the other toes. Primoptynx poliotauros gen. et sp. nov., however, does not exhibit the derived tibiotarsus morphology of the Protostrigidae. Even though the new species may well be a stem group representative of protostrigid owls, current data do not allow an unambiguous phylogenetic placement. Concerning the size of the ungual phalanges, the feet of P. poliotauros correspond to those of extant hawks and allies (Accipitridae). We therefore hypothesize that it used its feet to dispatch prey items in a hawk-like manner, whereas extant owls kill prey with their beak. Primoptynx and protostrigid owls were possibly specialized in foraging on prey items that required an accipitrid-like killing strategy, such as larger-sized or more defensive mammals. The extinction of these peculiar owls may have been related to the radiation of accipitrid diurnal birds of prey, which appear to have diversified in the late Eocene and early Oligocene.

Phylogenetic relationships of the Chinese torrent frogs (Ranidae: Amolops) revealed by phylogenomic analyses of AFLP-Capture data

The torrent frog genus Amolops contains nearly sixty species distributed in swift mountain streams throughout southeast Asia. The taxonomy of this genus has proven complicated due to unstable morphological diagnostic characters. The relationships of Amolops species and species groups were not readily resolved with a small number of molecular markers. Here, we applied the novel AFLP-Capture approach and acquired two large datasets (242 anonymous nuclear sequences and the mitochondrial genome) from 70 Chinese Amolops samples to study their relationships. The phylogenies inferred from the nuclear data and the mitochondrial data were both robust and revealed a primary phylogenetic split between eastern and western Chinese Amolops species. The relationships of the six species groups were clarified. While the three species groups in east China (the A. ricketti, A. daiyunensis and A. hainanensis groups) were monophyletic, the three species groups in the west (the A. mantzorum, A. monticola and A. marmoratus groups) were not monophyletic, suggesting a need for further investigation and revision. The robust phylogenies also provided new insights into species relationships, especially for the A. mantzorum group, which has been difficult to resolve due to multiple speciation events occurring approximately 7–8 million years ago. The divergence times estimated with the nuclear data indicated that the ancestor of the Chinese Amolops appeared in the late Eocene or early Oligocene, and that speciation events in the Chinese Amolops were often related to geological events (e.g. the uprising of mountains and the formation of islands). By including the mitochondrial sequences from GenBank, a more comprehensive Amolops phylogeny was constructed that reflected the origin of the Chinese Amolops. Based on all these results, a dispersal scenario of the torrent frogs was hypothesized. Our research serves as the first example of using AFLP-Capture to obtain a large amount of data for shallow-scale phylogenetic and taxonomic studies, which should be useful for other nonmodel organism groups.

ГЕОЛОГО-ГЕОГРАФІЧНІ ОСОБЛИВОСТІ ФОРМУВАННЯ, ПОШУКУ ТА ПРОГНОЗУ УКРАЇНСЬКОГО БУРШТИНУ-СУКЦИНІТУ

The purpose of this study is to determine the geological and geographical features of the transformation of resin secretions of conifers during the transition from living matter to inanimate (mineral) in the process of several stages of fossilization; formation of succinite-amber placers, as well as substantiation of prognosis assessment of prospects for discovery of new deposits and amber manifestations in the context of their ecologically safe and ecologically expedient extraction. The natural-geographical paleocomplexes of the south-eastern part of the Baltic-Dnieper amber-bearing province in the Eocene-Oligocene are characterized, which caused the accumulation of primary biogenic-sedimentary deposits of resin secretions (proto-amber) and conditions of formation of weeds of different ages. These placers are divided by genesis into indigenous, coastal, marine and estuarine delta and delta of the first intermediate reservoirs, formed in the post-Buchach period - late Middle - Late Eocene and early Oligocene and continental polygenetic placers due to in the late Oligocene, Neogene and Anthropogenic. It has been established that the root source of succinite amber in Ukraine was biogenic sedimentary deposits of resin secretions of vegetation characteristic of the central part of modern Ukraine, while in foreign literature it is believed that the main source of Ukrainian amber is its transfer from Scandinavia by coastal banks or river streams and glaciers from the Baltics. The substantiation of the prognosis of new industrial deposits of amber-succinite discovery in Ukraine is stated. Attention is paid to the problem of development of valuable gem deposits - illegal amber mining, the negative consequences of which are considered as manifestations of natural geological processes.

Pseudocricetodontinae (Mammalia, Rodentia) from the Paleogene of south-east Serbia

Pseudocricetodontines from the late Eocene and early Oligocene of south-east Serbia are described. The Pseudocricetodontinae is a clade with a Eurasian geographical range during most of the Oligocene. The subfamily and genera included are briefly discussed. Originally, it contained Pseudocricetodon and Heterocricetodon only, but the number of genera included has grown to at least seven genera during the last decades. Differences in opinion about the content of the subfamily are for a part due to lack of studies in which the Paleogene cricetids from Asia and Europe are directly compared. The material from south-east Serbia described below is assigned to three species: Pseudocricetodon cf. montalbanensis Thaler, 1969, P. heissigi nov. sp. and Heterocricetodon serbicus nov. sp.

World travellers: phylogeny and biogeography of the butterfly genus Leptotes (Lepidoptera: Lycaenidae)

AbstractLeptotina butterflies (Lycaenidae, Polyommatiinae) are found mostly in tropical and subtropical areas around the globe, marginally penetrating into temperate regions. Here, we investigated phylogenetic and biogeographical relationships of most representatives of the subtribe, using both likelihood and Bayesian approaches. We also estimated the timing of their diversification. And lastly, we studied phylogeographic patterns of the most widespread species, Leptotes pirithous. DNA sequences from two mitochondrial (COI, COII) and two nuclear genes (wingless, Ef1α) were analysed for 13 species of the genus Leptotes Scudder and one species of the genus Cyclyrius Butler. Both genera together form a monophyletic clade, and Cyclyrius is rooted deep inside Leptotes. Therefore, we designate Cyclyrius to be a junior synonym of Leptotes. According to our study, the genus Leptotes originated between the late Eocene and early Oligocene (35–31 Ma). During the Miocene it dispersed to the rest of the southern hemisphere, with further speciation events within the Indo‐Australian region, and separate radiations in the Americas and the Afrotropics. Leptotes webbianus from the Canary Islands turned out to be sister to the American clade from which it split c. 12 Ma. Leptotes pirithous originated in Madagascar c. 4 Ma and invaded the whole of Africa and southern Europe, including numerous surrounding islands. Populations of L. pirithous from Mauritius and Madagascar turned out to represent a distinct species (Leptotes durrelli sp.n.) and the same applies to the Australasian populations of Leptotes plinius (Leptotes lybas stat. rev.).This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:20308930‐988B‐4327‐A35F‐CC983D46263B.

A multilocus phylogenetic framework of the tribe Aeromachini (Lepidoptera: Hesperiidae: Hesperiinae), with implications for taxonomy and biogeography

AbstractThe Oriental tribe Aeromachini (Lepidoptera: Hesperiidae: Hesperiinae) is diverse and widespread, but its monophyly and circumscription remain unresolved. In this study, we inferred phylogenetic relationships within the tribe using two mitochondrial (16S and COI‐COII) and two nuclear genes (EF‐1α and Wingless) from 71 samples representing all of the known genera of Aeromachini (s.l.). Phylogenetic topologies obtained from two model‐based methods (maximum‐likelihood and Bayesian inference) were largely congruent, showing that Aeromachini was monophyletic. Many genera within Aeromachini were polyphyletic, especially Arnetta, Thoressa, Ampittia and Sovia. Based on these results, we propose a new classification consisting of 14 genera, of which two are newly described: Halpemorpha gen.n. and Praethoressa gen.n. Ampittia and Ochus are restructured, with: (i) Ampittia nana and Ampittia dalailama moved to Aeromachus, (ii) new combinations proposed for the remaining Ampittia species, and (iii) a new combination, Ampittia subvittatus comb.n., proposed. The Oriental members of the genus Arnetta belong to this tribe, but the African Arnetta hyposticta was found to be embedded into the outgroup and closely related to Isoteinon. We propose that hyposticta be reinstated in the genus Galerga Mabille, along with two other African species (fito and ellipsis). Thoressa is polyphyletic, with three distinct lineages. The type species Thoressa masoni forms a clade closely related to the sister genera Sebastonyma and Parasovia. We thus describe Praethoressa gen.n. to include the species varia (formerly of Thoressa), and transfer the remaining Thoressa to Pedesta, which is confirmed as a valid genus. Although the relationships of some genera remained unsolved in our work, the present phylogenetic hypothesis will serve as a reference for further studies. A secondary calibration was used to estimate the divergence time, which indicated that the diversification of Aeromachini started in the late Eocene and early Oligocene (c. 34.22 Ma). Further, ancestral range estimates indicated that the common ancestor of Aeromachini originated in Southeast Asia. Diversification in situ and range expansion to adjacent areas have played essential roles in the evolution of Aeromachini, but founder‐event speciation and vicariance also have likely been important factors in shaping the biogeographical history of this tribe.This published work has been registered on ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:AA11191A-A4E2-47C5-B47B-445E6A2A9E5D.

Structural and Sedimentary Characteristics of Hydrocarbon-Rich Sags in Lacustrine Sub-Basin of Half Graben Type, Pearl River Mouth Basin, South China Sea

Pearl River Mouth Basin undergoes complex tectonic evolution processes and forms lacustrine, transitional and marine sediments. Drilling shows that there exist large petroleum reserves in the hydrocarbon-rich sags of Pearl River Mouth Basin, South China Sea. To reduce the risk, the exploration, structural and sedimentary characteristics of the hydrocarbon-rich sags should be identified and described. Drilling, seismic, and microfossil data are integrated to interpret the structural and sedimentary evolution of the hydrocarbon-rich sags in Pearl River Mouth Basin. By analyzing the tectonic and sedimentary evolutionary characteristics, three conclusions may be drawn: 1) The present regional tectonic characteristics of the PRMB are formed by mutual interactions of the Eurasian Plate, Pacific Plate, Philippine Plate and Indian Plate. During the Paleocene to early Eocene and late Eocene and early Oligocene, the PRMB is at the rifting stage. During the late Oligocene, the PRMB was at the rifting-depression transitional stage. After the Oligocene, the PRMB is at the depression stage. 2) Tectonic conditions control the sedimentation process in the hydrocarbon-rich sags. During the lacustrine sedimentation stage, synsedimentary faults and intense faulting control the sedimentation. During the transitional sedimentation stage, weak fault activity influences the deposition process in the hydrocarbon-rich sags. During the marine sedimentation stage, weak fault activity and depression activity control the deposition process in the hydrocarbon-rich sags. 3) Tectonic evolution affects the deposition process. The lacustrine, transitional and marine sedimentation corresponds to different tectonic conditions. The lacustrine sedimentation is formed under fault activity during the rifting stage. The transitional sedimentation is formed under weak fault activity during the late rifting stage. The marine sedimentation is formed under weak fault activity and depression activity during the rifting-depression and depression stages. 4) The half graben is beneficial for the formation of lacustrine source rocks, which is responsible for the hydrocarbon-rich sag. Therefore the half graben mode contributes to the hydrocarbon-rich sags.

A dated molecular perspective of eucalypt taxonomy, evolution and diversification

The eucalypts, which include Eucalyptus, Angophora and Corymbia, are native to Australia and Malesia and include over 800 named species in a mixture of diverse and depauperate lineages. We assessed the fit of the eucalypt taxonomic classification to a phylogeny of 711 species scored for DNA sequences of plastid matK and psbA–trnH, as well as nuclear internal transcribed spacer and external transcribed spacer. Two broadly similar topologies emerge from both maximum likelihood and Bayesian analyses, showing Angophora nested within Corymbia, or Angophora sister to Corymbia. The position of certain species-poor groups on long branches fluctuated relative to the three major Eucalyptus subgenera, and positions of several closely related species within those subgenera were unstable and lacked statistical support. Most sections and series of Eucalyptus were not recovered as monophyletic. We calibrated these phylogenies against time, using penalised likelihood and constraints obtained from fossil ages. On the basis of these trees, most major eucalypt subgenera arose in the Late Eocene and Early Oligocene. All Eucalyptus clades with taxa occurring in south-eastern Australia have crown ages <20 million years. Several eucalypt clades display a strong present-day geographic disjunction, although these clades did not have strong phylogenetic statistical support. In particular, the estimated age of the separation between the eudesmids (Eucalyptus subgenus Eudesmia) and monocalypts (Eucalyptus subgenus Eucalyptus) was consistent with extensive inland water bodies in the Eocene. Bayesian analysis of macroevolutionary mixture rates of net species diversification accelerated in five sections of Eucalyptus subgenus Symphyomyrtus, all beginning 2–3 million years ago and associated with semi-arid habitats dominated by mallee and mallet growth forms, and with open woodlands and forests in eastern Australia. This is the first time that a calibrated molecular study has shown support for the rapid diversification of eucalypts in the recent past, most likely driven by changing climate and diverse soil geochemical conditions.

Chlorocyon phantasma, a Late Eocene Borhyaenoid (Mammalia: Metatheria: Sparassodonta) from the Los Helados Locality, Andean Main Range, Central Chile

Sparassodont metatherians were the dominant terrestrial mammalian predators during South America's long Cenozoic isolation. This group's early fossil record is very poor, however, particularly for the late Eocene and early Oligocene. Here, we describe a new sparassodont, Chlorocyon phantasma, gen. et sp. nov., based on a specimen from Los Helados, a new locality within the Abanico Formation of the Andean Main Range of central Chile. New 40Ar/39Ar dates at Los Helados bracketing the fossil-bearing level constrain the age of this specimen to 37–36 Ma (late Eocene), indicating that this new taxon likely pertains to the Mustersan South American Land Mammal “Age.” Chlorocyon is the first Paleogene sparassodont reported from Chile and the first sparassodont described from the Abanico Formation. Distinctive features, including a p3 with an anterior edge that is more curved than the posterior edge and the lack of a hypoconulid on m4, suggest that Chlorocyon is a borhyaenoid closely related to Pharsophorus or Plesiofelis, although much smaller. Chlorocyon represents a welcome addition to the sparse record of late Eocene sparassodonts and indicates that the diversity of non-proborhyaenid borhyaenoids prior to the late Oligocene was greater than previously thought.

Terrestrial cooling record through the Eocene-Oligocene transition of Australia

Abstract A new mid-latitude terrestrial climate proxy record is presented for southeastern Australia. The Middle Eocene to Middle Miocene palynofloral and δ13C record of the Latrobe Group, Gippsland Basin, details that the climate of southeastern Australia, paleolatitude 60–50°S, supported the growth of highly diverse subtropical to cool-temperate rainforests. These forests are characterized by mesothermal to microthermal floral elements that are here interpreted as subtropical (Malvacipollis subtilis and Cupanieidites orthoteichus dominated palynofloras), warm-temperate (Beaupreadites elegansiformis and Phyllocladus mawsonii dominated palynofloras) and cool-temperate (Nothofagus spp. and Dacrycarpidites australiensis dominated palynofloras) rainforests. The palynofloral record of the Latrobe Group indicates that mean annual temperatures were between 20 and 24 °C during the Middle Eocene resulting in subtropical rainforests, between 14 and 20 °C for the late Middle Eocene to earliest (i.e. pre-Oi1) Oligocene resulting in warm-temperate rainforests, between 10 and 14 °C for the late Early Oligocene to Early Miocene resulting in cool-temperate rainforests and between 14 and 20 °C in the Middle Miocene, facilitating the resurgence of warm-temperate rainforest floras. Rainfall was also likely in excess of 1500 mm throughout the Middle Eocene to the Middle Miocene in southeastern Australia. The climatic trends preserved within this mid-latitude terrestrial record relate to global Cenozoic cooling, the exception being the Middle Miocene records, which instead relate to the Middle Miocene Climatic Optimum. In the mid-latitude Gippsland Basin, cooling appears to have begun in the Middle Eocene. Correlation of our palynoflora with records from Antarctica and New Zealand, in addition to benthic δ18O records, reaffirms that the Latrobe Group coals provide a long-term, largely authochthonous mid-latitude floral record that directly relates to global climatic evolution through the Cenozoic. Our new mid-latitude terrestrial record provides critical insight into the validation of Eocene-Oligocene climate models and improves our understanding of mid-latitude terrestrial ecosystem responses to increased carbon dioxide forcing. The correlation between the δ13C values of the Yallourn and Morwell coal seams to benthic δ13C records also highlights that a relationship exists between the terrestrial and marine benthic δ13C record.

Postcollisional delamination and partial melting of enriched lithospheric mantle: Evidence from Oligocene (ca. 30 Ma) potassium-rich lavas in the Gemuchaka area of the central Qiangtang Block, Tibet

Postcollisional potassium (K)-rich magmatic rocks have important implications for unveiling the deep geodynamic processes active during the evolution of orogenic belts and the surface uplift of plateaus. However, their petrogenesis remains highly controversial. Here we report on zircon U-Pb and mineral Ar-40-Ar-39 age, zircon Hf-O isotope, mineral composition, whole-rock major and trace element composition, and Nd-Sr isotope data for the postcollisional K-rich lavas in the Gemuchaka area of the central Qiangtang Block (central Tibet). Age dating suggests that these lavas were generated in the late Early Oligocene (ca. 30 Ma). Two series of rocks were recognized: silica-undersaturated and -saturated lavas. Both series are geochemically characterized by continuous variation trends. All rocks are enriched in light rare earth elements (LREEs) relative to heavy REEs (HREEs) and depleted in Ta-Nb-Ti, with negligible Sr and Eu and obviously positive Pb anomalies. The rocks have higher Th/ La (0.2-0.8) and Nb/Ta (18.6-19.8) values than asthenospheric mantle-derived rocks but slightly variable values of epsilon(Nd) (t) (-6.0 to -4.6), (Sr-87/Sr-86)(i) (0.7076-0.7083), and zircon epsilon(HF)(t) (-7.2 to +0.8) and delta O-18 (7.1-8.5 parts per thousand). We suggest that the parental magmas of these K-rich lavas were likely derived by variable partial melting of lithospheric mantle metaso-matized by subducting continental sediment-derived melts with the addition of minor asthenospheric components. Element modeling results suggest that the basic end members were likely generated by fractionation processes dominated by olivine and minor clinopyroxene from parental magmas, and some other evolved rocks were generated by crystal (olivine, clinopyroxene, Fe-Ti oxides) fractionation from basic magmas. Combining geological and Cenozoic magmatic rock data in the Qiangtang Block, we propose that the Gemuchaka magmatism was most likely triggered by the delamination of lithospheric mantle thickened by early (Paleocene- Eocene) intracontinental subduction and subsequent asthenospheric upwelling.

Pappocricetodontinae (Rodentia, Muridae) from the Paleogene of south-east Serbia

Two species of Witenia and a new pappocricetodontine genus and species from the late Eocene and early Oligocene of south-east Serbia are described. The Pappocricetodontinae a subfamily originally based on the small Pappocricetodon rencunensis from China has become a polyphyletic entity due to inclusion of the genus Witenia. The dental morphology of the late Eocene Witenia europea nov. sp. is very similar to that of the middle Eocene Pappocricetodon antiquus, but its molar enamel is more primitive. The small Bustrania dissimile nov. gen. nov. sp., the dominant species in the late Eocene locality of Buštranje, is defined and allocated to the Pappocricetodontinae.

Eocene to Oligocene dinoflagellate cysts from the Tattofte section, western External Rif, northwestern Morocco: Biostratigraphy, paleoenvironments and paleoclimate

The palynological analysis of the Eocene–Oligocene succession from the Tattofte section in the western External Rif (northwestern Morocco) reveals the presence of well-preserved and diverse assemblage, rich in dinoflagellate cysts (dinocysts). Qualitative analyses, especially of the dinocysts, differentiate the individual stages of the deposits, while quantitative analyses permit paleoenvironmental and paleoclimatic interpretations. We assign the lower part of the Tattofte section to the Middle Eocene (Lutetian and Bartonian) and its upper part to the Upper Oligocene (Chattian), and define a hiatus spanning the Late Eocene (Priabonian) and Early Oligocene (Rupelian). The dinocyst marker events used for the biostratigraphic interpretations include the first and last occurrences of marker species, such as Batiacasphaera compta, Castellodinium compactum, Cerebrocysta bartonensis, Distatodinium biffii, Distatodinium paradoxum, Distatodinium ellipticum, Enneadocysta arcuata, Homotryblium floripes, Hystrichokolpoma bullatum, Impagidinium velorum, Lentinia serrata, Pentadinium imaginatum, Rhombodinium spinula, Saturnodinium perforatum and Ynezidinium brevisulcatum, as well as the Chiropteridium spp. acmes. And we equate the Chattian with the dinocyst Distatodinium biffii Zone of Brinkhuis et al. (1992).Changes in the relative abundances of selected dinocyst groups, spores and pollen lead to the distinction, from oldest to youngest, of four marine environments: 1) marginal marine to coastal inner neritic under relatively warm-water during the Middle Eocene; 2) outer neritic to oceanic during a transgressive regime in the early Chattian; 3) fluctuating restricted to open marine in the middle Chattian; and 4) shallow coastal to open marine due to sea-level fall at the top of the section in the latest Chattian, suggested by the Chiropteridium spp. acmes.The acmes of selected thermophilic dinocyst taxa, such as Polysphaeridium spp. and Homotryblium spp. suggest warm water marine conditions, which may be related to the Middle Eocene climatic optimum (MECO) and Late Oligocene warming.

PETROLEUM SYSTEMS IN THE AUSTRIAN SECTOR OF THE NORTH ALPINE FORELAND BASIN: AN OVERVIEW

Two separate petroleum systems have been identified in the Austrian sector of the North Alpine Foreland Basin: a lower Oligocene – Cenomanian/Eocene oil and thermogenic gas system; and an Oligocene‐Miocene microbial gas system. Recent studies by both academic and industry‐based research groups have resulted in an improved understanding of these petroleum systems, which are reviewed in this paper.Lower Oligocene organic‐rich intervals (up to 12 %TOC; HI: 400–600 mgHC/gTOC), capable of generating slightly more than 1 t of hydrocarbons/m2, are the source rocks for the thermogenic petroleum system in the Austrian sector of the North Alpine Foreland Basin. The present‐day distribution of this source rock is controlled by submarine mass movements which removed a large part of the organic‐rich interval from its depositional location during the late early Oligocene. The transported material was redeposited in locations to the south which are at the present day buried beneath Alpine thrust sheets. In addition, source rock units were incorporated into Molasse imbricates during Alpine deformation. Hydrocarbon generation began during the Miocene, and the oil kitchen was located to the south of the Alpine thrust front. Hence, lateral migration over distances of up to 50 km was required to charge the mainly Eocene and Cenomanian non‐ and shallow‐marine sandstone reservoir units. Hydrocarbons are in general trapped in structures related to east‐west trending normal faults, and differences in source rock facies resulted in the development of separate western and eastern oil families. Surprisingly, with the exception of some fields in the eastern part of the study area, associated gas contains varying (and sometimes very high) percentages of primary and secondary microbial methane. The composition of oil in some fields is influenced by both biodegradation and water washing. Post‐Miocene uplift in the Austrian sector of the basin had further effects on biodegradation and the consequent formation of secondary microbial gas, and also resulted in re‐migration.The upper Oligocene to lower Miocene succession (Puchkirchen Group, Hall Formation) provides both source and reservoir rocks for the microbial petroleum system in the Austrian sector of the North Alpine Foreland Basin. TOC contents (<1.0 %) and HI values (<140 mgHC/gTOC) of pelitic source rocks are typically low. Microbial gas was generated shortly after deposition during early diagenesis and was subsequently fixed in gas hydrates. Basin subsidence and high sedimentation rates resulted in decomposition of the hydrates below their stability zone, and reservoirs were filled during the early Miocene. Subsequent mixing of microbial gas with thermogenic gas and condensates is widespread. However, biodegradation has prevented precise determination of the fraction of thermogenic hydrocarbons present in gas samples. Reservoir sandstones were deposited within a deep‐marine channel belt along the axis of the North Alpine Foreland Basin, and reservoir quality depends on the precise position within this belt. In the study area, gas is trapped in compaction anticlines or at channel margin pinch‐outs and additional traps are formed by imbrication structures.

New data on Amynodontidae (Mammalia, Perissodactyla) from Eastern Europe: Phylogenetic and palaeobiogeographic implications around the Eocene-Oligocene transition.

Amynodontidae is a family of Rhinocerotoidea (Mammalia, Perissodactyla) known from the late Early Eocene to the latest Oligocene, in North America and Eurasia. European Amynodontidae are very rare, and all remains belong almost exclusively to a single post—Grande Coupure genus from the Oligocene, Cadurcotherium. The “Grande Coupure” defines an extinctions and dispersal-generated originations event in Europe that is nearly contemporaneous with the Eocene-Oligocene transition. Perissodactyls are one of the major groups affected by this event: Palaeotheriidae went almost extinct during this crisis, whereas Rhinocerotidae appeared for the first time in Europe. Study of fossiliferous Eastern-European localities from this age is crucial for the understanding of this crisis. We report here three new localities of Amynodontidae in Eastern Europe. Two of them are dated from the Eocene (Morlaca, Romania; Dorog, Hungary), whereas the other is either Late Eocene or Early Oligocene (Dobârca, Romania). The skull from this latter locality belongs unexpectedly to the same individual as a previously described mandible attributed to “Cadurcodon” zimborensis. As a result, this specimen can be allocated to its proper locality, Dobârca, and is assigned to a new genus, Sellamynodon gen. nov. It is characterised by an extraordinary growth of the nuchal crest, a unique character among amynodontids. Along with this remarkable material from Dobârca, two specimens from another Romanian locality, Morlaca, have been recently discovered and are dated from the Late Eocene. They belong, as well as new material from Dorog (Middle Eocene, Hungary), to the genus Amynodontopsis, also found in North America. The new Hungarian material represents the earliest occurrence of Amynodontidae in Europe. New phylogenetic hypotheses of Rhinocerotoidea are proposed, including the new material presented here, and show that Amynodontidae may be closer to the polyphyletic family ʽHyracodontidaeʼ than to Rhinocerotidae. Amynodontidae, with their deep preorbital fossa and extremely reduced premolars, display in fact a very derived condition, compared to rhinocerotids.