Fossiliferous Horizons Research Articles

Conodonts suggest a late Spathian (late Early Triassic) age for Thaisaurus chonglakmanii (Reptilia: Ichthyosauromorpha) from Thailand

The timing of the emergence of marine reptiles following the Permian–Triassic mass extinction is crucial for studying the recovery of marine ecosystems in the Triassic. Conodonts, key index fossils in the Triassic, are widely used to date the marine reptiles, especially in the Early Triassic. Triassospathodus anhuinensis is a conodont species originally discovered in the upper Spathian of South China, but lacked a comprehensive description, leading to misidentifications and confusion in previous research. Here, we reevaluated Tr. anhuinensis and summarized its morphological characteristics and spatial and temporal distribution based on a review of the literature. We then critically evaluated the age of the primitive ichthyosaur Thaisaurus chonglakmanii from Thailand based on the updated knowledge of Tr. anhuinensis. We sampled the Khao Thong section where T. chonglakmanii was found for conodont study. Tr. anhuinensis elements were obtained from the bed where T. chonglakmanii was collected and also in the bed five metres above the T. chonglakmanii fossil horizon, suggesting a late Spathian age for T. chonglakmanii. A late Spathian age for T. chonglakmanii questions the hypothesis of Thailand as the place of origin of ichthyosaurs in the late Induan or early Spathain.

A paleoenvironmental and ecological analysis of biomarkers from the Eocene Fossil Basin, Green River Formation, U.S.A.

Exceptionally well-preserved fossil specimens in the Fossil Basin of the Green River Formation (GRF) have made it the subject of extensive paleontological study, but the organic molecular framework that evolved during a key paleoclimatic and fossil-bearing interval during the early Eocene is poorly understood. Whereas the organic geochemistry of the larger co-eval GRF basins has been extensively characterized, our molecular understanding of the fossil-bearing layers in the Fossil Basin and the drivers of the exceptional fossilization therein remain unresolved. To bridge this gap, sediments from the famous 18″-layer — the fossiliferous horizon that is extensively quarried for exceptional soft-tissue fossils — were sampled for organic and isotopic geochemical characterisation. The results show that the Fossil Basin sedimentary archive is geochemically distinct from other GRF basins, as exemplified by the absence of the classical biomarker β-carotane and minimal evidence for the large green algal blooms that predominate in the other GRF lake basins. Photic zone euxinia (PZE), anoxia, and a freshwater cap enabled development of a productive and diverse ecosystem. Salinity and density stratification prevented vertical mixing of the water column and supported preservation of decaying carcasses. In contrast to other GRF basins, the small areal extent and ellipsoid shape of the Fossil Basin focussed terrestrial and freshwater inputs into the lake, resulting in ideal conditions for preservation of an exceptional fossil record.

A new Gondwanan perspective on the Jurassic-Cretaceous transition from the Tithonian-Berriasian interval of southeastern Morocco

Knowledge of continental faunas and floras from the Jurassic–Cretaceous transition in Gondwana, and especially in Africa, is limited. Here, we report the discovery of a rare assemblage of plants and aquatic reptiles from the Tithonian–Berriasian interval of the Anoual syncline in southeastern Morocco. Our preliminary field investigations led to the discovery of a disarticulated skeleton of a goniopholidid crocodylomorph, of a single fragment of a turtle plate, and of abundant plant remains, inviting further exploitation of the fossiliferous horizon. This assemblage indicates a freshwater habitat bordered by a lush moist conifer forest. Its taxonomic composition shows a strong similarity with better known contemporaneous Laurasian assemblages and stresses the paucity of coeval Gondwanan assemblages. Our discovery highlights that peri-Tethys continental assemblages may have shared common taxa and raises the question whether Laurasian and Gondwanan taxa from the Jurassic-Cretaceous transition were cosmopolitan, before they diverged later during the Cretaceous.

The history of palaeontological research and excavations at Monte San Giorgio

There is a long history of palaeontological excavations at Monte San Giorgio (Switzerland) and the adjoining Monte Pravello—Monte Orsa (Italy), aimed at finding well-preserved skeletons of Middle Triassic vertebrates. The first fossils were discovered in the mid-Nineteenth Century during mining of black shales (scisti bituminosi) near Besano, Italy, with further finds in the early Twentieth Century through industrial-scale mining. Studies of the material generated international interest and prompted formal palaeontological excavations on both sides of the border. The earliest excavations took place in 1863 and 1878, with the most extensive between 1924 and 1968. Systematic excavations have continued up to the present day, focusing on six distinct fossiliferous horizons: the Besano Formation and the overlying Meride Limestone with the Cava inferiore, Cava superiore, Cassina, Sceltrich and Kalkschieferzone beds. All these have provided material for study and display, with Monte San Giorgio itself recently designated a UNESCO World Heritage Site. The workers and organisations involved, locations excavated and material recovered are described herein.

First results of the biostratigraphy and geochronology of the classic Nihewan Fauna, China

The Nihewan Basin is infilled by a relatively complete Pliocene to Pleistocene sequence, rich mammalian fossils and containing many Palaeolithic artefacts, implying that it is a unique location for Quaternary multidisciplinary study. Fossil excavations in these deposits have been carried out for nearly a century. The systematic study of the fossils by Teilhard de Chardin and Piveteau in 1930 laid the foundations for the classic Nihewan Faunal assemblage, which has been widely followed as a standard for the Early Pleistocene biochronology in eastern Asia. With the availability of magnetostratigraphic analyses on several sections in the Nihewan basin, a comprehensive geochronological study is timely pending. Here we report the results of a comprehensive survey of the Xiashagou section, where the classic Nihewan Fauna was discovered. By synthesising the lithostratigraphical, biostratigraphical, and magnetostratigraphical information, together with measurements taken by the authors, the total thickness of the Nihewan Formation in the Xiashagou section being 116 m. Furthermore, the geochronological study demonstrates that the classic Nihewan Fauna was originally recovered from at least 6 fossil horizons, spanning from ∼2.4 Ma to ∼1.8 Ma, i.e., the early Early Pleistocene. The new evidence from the Xiashagou section also suggests several cycles of fluctuations in the biodiversity and population of the classic Nihewan Fauna during the early Pleistocene. The preliminary correlation of these cycles matches the short periods of glaciation in the early Pleistocene.

Floral Diversity of South Karanpura Basin, Jharkhand, India and their Palaeoclimatic Implication with Special Reference to Palaeoenvironment

Abstract The palaeofloristic study of Gondwana sediments recovered from Religara area, South Karanpura Basin illustrates the macrofloral diversity in the area. Three distinct megafloral assemblages I, II, III are reported from freshly exposed coaly shale and carbonaceous shale layers of lower Barakar, upper Barakar and Raniganj formations of the basin. The assemblage comprises 72 species and thirteen genera of which 28 are newly reported species, which clearly exemplifies the macrofloral diversity over Permian Period in the studied area. The retrieved floral assemblages justified the existence of two interrelated ecosystems i.e., terrestrial and marshy. A gradual shifting of leaf morphology in reticulate leaves of order Glossopteridales illustrates biostratigraphic age as well as the shifting of climate during the deposition of sediments. The dominance of narrow mesh Glossopteris flora with the presence of typical Karharbari flora in the lowermost fossil horizon, illustrating the biostratigraphic age as late Artinskian (lower Barakar Formation). Likewise, the middle and upper floristic zones are dominated by Glossopteris of intermediate mesh form and broad mesh form suggesting biostratigraphic age as Kungurian (upper Barakar) and Wordian-Changhsingian (Raniganj) respectively. Deposition of in-situ Vertebraria depicts the autochthonous coal deposits and existence of some patches of palaeosol in the investigated location. The present investigation aims to infer the biostratigraphy, palaeoclimate, palaeoenvironment, palaeovegetational reconstruction of the basin during late Artinskian –Kungurian and Wordian- Changhsingian times.

Emergence and ecological transition of the Mesozoic marine reptiles: Evidence from the Early Triassic Chaohu and the Middle Triassic Xingyi Faunas

Two major evolutionary events in the early history of Mesozoic marine reptiles have been recorded in the Triassic of China. The first event evidenced by the Early Triassic Chaohu Fauna was the emergence of new marine communities and their subsequent radiation in the Spathian Subage of the late Olenekian (Early Triassic). The earliest marine reptile fossil horizon was found to be 248.81 Ma in age, therefore about 3.35 myr after the end-Permian mass extinction. The emergence time for the clade Ichthyosauromorpha has been suggested to be between 251.5 and 248.8 Ma. Moreover, the first occurrence of this clade is not thought to have been prior to the end-Permian mass extinction and this is therefore indicative of an exceptionally high evolutionary rate. Globally, twenty eight marine reptile species (six from Chaohu) have been recorded in an interval of just 2 myr in the Early Triassic, and these marine reptiles diversified and became the predators in the Mesozoic marine ecosystems that formed soon after the end-Permian mass extinction. The first event was followed by a transition from coastal to oceanic communities followed by selective disappearance of coastal species and emergence of oceanic species in the Ladinian of the Middle Triassic, as evidenced by the Xingyi Fauna. Here a 5.1 m thick fossiliferous unit yields 17 or more taxa of marine reptiles and can be subdivided into two separate assemblages. The lower assemblage is mainly composed of nearshore sauropterygians, close to that of the Anisian Panxian Fauna and with a strong palaeobiogeographic affinity to western Tethys. In the upper assemblage, the coastal pachypleurosaurian and nothosaurian sauropterygians disappear, to be replaced by the large ichthyosaurs and pistosaurs with a closer palaeobiogeographic affinity to Panthalassa. In this assemblage, there is an example of an ichthyosaur unequivocally feeding on another marine reptile. This is the oldest definitive record of a marine reptile acting as an apex predator. The transition from the lower assemblage to the upper one also records a turnover of Mesozoic marine reptiles from coastal to oceanic forms, and from a strong west Tethyan affinity to an assemblage showing a greater affinity with east Panthalassa by the late Middle Triassic.

Pliocene volcanic terrain of the South Caucasus as a missing link in Eurasian palaeobiogeography: Dating and palaeoenvironments of vertebrate assemblages of the Jradzor locality, Armenia

Cenozoic faunal exchanges between Europe, Asia, Africa and America played a key role in shaping modern-day Eurasian ecosystems with dispersal pathways controlled by the dynamics of natural palaeogeographic barriers (e.g., deserts, isthmuses, large water bodies, etc.). The South Caucasus is a mountainous region between Asia and Europe, which served as an important dispersal route during the late Cenozoic for the intercontinental exchanges of diverse terrestrial vertebrates. The Pliocene geology of this region is dominated by volcanic and volcaniclastic deposits that are generally not favourable for fossil preservation. However, a few rich fossil vertebrate faunas do occur although they lack comprehensive palaeoenvironmental and age constraints. In this paper, we present an integrated study of the stratigraphy and palaeontology of the Jradzor section located in the Gegham volcanic province of Armenia, to improve knowledge of late Cenozoic dispersal pathways. The 57-m-thick succession comprises 19 fossiliferous horizons with at least 48 identified vertebrate taxa (excluding birds). The palaeoenvironmental reconstruction suggests that the succession was deposited within a short-lived dammed lake that was subject to pyroclastic density flows, and later evolved into soil catenas. Taphonomic observations indicate that pyroclastic flows caused a high mortality of small-size vertebrates in most fossiliferous horizons, while a catastrophic lahar buried the large vertebrate fauna. Multiproxy dating places the studied section between 4.3 and ∼ 3.03 Ma and the mammalian fauna correlates to the MN15. Comparison with similar age localities from across the region shows that Jradzor comprises the most continuous Pliocene succession with the highest number of fossil taxa and fills the MN15 interregional gap. The rich fossil vertebrate faunas have Asian and primarily European affinities. Findings show that the South Caucasus was a significant dispersal route for terrestrial vertebrates between Europe, Asia and Africa, and is of crucial importance for understanding Eurasian palaeogeography.

New evidence for the unique coexistence of two subfamilies of clawed perissodactyls (Mammalia, Chalicotheriidae) in the Upper Miocene of Romania and the Eastern Mediterranean

Chalicotheres are a peculiar group of large herbivorous mammals, closely related to extant tapirs, rhinoceroses, and horses, but with large claws instead of hooves. The family Chalicotheriidae consists of two subfamilies, the Schizotheriinae and the Chalicotheriinae. Herein we present chalicothere remains from the Upper Miocene locality of Pogana 1 in Romania, identifying the schizotheriine Ancylotherium pentelicum and an indeterminate chalicotheriine that were both found in the same stratigraphic layer. Thus, the Pogana 1 locality represents one of the very few confirmed cases of the co-occurrence of the two subfamilies within one fossiliferous horizon in the same fossil site. A detailed review of all localities where the two subfamilies have been reported to co-occur shows that this is a rare phenomenon that is almost exclusively observed in the Turolian of the Balkan-Iranian zoogeographical province. This is probably due to provincial differences in the palaeoenvironment. The data presented here support the hypothesis of a diverse mosaic environment in the Balkan-Iranian province with both closed environments and open habitats that was able to sustain a rich and diverse large mammal fauna.

Rediscovery and stratigraphic calibration of the classic Nihewan Fauna, Hebei Province, China

The classic Nihewan Fauna, as the representative of early Pleistocene Asian Land Mammal Age Nihewanian, has long been cited for bio- and chronostratigraphic correlation. However, its precise provenance and stratigraphic horizon have remained unsolved till now. The authors successfully extracted the vital information by rediscovering 30 of the original excavation localities. The fossils were catalogued with their provenance through an extensive field survey and comprehensive inspection of the Tianjin Natural History Museum collection. A review of the original description of these fossil localities, using satellite images, and subsequent lithological examination of the Xiashagou strata in the field verified the new findings. The survey produced the first stratigraphic profile calibrated with fossil horizons of the Nihewan formation in the Xiashagou section. Correlated with the published magnetostratigraphical profile of the section, an age of ∼2.4–1.8 Ma is estimated for the classic Nihewan Fauna.

Re-evaluation of the morphology and phylogeny of Diplocynodon levantinicum Huene & Nikoloff, 1963 and the stratigraphic age of the West Maritsa coal field (Upper Thrace Basin, Bulgaria).

Diplocynodon levantinicum Huene & Nikoloff, 1963 was described based on few bone fragments from the West-Maritsa lignite basin of Central Bulgaria. Huene & Nikoloff, 1963 assumed a late Pliocene age, implying that this species represents the stratigraphically youngest crocodilian of Europe. In this current study, we re-evaluate the stratigraphy of the West-Maritsa Basin and conclude a late Oligocene age of ~26 Ma for the Kipra coal-seam, the fossiliferous horizon. Furthermore, topotypical and undescribed D. levantinicum specimens are accessible now and allowed for a deeper taxonomic and phylogenetic analysis. A comparison with other Diplocynodon species reveals D. levantinicum as a valid species, having (1) a long suborbital fenestra, (2) a very short dentary symphysis, (3) a large gap between the first and second dentary alveolus, (4) an occlusion pit in line with the tooth row posterior to the 14th dentary alveolus, (5) a sulcus lateral to the glenoid fossa and, (6) a lingual foramen for the articular artery situated entirely on the surangular. The phylogenetic analyses find D. levantinicum deeply nested inside the Diplocynodontinae subfamily. After the disappearance of the Paratethyan influence (Solenovian regional stage) in the Upper Thrace Basin this species has roamed during the late Oligocene extensive freshwater lake and swamp ecosystems represented by the Maritsa Formation. Diplocynodon levantinicum represents the only nominal Diplocynodon taxon of late Oligocene (Chattian) age.

Lithostratigraphy, chronostratigraphy, and sedimentary environments of the middle Miocene Quebrada Honda Basin in southern Bolivia and implications for Andean climate and uplift

The late middle Miocene Quebrada Honda Basin of southern Bolivia has long been studied for its diverse fossils of terrestrial vertebrates and, more recently, for its record of paleoelevation and paleoclimate in the Eastern Cordillera of the Andes Mountains. This paleobiological and paleoenvironmental archive is constrained by high resolution radioisotopic ages linked to paleomagnetic reversal stratigraphy in multiple areas within the basin. Nevertheless, studies of the basin's stratigraphy have been limited and questions remain about how the sedimentary deposits and fossil horizons in different parts of the basin relate to each other. We confirm the identification of three lithostratigraphic units, show that the units extend across the basin, and examine the distribution of sedimentary and pedogenic facies and volcanic tuffs within them. We identify different styles and stages of pedogenic development that correspond to mappable differences in outcrop character. Volcanic tuffs and sedimentary and pedogenic facies exhibit high lateral continuity consistent with accumulation on a low relief basin floor. In contrast, sedimentary and pedogenic features change vertically over multiple scales reflecting secular variations in aridity and stability over seasonal to multimillennial scales. Erosional truncation of lithostratigraphic units and a ~ 700,000-year gap in the ages of superimposed strata delineate an erosional unconformity with >50 m of relief that was cut ~12 million years ago. Breach of the basin margin along a boundary between local structural blocks may account for the development of localized incision during a period when landscapes of the Eastern Cordillera were stable with little deformation or erosion. Regional landscape stability at that time has been attributed to low elevation or a position behind an orographic precipitation barrier. The sedimentary and pedogenic facies, faunal communities, and intraformational unconformity of the Quebrada Honda Basin favor a low elevation setting, which has implications for the timing and mechanisms of uplift of the Bolivian Andes.

Alkenones in Pleistocene Upper Bed I (1.803–1.900 Ma) sediments from Paleolake Olduvai, Tanzania

The Olduvai Gorge Coring Project (OGCP) recovered sequences of Pleistocene lake sediments that correlate with those known from outcrops directly associated with hominin fossil horizons. The sedimentary succession from Core 2A (02° 58′ 43′' S, 035° 19′ 25.5′' E), which targeted the ancient lake-basinal depocenter, includes stratigraphic intervals (∼1.86 Ma) sandwiched between the Bed I basalt and Tuff IF dated horizons, where remains of two hominin holotypes have been recovered. The lower part of this sequence (72.3–86.9 mbs) consists of lacustrine claystones interbedded with sandy claystones characterized by high Corg (av. 2.5%) and includes several laminated intervals. It displays shifts in terrestrial vegetation recorded by values for δ13CTOC and δ2HnC31 that reflect changes in the proportions of C3 vs C4 plants and precipitation, respectively. These temporal profiles represent higher-resolution signatures of the precession-scale wet/dry cycles previously recognized in the outcropping sedimentary succession of Olduvai Gorge. Several samples from this interval contain alkenones comprising C37 and C39 alkadien-2-ones and alkatrien-2-ones, and C38 and C40 alkadien-3-ones and alkatrien-3-ones. They are distinguished from the vast majority of alkenone distributions reported in lake sediments from polar and temperate latitudes (e.g., Greenland, N. and S. America, Europe, Russia, China, S. Africa, Antarctica) by the absence of tetraunsaturated alkenones (e.g., C37:4). The alkenone distributions vary stratigraphically with higher concentrations in the drier intervals of the precession-scale cycles that exhibit characteristics resembling those of Group II haptophytes found in contemporary saline/alkaline environments rather than those of Group I haptophytes from freshwater ecosystems. Paleolake Olduvai represents the first reported occurrence of alkenones in a low-latitude Pleistocene lake, where the absence of alkatetraenones may reflect contributions from strains of Group II haptophytes that are favored by warmer temperatures or saline conditions. Temporal variations in unsaturation indices (U37K', U38K') and the proportions of alken-2-ones and alken-3-ones likely reflect influences on alkenone production by haptophytes that are associated with changes in the lake environment primarily driven by hydrologic cycles (e.g., salinity and alkalinity) rather than lake temperatures.

A fossil assemblage from the mid-late Maastrichtian of Gavdos Island, Greece, provides insights into the pre-extinction pelagic ichthyofaunas of the Tethys.

The global body-fossil record of marine 'fishes' from the time interval immediately preceding the Cretaceous-Paleogene Extinction is markedly poor. This deficiency appears to be further exacerbated with regards to offshore and deep-water taxa, obscuring our understanding of the state and composition of corresponding vertebrate faunas at the onset of this major extinction event. Recent fieldwork in the mid-late Maastrichtian exposures of the Pindos Unit in Gavdos Island, Greece, yielded a small but informative sample of fossil 'fishes', which inhabited the Tethys approximately three to four million years before the extinction. In this work we describe this sample, which comprises between eight and nine discrete morphotypes of various size classes, belonging to †Ichthyodectoidei, Aulopiformes (†Dercetidae, †Enchodontidae, †Ichthyotringidae), cf. †Sardinioididae, as well as the hexanchid shark †Gladioserratus sp. The new material expands the faunal list for the Maastrichtian of Gavdos Island, and the Pindos Unit as a whole, and further allows for the description of a new genus and species of †Enchodontidae and a new species of †Ichthyotringidae. The two new taxa are found to be widespread in the Maastrichtian of the Pindos Unit. The overall character of the assemblage agrees with previous interpretations of an offshore and rather deep depositional environment for the fossiliferous horizons. Furthermore, it exhibits a higher diversity than, and little taxonomic overlap with penecontemporaneous teleost assemblages from the Tethys, and informs on the otherwise poorly known Maastrichtian offshore and deep-water marine ichthyofaunas of the region.

Ostracod Response to a Major Middle Jurassic Sea-Level Fall: A Case Study from Southern Tunisia (North Gondwana) with Implications on Regional Stratigraphy and Palaeoenvironmental Reconstruction

Marginal-marine to non-marine ostracod assemblages from the Bajocian (Mid-Jurassic) of southern Tunisia, precisely from the Krachoua Formation at the Kef El Anneba section near the Beni Kheddache area, are here described and tested for their utility to improve the stratigraphic accuracy and palaeoenvironmental reconstructions. This particular microfauna consists of 11 species belonging to 6 genera and represents 2 distinct types of species-rich assemblages from this time interval, allowing the interpretation of the depositional setting of the fossiliferous horizon from which the samples derive. The first ostracod assemblage is mainly composed of the brackish to shallow marine species Fastigatocythere sp. Mette, 1995; Vernoniella aff. V. bajociana Bate, 1965b; Paracypris sp. A, Paracypris sp. B, Fabanella sarda Malz et al., 1985; Marslatourella aff. M. bathonica Andreu, 1999; and Fabanella aff. F. bathonica Oertli, 1957. This ostracod biofacies reflects marginal marine (shallow platform, restricted lagoon) conditions in the studied area. In contrast, the second ostracod assemblage is exclusively dominated by the non-marine limnic species Alicenula sp., Theriosynoecum pusilla Rohr, 1976; Theriosynoecum aff. T. aveyronensis Rohr, 1976; and Theriosynoecum sp. Such ostracod biofacies reflects the establishment of (a) permanent freshwater lake(s) in the studied area, triggered by the total emersion of the Bajocian Krachoua platform, presumably as response to the short-term sea-level fall event JBj3 of Haq (2017). The recognized ostracod species from the upper part of the Krachoua Formation at Kef El Anneba section (Medenine area) are particularly similar to those already described from the neighbouring sections of Kezzani (Dhaher area) and Krachoua (Tataouine area), facilitating a stratigraphic calibration of the Krachoua Formation, as well as regional correlations of the respective Bajocian continental event within the southern Tunisian palaeogeographic domain. Moreover, the biogeography of the studied ostracod microfauna from the Mid-Jurassic of southern Tunisia provides further arguments to support the hypothesis of significant biological exchanges between Laurasian and Gondwanan islands, as recently demonstrated by means of a charophyte microflora, indicating that Peri-Tethyan biogeography remained relatively uniform during that time interval and challenging the previous assumption of their endemism.

New geochronological constraints for the Lower Cretaceous Jiufotang Formation in Jianchang Basin, NE China, and their implications for the late Jehol Biota

The Lower Cretaceous Jiufotang Formation in western Liaoning Province, northeastern China contains important vertebrate fossils of the late Jehol Biota, e.g., the four-winged non-avian dinosaur Microraptor . This formation documents the late phase of the Jehol Biota, producing the most abundant fossil records of the Mesozoic birds. However, the precise age constraints on the fossiliferous layers of this formation remain scarce and chronological consensus of this formation has not been reached, limiting our understanding of the evolutionary history of the Jehol Biota and its time-spatial distribution. Here we present secondary ion mass spectrometry (SIMS) U-Pb zircon analysis results of four tuff samples interbedded within the Jehol fossil-bearing layers from the Jiufotang Formation outcrops at the Sanmendian and Xiaotaizi sections in the Jianchang Basin, western Liaoning. Stratigraphic correlation between two outcrop sections is achieved by combining lithostratigraphic, biostratigraphic, and SIMS U-Pb zircon dating results. One tuff bed SMD17-1 closed to the boundary of the Yixian/Jiufotang formations from the Sanmendian section yielded an age of 122.0 ± 0.9 Ma, and three tuff beds XTZ17-1, XTZ17-2, and XTZ17-3 from the Xiaotaizi section dated to 118.9 ± 0.8 Ma, 118.8 ± 0.6 Ma, and 118.6 ± 1.1 Ma, respectively. These ages suggest that the Jiufotang Formation in Jianchang Basin was deposited at ca. 122.0–118.9 Ma, the latest Barremian–Aptian stage of the Lower Cretaceous and provides stringent constraints on the Mesozoic vertebrates discovered in the Jianchang Basin. Furthermore, the late Jehol Biota documents in the Jiufotang Formation has been placed between ~123 and ~119 Ma based on our new chronology and previous radiometric dates. It is critical to evaluate the evolutionary history of various important Mesozoic taxa discovered from the Jehol Biota and explore the patterns and modes of major vertebrate lineages documented in this interval. • • We report a new chronology from the Jiufotang Formation in Jianchang Basin, NE China. • • The fossiliferous horizons have precisely constrained to 122.0–118.9 Ma. • • Age calibration for the diversification of mammals and birds of late Jehol Biota. • • Updated age of the Jiufortang Formation for Palaeobiology Database ( paleodb.org /).

An atypical Burgess Shale-type fossil assemblage from Cambrian Stage 4 of the Jingshan area, South China: Taphonomy, palaeoecology, and global correlations

Burgess Shale-type biotas have been widely reported from the Cambrian in North America, Siberia, Greenland, China, and Australia; they are crucial in reconstructing the biotic evolution and ecological interactions of early metazoans. Here, we report an atypical Burgess Shale-type fossil assemblage from the Shilongdong Formation (Cambrian Stage 4) in the Jingshan area, central Hubei Province, South China. The newly recovered fauna is preserved in a nearly two-meter-thick yellowish-green shale unit intercalated within the massive dolomite and dolomitic limestone succession of the upper Shilongdong Formation. The fossil-bearing shale unit is likely deposited in the deep subtidal zone below storm wave base with occasional influence of weak storm flows, which was likely situated in the relatively low location with the interior of the restricted carbonate platform. The presence of the trilobite Redlichia guizhouensis assigns the Jingshan fossil assemblage to the Longwangmiaoan Stage (Cambrian Series 2, Stage 4), which is of similar age to the Jianhe biota, but younger than the Guanshan, Balang, and Shipai biotas, and slightly older than the Kaili biota, South China. The Jingshan assemblage is fossiliferous, containing common shelly and some soft-bodied fossils. It comprises algae, brachiopods, arthropods, hyoliths, priapulid worms, echinoderms, possible cnidarians, molluscs, and some enigmatic organisms. The fossils retain soft parts, including brachiopods with pedicles and delicate setae, a naraoiid with the antenna preserved and digestive tracts. The diversity of the assemblage is limited compared with better-known biotas of similar age, but investigation is at a preliminary stage. It is an important geographical extension of the Burgess Shale-type biotas in China and provides more information about the Cambrian Explosion of life and biodiversity by comparing fossiliferous horizons in a chronological framework.

A Lower Cretaceous palynoflora from Carregueira (Lusitanian Basin, westernmost Iberia): taxonomic, stratigraphic and palaeoenvironmental implications

Here we describe a new Lower Cretaceous palynoflora from the Lusitanian Basin, located in the westernmost sector of the Iberian Peninsula. The spore-pollen assemblage was extracted from samples collected in the Carregueira clay pit complex, located near the village of Juncal, western Portugal, from sedimentary deposits belonging to the Figueira da Foz Formation. A rich and well-preserved palynoflora, typical of non-marine fluvial environments, was recovered. Fifty-eight species and morphological groups of palynomorphs in 43 genera were recognized. The palynoflora is dominated by fern spores and conifer pollen. Angiosperm pollen is scarce and mainly represented by Afropollis, Clavatipollenites, Stellatopollis and Senectotetradites. Comparisons with described marine sections in Portugal suggest that the fossil horizon is lower Albian, corresponding to a hiatus between Zone I and Zone II in the Potomac Group of the eastern USA. The same beds contain a mesofossil flora dominated by angiosperm seeds, fruits and flowers. A similar contrast in the relative abundance of angiosperm mesofossils and pollen is seen at other Portuguese localities but is not evident in the Potomac Group. The palynoflora and the sedimentological data suggest deposition in wet lowland environments in a moderately humid regional setting.

Phyllozoon and Aulozoon: key components of a novel Ediacaran death assemblage in Bathtub Gorge, Heysen Range, South Australia

AbstractThe recognition of fossiliferous horizons both below and above the classical Ediacara levels of the Flinders Ranges, South Australia, significantly expands the potential of this candidate World Heritage succession. Here we document a small window into the biology and taphonomy of the late Ediacaran seafloor within the new Nilpena Sandstone Member of the Rawnsley Quartzite in Bathtub Gorge, northern Heysen Range. A 1 m2 slab extracted from the gorge, now on permanent display at the South Australian Museum, has a death assemblage dominated by the erniettomorph Phyllozoon hanseni Jenkins and Gehling 1978 and a newly named macroscopic tubular body fossil – Aulozoon soliorum gen. et sp. nov. – on its fine sandstone bed sole. The orientations and juxtaposition of these taxa suggest overprinting of an in situ benthic Phyllozoon community by sand-filled tubes of Aulozoon carried in by a storm wave-base surge. Phyllozoon hanseni is a widespread species that is restricted to the Nilpena Sandstone Member of the Rawnsley Quartzite, whereas Dickinsonia costata ranges from the underlying Ediacara Sandstone Member into the Nilpena Sandstone Member. Fundamental differences in the ways these two vendobiont taxa are constructed and preserved may provide insights into their biology and phylogenetic affinities. In the Nilpena Sandstone Member, D. costata is joined by Dickinsonia rex Jenkins 1992, which appears to be confined to the member, and is here re-described to clarify its taxonomic status and stratigraphic distribution.

The fossil aardvark Amphiorycteropus gaudryi (Forsyth Major, 1888) from the late Miocene of Kerassia (Euboea, Greece)

ABSTRACT Remains of the fossil aardvark Amphiorycteropus gaudryi (Orycteropodidae, Tubulidentata) from the late Miocene locality of Kerassia in Greece are here described and compared with material of other orycteropodid species. The studied material includes a partially preserved skull, two mandibular fragments, two lumbar vertebrae, the first rather complete sacrum of the species and some appendicular skeletal remains. The new material reveals noteworthy information on the diagnostic characteristics of the species, such as the variable morphology of the foramen magnum. Furthermore, we comment on some ecomorphological features associated with the fossorial habits of A. gaudryi and discuss its tail length. Lastly, the biogeographical distribution of the species is examined. Emphasis is given to its noticeable absence in the classical locality of Pikermi (Attica) and its presence on Samos Island, at a slightly younger age. In Kerassia, A. gaudryi does not occur in the lower fossiliferous horizon, but only in the stratigraphically younger, upper horizon. Since A. gaudryi is known from MN11 to MN13, its exclusive occurrence in the upper fossiliferous horizon of Kerassia could be connected to spatial and temporal environmental changes of the Eastern Mediterranean during the late Miocene.