Evolution of pelagic swells from hardground analysis (Bathonian–Oxfordian, Eastern External Subbetic, southern Spain)

The Middle Bathonian to Middle Oxfordian interval in the Eastern External Subbetic (Betic Cordillera, SE Spain) is characterized by Ammonitico Rosso facies including various stratigraphic breaks. Five hardground-bounded units are recognized in relation to hiatuses in the ammonite record at the following stratigraphic boundaries: Hg1 (Lower–Middle Bathonian), Hg2 (Middle–Upper Bathonian), Hg3 (Lower–Middle Callovian), Hg4 (Middle–Upper Callovian), and Hg5 (Callovian–Oxfordian). Interesting features of these hardgrounds include their microfacies, ferruginous crusts and macro-oncoids, taphonomy of macroinvertebrates, trace fossils, neptunian dykes, and the hiatuses associated with each of them. The main hardgrounds (Hg1, Hg2, and Hg5) contain trace fossils of the Cruziana and Trypanites ichnofacies as well as abundant fossil macroinvertebrates with taphonomic features evidencing corrasion, early diagenesis, and reworking, indicating substrate evolution from softground to hardground. Neptunian dykes affected the trace fossils and ammonoid moulds, and their walls and the hardground surfaces were colonized by ferruginous microbial crusts. These features are characteristic of the External Subbetic pelagic swells, where the absence of sedimentation, sediment bypassing and erosion, and early diagenesis during relative sea-level falls produced hardgrounds. The neptunian dykes are indicative of tectonic activity in the areas of pelagic swells. Ferruginous crusts and macro-oncoids developed only on hardground surfaces and neptunian dykes walls prior to deposition of condensed bioclastic beds, which are interpreted as the first deposits after hardground development and are related to the onset of transgression. The varying ranges of the gaps as well as lateral facies changes are related to different local paleobathymetry controlled by the activity of listric faults.     

The genus Kepplerites Neumary et Uhlig (Kosmoceratidae,Ammonoidea) in the Bathonian-Callovian beds (Middle Jurassic) of the Russian Platform

The succession of early species of the genus Kepplerites is established in the Upper Bathonian-Lower Callovian beds of Central Russia and compared with the ammonoid succession of East Greenland and Western Europe. Late Bathonian members of the genus Kepplerites from the Middle Volga Region are generally similar, though not identical to those from Greenland, whereas the Early Callovian Kepplerites species and their immediate Bathonian ancestors are represented by species common to all three regions. The analysis of the ammonoid distribution suggests a connection between the East Greenland and Central Russian marine basins in the Early and Middle Bathonian and in the Early Callovian, and their short-term isolation in the Late Bathonian. A new species, Kepplerites (Kepplerites) aigii sp. nov., is described from the Upper Bathonian (keuppi Zone) of the Alatyr River basin (Middle Volga Region).     

Middle Jurassic (upper Bajocian) marine vetigastropods from the Western Saharan Atlas,Algeria

Whereas Middle Jurassic gastropods are very well known in Europe and other regions of the world, these faunas have been much less studied from northern Africa and most contributions available in literature have been based on relatively well-preserved material. Except a little lower Bajocian fauna from the Central High Atlas (Morocco) described at the turn of the 21th century, nothing is known about the Middle Jurassic gastropods of the southwestern Tethyan margin. The present paper aims to update the systematics of two vetigastropod species: Obornella cf. granulata (Sowerby, 1818) and Ambercyclus ornatus (Sowerby, 1819) recently found in the upper Bajocian succession of the Ksour Mountains (Tniet el Klakh Formation) at western Saharan Atlas (northern Algeria). The new Ambercyclus material found in well-preserved conditions confirms the absence of umbilicus in Ambercyclus; thus, we emend the original generic diagnosis. The specimens of Obornella cf. granulata and Ambercyclus ornatus represent the first occurrence of both genera and species in the upper Bajocian marine deposits of the western Saharan Atlas, and provide new taxonomic and palaeobiogeographic information about Middle Jurassic vetigastropods in Algeria.     

Middle Jurassic trace fossils from the Ridang Formation in Sajia County,South Tibet,and their palaeoenvironmental significance

An ichnofauna consisting of 18 ichnospecies (one of them new) in 14 ichnogenera are described for the first time from the Middle Jurassic Ridang Formation in Sajia County, South Tibet. The ichnofauna can be subdivided into two ichnoassemblages in ascending stratigraphic order: the Palaeophycus–Megagrapton ichnoassemblage in the lower and middle parts of the Ridang Formation, followed by the Cosmorhaphe–Nereites–Paleodictyon ichnoassemblage in the upper Ridang Formation. Overall, the trace fossils occur in a middle–distal turbidite fan sequence, as evidenced by both sedimentological analysis and the composition of the trace fossils. Several subenvironments of the middle–distal fan system have been recognized on the basis of the spatial distribution of the trace fossils. Typically, the channel-fill deposits in the middle part of the turbidite fan lack trace fossils, the interchannel and upper channel-fill (levee) subenvironments of the middle turbidite fan contain abundant facies-crossing trace fossils, in contrast to the distal part of the turbidite fan where deep-water trace fossils are dominant. The ichnofauna is similar to typical flysch ichnofaunas from Europe and North America in characteristics, and is interpreted to represent a typical deep-sea Nereites ichnofacies. The presence of these deep-sea trace fossils therefore would suggest that a continental slope environment existed in southern Tibet during the Middle Jurassic and the study area was located in a slope-abyssal plain setting.     

Signs of predation in the Middle Jurassic of south-central Poland: evidence from echinoderm taphonomy

Distinct faunal aggregates are described from the Middle Jurassic (uppermost Bajocian/lowermost Bathonian and Middle Bathonian) clay deposits of Częstochowa area, south-central Poland. These aggregates are composed of molluscs (scaphopods, gastropods, bivalves, ammonites and belemnites), articulate brachiopods and echinoderms (asteroids, crinoids and echinoids). A large percentage of the fossils, especially bivalves, are fragmented, but some fossils are complete. Although most of the fossils are crushed and fragmented, they are still identifiable to at least the genus level. Thorough statistical analysis of taphonomic features indicates that the preservation of asteroid marginal plates is distinct from the ossicles derived from the host clays. The high frequency of bite marks and the good state of preservation suggest that the accumulations are the products of predation activities and most probably are the effect of regurgitation. Taking into account the rich and diverse fauna, the predator was a bottom-feeding generalist. Possible predators include palaeospinacid sharks, a tooth of which was collected from the same bedding surface, but not associated with regurgitated remains. Although the bite marks on the asteroid ossicles point to sharks as potential producers of regurgitates, other vertebrates, like durophagous pycnodontiform fish, cannot be excluded.     

On the earliest known occurrence of the Middle Jurassic ammonite genusReineckeia in the Upper Bathonian of Jumara,Kachchh, western India

Two specimens of the Middle Jurassic ammonite genusReineckeia (sensu lato) have been found in the lowest beds of the Pachchham (Patcham) Limestones exposed in the core of the Jumara Dome, Kachchh (Kutch), Gujarat, western India. The stratigraphy is described in detail and the age bracketed to lie between latest Late Bathonian and Middle Bathonian, older than any previously described examples of this genus, either in India or in Europe (middle Early Callovian). The new finds are compared with other known pre-Callovian Reineckeiidae, notably those of the eastern borders of the Pacific, but the relationships are not close. The phylogenetic consequences are briefly discussed. The roots of the Reineckeiidae continue to lie hidden.     

Les empreintes de pas de Dinosauriens dans le Jurassique moyen du Haut Atlas central (Maroc): Nouveaux gisements et precisions stratigraphiques

Ten new Dinosaur foot prints fields have been discovered in Middle Jurassic red beds of Central High Atlas (Morocco). Ovoid prints (Sauropod) are there more common than tridactyle (Theropod). The trace fossils appear at two distinct levels of the red beds which have been previously rattached to Cretaceous.     

A lower jaw of Palaeoxonodon from the Middle Jurassic of the Isle of Skye,Scotland, sheds new light on the diversity of British stem therians

The Middle Jurassic was a key interval of mammalian evolutionary history that witnessed the diversification of the therian stem group. Great Britain has yielded a significant record of mammalian fossils from this interval, represented by numerous isolated jaws and teeth from the Bathonian of Oxfordshire and the Isle of Skye. This record captures a key period in early cladotherian evolution, with amphitheriids, peramurans and ‘stem zatherians’ displaying intermediate talonid morphologies that document the evolutionary assembly of tribosphenic molars. We present a mandible with near‐complete dentition from the late Bathonian (c. 167.4–166.5 Ma) Kilmaluag Formation, near Elgol, Skye, representing the amphitheriid Palaeoxonodon ooliticus, previously known only from isolated teeth. The specimen sheds new light on the taxonomic diversity of British Middle Jurassic stem therians, as the morphological variation within the preserved tooth row encompasses that previously ascribed to three distinct species within two genera: Palaeoxonodon ooliticus, P. freemani and Kennetheridium leesi. Thus, both P. freemani and K. leesi are subjective junior synonyms of P. ooliticus. The dental formula of P. ooliticus (i4:c1:p5:m5) is intermediate between the primitively larger postcanine count (p5:m6–7) of Amphitherium and the reduced number in peramurans and tribosphenidans (p5:m3). Phylogenetic analyses of P. ooliticus generally confirm a close affinity with Amphitherium, but highlight the lack of strong empirical support for hypothesized patterns of divergences among early cladotherians.     

Composite Trace Fossil Assemblage in a Distal Carbonate Setting from the Tethys (Middle Jurassic,Betic Cordillera,Southern Spain)

Ichnological analysis of a Middle Jurassic carbonate surface from the Betic Cordillera (southern Spain) reveals a complex trace fossil assemblage, including softground Ophiomorpha, firmground Arenicolites, Thalassinoides and Gastrochaenolites, and hardground Trypanites as well as possible Gastrochaenolites. The ecological replacement in the macrobenthic community is interpreted according to successive suites that are controlled mainly by substrate consistency. Variations in composition and abundance of trace fossils between suites can be ecologically and/or taphonomically determined.     

Taxonomy and palaeobiology of the Bathonian (Middle Jurassic) tulitid ammonite Morrisiceras

Taxonomic revision of a number of species belonging to the Middle Bathonian tulitid genus Morrisiceras (Morrisiceras Buckman - macroconchs and Holzbergia Torrens - microconchs) from the Polish Jura (south-central Poland) and England, shows that the genus is in fact represented by one, albeit morphologically very plastic (especially macroconchs), species Morrisiceras morrisi (Oppel). In the Polish Jura area, all of the previously described morphotypes of the macroconch, along with its microconch Holzbergia, are characterized by their identical stratigraphic ranges, both being confined to the Middle Bathonian Morrisi Zone. Much smaller microconchs (males) may have attained maturity earlier than their macroconchs (females). Morphologically very plastic macroconchs seem to have attained full maturity at various shell diameters. Such phenomenon is known in recent coleoids and similarly may be the result of changing environmental conditions. Palaeobiogeographically, the main area occupied by the species was confined to the epicratonic seas, which spread across what is now present-day central and North-West Europe, with some occurrences in western Asia (Turkmenistan/Uzbekistan) and sporadic occurrence in a deep-water facies of Apulia (Italy). Taphonomical observations suggest that Morrisiceras shells have not undergone significant post-mortem drifting or transport after deposition. The preservation of some of the Morrisiceras morphotypes, occurring as dorso-ventrally flattened specimens in the host clays, may indicate that they were quickly buried in life position after they have landed on the sea-floor.     

Ammonoid taphonomy, palaeoenvironments and sequence stratigraphy at the Bajocian/Bathonian boundary on the Bas Auran area (Subalpine Basin, south-eastern France)

Bas Auran, in south‐eastern France, is the candidate area for Global Boundary Stratotype Section and Point (GSSP) of the base of the Bathonian Stage (Middle Jurassic). In the Bas Auran area, upper Bajocian and lower Bathonian deposits are made up of limestone beds alternating with marls that correspond to the ‘Marno‐calcaires àCancellophycus’, below the ‘Terres Noires’ Formation. Taphonomic analyses of the successive ammonoid fossil assemblages provide new and complementary data for biostratigraphic completeness, palaeoenvironmental setting and sequence stratigraphy. Lithologic differentiation between limestone and marl intervals resulted from alternating episodes of carbonate input and starvation. Both lithologic phases may contain evidence for sedimentary and taphonomic reworking, associated with scours, that reflects low rates of sedimentation and stratigraphic condensation. Three successive types of elementary cycles resulted from increasing rates of stratigraphic condensation, sedimentary condensation and substrate stabilization during early Bathonian. The occurrence of reelaborated ammonoids (i.e. exhumed and displaced before their final burial) implies that tractive current flows or winnowing affected the burial of concretionary internal moulds. In the lower Bathonian strata, the dominance of homogeneous concretionary internal moulds of phragmocones, completely filled with sediment, is indicative of low rates of sedimentation and sediment accumulation, respectively associated with low degrees of stratigraphic and sedimentary condensation. However, at the Bajocian/Bathonian transition, hemipelagic, bed‐scale limestone–marl alternations show a maximum value of biostratigraphic completeness and there is no evidence for taphonomic condensation in the ammonoid fossil assemblages. Taphonomic analyses of the successive ammonoid fossil assemblages and taphofacies confirm the development of a deepening phase associated with sedimentary starvation, which characterizes the last episode within the deepening half‐cycle of third and second order cycles, in the Bas Auran area of French Subalpine Basin during early Bathonian.     

New fossil leaves and fruits of Lauraceae from the Middle Miocene of Fujian,southeastern China differentiated using a cluster analysis

The fossil record of Lauraceae can be traced back to the Early Cretaceous of eastern Asia based on fossil flowers. Here, we refer a number of new occurrences of leaf and fruit fossils of Lauraceae from the Middle Miocene of Zhangpu, Fujian, China, to seven species. These data provide evidence supporting the fact that a diverse subtropical, or tropical, Lauraceae-dominated evergreen forest surrounded this region 15 million years ago (Mya). The Lauraceae fossils presented in this paper provide evidence for the evolution of this group as well as new materials that enable the study of the Fujian Province Neogene flora. The fossils described in this paper fill in the gaps in studies about Lauraceae pollen in the Middle Miocene from Fotan, Fujian, China. In addition, these fossils also enrich the Middle Miocene fossil records of Lauraceae in eastern Asia, especially improving the study of the macrostructures and reproductive organs of fossil Lauraceae from southern China. The similarity between fossil and modern fruits shows that during the Middle Miocene the fruit morphological of Lauraceae have changed very little. We also identify families where the fossils we report belong to their closest relatives and can be used to reconstruct the paleoenvironment of Fujian in the Middle Miocene.     

南召发现的人类和哺乳类化石

本文记述的人类化石是一枚右下第二前臼齿,发现于河南省南召县鸡河右岸第二级阶地的堆积中。一起发现的哺乳类化石有剑齿虎、中国鬣狗、肿骨鹿、剑齿象、三门马和巨等二十一种。时代为中更新世。     

Mio-Pliocene mammals from the Middle Awash, Ethiopia

The Middle Awash paleontological study area, located in the Afar Rift of Ethiopia, has yielded fossils spanning the last six million years. The geology and geochronology of the Mio-Pliocene sites of the study area have been refined and a reliable chronostratigraphy has been established by ⁴⁰Ar/³⁹Ar radiometric dating. The latest Miocene Adu-Asa Formation is divided into four members distinguished from each other by silicic and basaltic tuff marker horizons, most of which are dated basaltic tuffs. Radiometric dating has constrained the age of the Adu-Asa Formation to between 5.2-5.8 Ma. These dates are also supported by paleomagnetic results and biochronology. More than 2,000 fossil specimens were collected from the Adu-Asa Formation between 1992 and 2000. These fossils document 64 mammalian species belonging to 32 genera, 23 families, and 8 orders. This assemblage includes a number of new taxa. Included in the assemblage are First and Last Appearance Datums (FADs and LADs) of some groups, including the earliest record of the hominid genus Ardipithecus. Most of the taxa indicate a predominance of mesic and wooded habitat during the deposition of the Adu-Asa Formation. In these deposits, colobines, viverrids, mustelids, bovines, boselaphines, and tragelaphines are abundant, whereas alcelaphines are absent. Quantitative analyses of biogeographic relationships of the Middle Awash Late Miocene (MALM) mammalian fauna indicate stronger relationships with other African sites than with faunas from Eurasian sites. The MALM deposits have generated a critical dataset for analytic work on past environments, biogeographic relationships, and African vertebrate evolution. Moreover, the geographic position of the Middle Awash, coupled with its precise calibration and chronological span, make it a key section for interpreting latest Miocene faunal interchanges between Africa and Eurasia.     

A new species of Eretmophyllum (Ginkgoales) from the Middle Jurassic of Turpan-Hami Basin,Xinjiang, China

A few specimens previously assigned to Eretmophyllum, based on the gross leaf morphology, lack cuticular structures. In this paper, we describe a new species of Eretmophyllum from the Middle Jurassic Xishanyao Formation in the Turpan-Hami Basin, Xinjiang Uygur Autonomous Region, northwestern China, based on fossil leaves preserved as compressions, and characterized by paddle shapes with conspicuous petioles, retuse apices, entire margins and two veins dichotomously branched from near the base. Leaf amphistomatic, the cuticles are composed of stomatal and non-stomatal bands. Based on a detailed comparison of the gross morphology and cuticular structures with previously reported fossils, Eretmophyllum hamiensis n. sp. is erected. The presence of Eretmophyllum indicates that Middle Jurassic climate in the Turpan-Hami Basin was likely warm and humid. On the basis of the geological history and geographical distributions of Eretmophyllum, we conclude that the genus probably originated in Europe and migrated from Siberia to northwestern China during the Middle Jurassic.     

The oldest Mesozoic nearshore Zoophycos: evidence from the German Triassic

The trace fossil Zoophycos has been described from the Middle Triassic carbonates of the German Basin for the first time. It occurs in a calcilutite bed at the top of a shallowing-upward cycle (parasequence) in the transgressive systems tract of the Middle to Upper Muschelkalk sequence of Thuringia (Germany). Based on sedimentological and palaeontological features, the studied interval is interpreted as deposited in a marine nearshore environment with proximal storm deposits (tempestites). Zoophycos occurs in a very simple planar form with lobate spreiten, which were most likely produced by a worm-like animal by strip mining. The upper tier of the ichnofabric consists of Zoophycos, whereas the lower tier is occupied by cylindrical trace fossils of unknown taxonomic affiliation and with decreasing size towards the bottom. Associated trace fossils such as Rhizocorallium, Balanoglossites and Trypanites indicate a partly firm to hard substrate. No mixed layer is developed at the top of the trace fossil bearing succession. The ichnofabric together with the sedimentological features (disseminated pyrite, blue-grey colour) and palaeontological circumstances (poor benthic fauna, meiofauna with a small body size) support an interpretation of a dysaerobic environment. In the view of evolutionary change, Palaeozoic Zoophycos occurs in both deep and shallow marine deposits, whereas Mesozoic and Cenozoic Zoophycos is only common in shelfal and deeper-marine deposits. The new finding from the shallow-marine Middle Triassic represents the first reliable occurrence of Zoophycos after the end-Permian mass extinction and shows close similarities to its Palaeozoic precursors. It demonstrates that the producer survived the end-Permian mass extinction, became re-established in the nearshore realm and progressively colonized deeper-marine environments during the Mesozoic and Cenozoic.     

Les Rhynchonelles du Bathonien du domaineprovencal: Liaison entre l'installation des peuplements et les modalités de la transgression bathonienne dans les Alpes-Maritimes

In the Maritime Alps, the Middle and Upper Bathoniancorresponds to a transgressive episode on the Provençal platform. The advancement of the marine invasion is very noticeable between Grasse and Antibes. The sediment shows the existence of a shallow marine environment in which benthic organisms were predominant.The deposits are at first varied: marly layers withbivalves (burrowers for the most part) and calcareous layers with monospecific populations of brachiopods (Burmirhynchia mediterranea nov. sp. in a calm environment, and B. turgidaBuckman in a more turbulent environment).The deposits then become uniform and show theexistence of very shallows environments: B. decorata kiliani nov. subsp. is the only representative of macrofauna in the micritic limestones that can be attributed to the Upper Bathonian.The Rhynchonellids, as on the other Bathonian carbonateplatforms of Western Europe, seem to be the only organisms likely to stay alive and proliferate in the specific environments in which entirely carbonate sediments are deposited in shallow water. Due to their relationships to those existing in other platforms, the species described in this article permit the clarification of biostratigraphic correlations.     

Deep-water trace fossils in the Ilfjellet rift basin (Middle Ordovician), central Norwegian Caledonides

The late Early to early Middle Ordovician Fjellvollen Formation, Central Norwegian Caledonides, is a part of the Ilfjellet Group volcano-sedimentary succession formed in a rift basin that opened along the Laurentian margin. Depositional facies and trace fossils indicate the Nereites ichnofacies, typically found in distal turbidites and deep marine deposits. The recovered trace fossils include ?Alcyonidiopsis, Chondrites, Dictyodora, Gordia, Helminthoidichnites, Macaronichnus, Monomorphichnus, Nereites, Oikobesalon, Palaeophycus, Protovirgularia and Treptichnus. No body-fossils have been reported from the Fjellvollen Formation, but the trace fossils indicate the presence of varied epi- and infaunas of arthropods, bivalves, gastropods and polychaets. The abundance of meandering and looping trace fossils is comparable to what is found in the inferrably time-equivalent Vuddudalen Group farther north, although lack of graphoglyptids like Megagrapton in the Fjellvollen Formation may indicate more proximal, unstable depositional conditions in fan-fringe and adjacent basin-plain settings.     

Endocranial traits of the Sima de los Huesos (Atapuerca,Spain) and Petralona (Chalkidiki,Greece) Middle Pleistocene ursids. Phylogenetic and biochronological implications

A complete cranium of Ursus deningeri from Petralona (Chalkidiki, Greece) covered by a thick carbonate crust has been virtually liberated through CT scan and 3D image reconstruction, and compared with a specimen from the Sima de los Huesos, Sierra de Atapuerca (Spain) Middle Pleistocene site. X-ray computed tomography allowed for the identification of previously unrecognized and phylogenetically relevant traits. Analysis of these traits and an additional series of classically defined traits demonstrate the near identity of these specimens, thereby, confirming an early stage of the speloid “(cave bear)” condition. The replicate luminescence ages obtained for the SH deposit provide a combined minimum age estimate of 427 ± 12 ka for the underlying fossils. Based on a series of primitive and derived morphological features of these two crania, a similar age is here proposed for the Petralona and SH U. deningeri.