Biostratigraphic Implications Research Articles

Insects in the Red Middle Permian of Southern France: first Protanisoptera (Odonatoptera) and new Caloneurodea (Panorthoptera), with biostratigraphical implications

The Permian odonatopteran Protanisoptera are discovered for the first time in the playa palaeoenvironments of Gonfaron and Lodève (Southern France). The new genus and species Bansheepteron gonfaronensis is erected and described on the basis of a distal half of a wing from the Guadalupian of Gonfaron. It is compared with all the previously described protanisopterans. Another specimen consisting of a basal half of a wing from the Guadalupian of Lodève, attributed to cf. Bansheepteron gonfaronensis, is also described. Furthermore, three new panorthopteran Caloneurodea are described from the Early to Middle Permian (Cisuralian and Guadalupian) of Southern France, viz. Gallogramma galadrieli gen. et sp. nov. from the le Luc Basin (Gonfaron, Var), and Paleuthygramma cf. acuta Carpenter, 1943 from the Lodève Basin (Hérault). These new fossils increase the palaeodiversity of the Caloneurodea, an interesting clade which now gathers six species in the red Permian of the Southern France, making it one of the most diverse clade in these palaeoenvironments after the Odonatoptera. The present discoveries better support a Guadalupian age for the Gonfaron Formation, even if a Late Cisuralian affinities remains possible.http://zoobank.org/urn:lsid:zoobank.org:pub:1955790C-EA66-4137-9300-3E1B76C1585Fhttp://zoobank.org/urn:lsid:zoobank.org:act:0E77F461-6096-4567-8477-AA3D0D1037D3http://zoobank.org/urn:lsid:zoobank.org:act:1D6DE829-BB0D-4EDA-9707-BFF442581601

The lower Darriwilian (Middle Ordovician) at the northern extreme of the Mendoza Precordillera, Argentina: stratigraphic and biostratigraphic implications

A tectonically affected Middle Ordovician succession crops out at the Los Guanacos quarry in the Sierra de Las Higueras, in the Precordillera of Mendoza, western Argentina. This is represented by the San Juan Formation which is transitionally covered by a mixed carbonate-shaly unit of dark colours, 1.5 metres thick (transfacies) which can be interpreted as the base of the Los Azules Formation. A 5-cm thick intra-bioclastic pack/grainstone bed interbedded in the lower part of this unit has been interpreted as a tempestite. It is characterized both by a millimetre-thick erosional boundary, just above the dark mudstone layer and strong mechanical distribution of bioclasts and intraclasts, suggesting sedimentary structures associated with a storm event of high energy possibly occurring in the middle part of the platform. Towards the bottom, a hummocky structure thin interval, under the dark mudstone, is interpreted as the record of another tempestite event. The mudstone represents the post-storm event reflecting the low energy of the marine water environment. The lenticular layer contains predominantly lingulid shells, trilobites and graptolites, all highly fragmented, which suggests they have been reworked and subsequently mixed and quickly redeposited during a storm event that caused the mortality of these faunas. The trilobites Mendolaspis salagastensis and indeterminate species of Matagnostidae, Illaenidae, Leiostegiidae, Encrinuridae, Telephinidae and Trinucleidae have been recorded for the first time at this locality. The conodont fauna allows the identification of the Yangtzeplacognathus crassus Zone, which indicates the lower Darriwilian (Middle Ordovician). Graptolites assignable to Levisograptus cf. Levisograptus austrodentatus and Levisograptus sp. are described for the first time in the studied area and biostratigraphic implications validate the early Darriwilian age for the bearing levels. Finally, based on the studied records, correlation with different regions at the Precordillera, northwestern Argentina and worldwide, as well as some paleoenvironmental considerations, are additionally discussed.

Size reduction and ornamental oscillation within a Barremian lineage of giant heteromorphic ammonites (Early Cretaceous, northwestern Tethyan margin)

Field sampling data in the Vocontian Basin (southeastern France) and Mallorca (Spain), at the transition between the lower and upper Barremian (upper Moutoniceras moutonianum Zone and lower Toxancyloceras vandenheckei Zone), provides new information about the early representatives of the ammonite family Ancyloceratidae. Several successive species of the genera Moutoniceras and Toxancyloceras are identified. A review of the history of the acquisition of the Astier collection by the Natural History Museum of London, which contains the holotype of the type-species T. vandenheckei, clarifies some misinterpretations which this species previously suffered. T. vandenheckei and M. eigenheeri are revised, and a new species is described: T. canuti sp. nov. With respect to an evolutionary perspective under biostratigraphic control, their phylogeny is considered (M. eigenheeri -> T. canuti sp. nov. -> T. vandenheckei). The hypothesis of the origin of the genus Toxancyloceras within the Moutoniceras is strengthened; this link is consistent both stratigraphically and morphologically. Moutoniceras appears to be the oldest known representative of the Ancyloceratidae, which is rooted in the early Barremian. The ontogenetic and evolutionary patterns of the phyletic lineage Moutoniceras/Toxancyloceras are twofold: the first concerns the ornamental changes (itself determined by three imbricated patterns) and the second involves the adult size. Both patterns determine two evolutionary phases through time: (1) the giant Moutoniceras and the progressive disappearance of the tubercles through heterochrony (paedomorphosis), and (2) the drastic size reduction and the reappearance of the tubercles from the “small” Moutoniceras to the Toxancyloceras (through heterochrony, with peramorphosis and a combination of pseudo-dwarfism, acceleration and graduaptation). The oscillation in disappearance and reappearance of the tubercles demonstrates a possible case of evolutionary reversibility where heterochrony helped by the progenesis impact, favours character repeatability in the evolutionary patterns. The results for the genera Moutoniceras and Toxancyloceras have significant biostratigraphic implications for the Tethyan Barremian. The status of T. vandenheckei as a zonal and subzonal index species (basal upper Barremian) is reinforced, and three new ammonite horizons are defined: the Moutoniceras eigenheeri, Toxancyloceras canuti and T. vandenheckei horizons. The stratigraphic distribution of all their index species is very restricted, indicating a well established evolutionary context.

New data on the Late Viséan–Late Serpukhovian foraminifers of northern Alborz, Iran (biostratigraphic implications)

The Upper Viséan–Upper Serpukhovian deposits of northern Alborz (Iran) consist of thin-bedded, fine sandstone and siltstone, marly and ooidal limestone and marly shale. Rich and diverse foraminiferal assemblages have been analyzed in two sections (Dozdehban and Naserabad). Five biozones and most foraminifers are first described from Upper Viséan–Upper Serpukhovian deposits of Iran. The Late Viséan of the area is subdivided into a Neoarchaediscus Zone and a Howchinia gibba–Archaediscus/Paraarchaediscus at angulatus-tenuis stage-Neoarchaediscus akchimensis Zone correlated to the Upper Mikhailovian–Venevian and Early to Late Brigantian substages of the Russian Platform and Western Europe. The Early Serpukhovian corresponds to the Biseriella parva–Climacammina Zone, and the Late Serpukhovian includes the Turrispiroides multivolutus–Brenckleina–Eostaffellina protvae zone that correlate to the Tarusian–Steshevian and Protvian substages of the Russian Platform, respectively. Furthermore, the upper beds in the Naserabad section contain the Plectostaffella–Globivalvulina kamensis? Zone, which is dated as Zapaltyubian?, lastest Serpukhovian.

Charophyte flora from the Brian Head Formation, southwestern Utah, and its biostratigraphic implications

The age of Cenozoic non-marine rocks exposed in southwestern Utah is controversial because they generally have discontinuous exposures, marked lateral facies changes, post-depositional diagenetic alteration, and scarce fossils. A well-preserved fossil charophyte assemblage is described here from the variegated unit of the Paleogene Brian Head Formation, along the western margin of the Sevier Plateau (Casto Canyon quadrangle). The charophyte assemblage is composed of three species previously documented in the European and Asiatic continents: Sphaerochara aff. major Riveline 1986, Hornichara aff. lagenalis (Straub 1952) Huang and Xu 1978, and Harrisichara tuberculata Grambast 1958. The biostratigraphic ranges of these three species suggest a relative age of late Eocene (Priabonian)-early Oligocene (Rupelian) for the base of Brian Head Formation. These results are consistent with recent isotopic studies undertaken in the underlying conglomerate at Boat Mesa and the overlying volcaniclastic unit of the Brian Head Formation which are both late Eocene in age. Hence, in agreement with this isotopic data, the charophyte flora from the Brian Head is late Eocene in age. Moreover, this study provides valuable data about the paleogeographic distribution of biostratigraphic-key species of the European Paleogene that have been reported, for the first time, in North America.

Placoderms from the Early Devonian “placoderm sandstone” of the Holy Cross Mountains, Poland with biostratigraphical and palaeobiogeographical implications

The Podlazie locality was examined during the fieldwork in 2011–2012 financed by the Ministry of Science and Higher Education (grant IP2010 041470 to PS).

Vertebrate fauna from the Late Triassic Tiki Formation of India: new finds and their biostratigraphic implications

Recent work on the Tiki Formation has resulted in the collection of new and varied vertebrate micro–and megafossils, including a new bonebed containing low diversity, mono–dominant, multitaxic vertebrate accumulation where the rhynchosaur, Hyperodapedon tikiensis constitute the dominant component. This bonebed has also yielded a large traversodontid cynodont Ruberodon roychowdhurii. In addition, there are several diagnostic postcrania such as vertebrae and incomplete limb bones belonging to a basal saurischian dinosaur. Systematic exploration and collection has yielded numerous isolated teeth and postcrania of small vertebrates such as different types of freshwater sharks, bony fishes, archosauriforms, lepidosauromorphs, cynodonts and other reptiles. Based on its fossil flora and fauna, the Tiki Formation is globally correlated with other coeval horizons such as the lower member of the Maleri Formation of the Pranhita–Godavari basin, the upper part of the Santa Maria Formation of Brazil, the Camp Springs and lower Tecovas formations of the Chinle Group, USA. A Carnian (Otischalkian to early Adamanian) age is proposed for the Tiki Formation.

A capitosauroid from the Lower Triassic of South America (Sanga do Cabral Supersequence: Paraná Basin), its phylogenetic relationships and biostratigraphic implications

Surviving through the end-Permian mass extinction, stereospondyls reemerged reaching a widespread distribution during the Early Triassic. A well representative lineage of this clade, Capitosauroidea, became worldwide abundant from Early to Late Triassic, in which their first undoubtful representatives were recovered from Lower Triassic deposits. Here, we describe a new capitosauroid, Tomeia witecki gen. et sp. nov., from the Sanga do Cabral Supersequence (Paraná Basin). Although relatively incomplete, the material presents a particular combination of early and late-diverging capitosauroid characters. Supporting Tomeia witecki as a new capitosauroid, our phylogenetic analysis placed the taxon as part of a clade that comprises only Early Triassic capitosauroids, specifically as the sister-taxon of the madagascarian Edingerella madagascariensis and close to Watsonisuchus spp., from Australia, South Africa and Madagascar. The status of Tomeia witecki as a new capitosauroid from western Gondwana supports a continuous record of the Stereospondyl lineage, since their first appearance during the Middle Permian in this supercontinent. Additionally, the temporal range of the Sanga do Cabral Supersequence during the Early Triassic was specifically reinforced as Olenekian, mainly based on the overall faunal content previously reported to this unit, associated with the known temporal distribution from those taxa phylogenetically closer to Tomeia witecki.http://zoobank.org/urn:lsid:zoobank.org:pub:7AA9F874-BED5-4A99-B098-B50656E706C1

A large moradisaurine tooth plate from the Lower Permian of Texas and its biostratigraphic implications

SUPPLEMENTAL DATASupplemental materials are available for this article for free at www.tandfonline.com/UJVPCitation for this article: Modesto, S. P., V. J. Flear, M. M. Dilney, and R. R. Reisz. 2016. A large moradisaurine tooth plate from the Lower Permian of Texas and its biostratigraphic implications. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1221832.

A new late Hemingfordian vertebrate fauna from Hawk Rim, Oregon, with implications for biostratigraphy and geochronology

ABSTRACTThe Hemingfordian North American Land Mammal Age is not well sampled, especially in the Pacific Northwest. Here we present both a description of a new fauna and two radiometric dates, 16.26 Ma and 16.44 Ma, constraining the Hawk Rim locality of central Oregon. Hawk Rim represents the first diverse late Hemingfordian fauna in the Northwest and is one of the stratigraphically lowest fossiliferous outcrops of the Mascall Formation. Much of Oregon was blanketed by Columbia River Flood Basalts during late Hemingfordian time, limiting not only outcrops but places for organisms to have survived. The site yields a taxonomically rich fauna sharing strong faunal similarity with the type locality of the Mascall but also containing taxa new to the formation and region. We describe occurrences of five genera of Artiodactyla, four genera of Perissodactyla, three genera of Rodentia, and six genera of Carnivora, with all but three new occurrences for the Hemingfordian of the Pacific Northwest. In particular, the carnivore fauna extends the geographic and temporal range of several carnivorans, and we describe a new hypercarnivorous mustelid, Watay tabutsigwii.http://zoobank.org/urn:lsid:zoobank.org:pub:B415069F-8BE6-4629-A872-5A640A644210SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVPCitation for this article: McLaughlin, W. N. F., S. S. B. Hopkins, and M. D. Schmitz. 2016. A new late Hemingfordian vertebrate fauna from Hawk Rim, Oregon, with implications for biostratigraphy and geochronology. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1201095.

Systematic palaeontology of the Perisphinctoidea in the Jurassic/Cretaceous boundary interval at Le Chouet (Drôme, France), and its implications for biostratigraphy

AbstractThis study describes ammonite taxa of the Perisphinctoidea in the Jurassic/Cretaceous boundary interval at Le Chouet (Drôme, France). Emphasis is placed on new and poorly known Himalayitidae, Neocomitidae and Olcostephanidae from the lower part of the Jacobi Zoneauctorum. Significant results relate the introduction ofLopezicerasgen. nov., grouping himalayitid-like forms with two rows of tubercles, andPraedalmasicerasgen. nov., grouping the early BerriasianDalmasicerastaxa. Study of the ontogenetic sequences of both genera show that they were derived from late Tithonian Himalayitidae. This supports the distinction between the subfamilies Himalayitinae and Dalmasiceratidae subfam. nov. Content, variation, dimorphism and vertical range of the NeocomitidaeBerriasella,Pseudoneocomites,ElenaellaandDelphinellaare discussed. A conservative use of the OlcostephanidaePronicerasis followed herein.

WITHDRAWN: Comment on "Terreneuvian small shelly faunas of east Yunnan (South China) and their biostratigraphic implications" by B. Yang et al. [Palaeogeography, Palaeoclimatology, Palaeoecology 398 (2014) 28-58

The recent article by Yang et al. (2014 provides a very useful summary of the litho- and biostratigraphy of the sub-trilobitic lower Cambrian on the tropical shelf of South China. Our concern with this article is that it did not draw on or utilize existing reports that followed IUGS protocols in the proposal of a GSSP horizon and locality for informal Stage 2 of the lower Cambrian. Indeed, a proposal of an integrated bio- and chemostratigraphic signature (i.e., the peak of the L4 carbon isotope excursion within the Watsonella crosbyi Assemblage Zone in South China) for the base of Stage 10 and the location of a Stage 2 GSSP 9 m below the top of the Dahai Member at the Laolin roadcut offers the potential for correlation of a Stage 2 base across southern China and globally (i.e., into Siberla and Avalonia).

Macrofauna and paleobiogeography of the Callovian Tuwaiq Mountain Formation in central Saudi Arabia

Forty-six Callovian macrofaunal species including 13 brachiopods, 19 bivalves, and 14 gastropods were collected from three surface sections—Shaib Al Hisyan, Khashm Al Giddiyah, and Dirab—in the Tuwaiq Mountain Formation around Riyadh City in central Saudi Arabia. The fauna is discussed systematically and with respect to biostratigraphic implications and its paleobiogeographic distribution. Four macrobiozones with two barren intervals are identified. These zones are from base upward: Pholadomya (Bucardiomya) lirata, Barren interval (1), Sphringanaria capax, Pholadomya inornata, and Coral Zone of Middle Callovian age and Barren interval (2) of Middle to Late Callovian age. The paleobiogeographic distribution of the fauna confirmed the endemism along the southern Tethyan margin of the Ethiopian Province.

Conchostracans in continental deposits of the Zechstein–Buntsandstein transition in central Germany: Taxonomy and biostratigraphic implications for the position of the Permian–Triassic boundary within the Zechstein Group

The end-Permian mass extinction marks the largest biotic crisis in the geologic record. The stratigraphic position of this boundary in continental deposits is still under discussion. In the present study, conchostracans from the Zechstein–Buntsandstein (Late Permian to Early Triassic) transition in central Germany have been taxonomically reinvestigated in order to better understand their utility for fine-scale biostratigraphy in continental Permian–Triassic boundary sections. The studied material was obtained from both collections and recent sampling activities in classical key sections and new outcrops of the Zechstein and Buntsandstein Groups. The sedimentary environments of the conchostracan occurrences are interpreted as lacustrine to fluvial facies depending on the paleogeographic position within the basin of the respective sections. The conchostracan fauna in the Zechstein–Buntsandstein transition consists of Euestheria gutta, Palaeolimnadiopsis vilujensis, Cornia germari, Estheriella marginostriata, Estheriella costata, Estheriella nodosocostata, Magniestheria mangaliensis, and Euestheria nordvikensis. Based on comparison with the Early Triassic conchostracan record in the Moscow syncline, the Palaeolimnadiopsis vilujensis–Euestheria gutta association in the upper part of the Fulda Formation indicates both its Early Triassic age and a position of the continental Permian–Triassic boundary within the Zechstein Group.

Palynology of the upper Chinle Formation in northern New Mexico, U.S.A.: Implications for biostratigraphy and terrestrial ecosystem change during the Late Triassic (Norian–Rhaetian)

A new densely sampled palynological record from the vertebrate-bearing upper Chinle Formation at Ghost Ranch in the Chama Basin of northwestern New Mexico provides insights into the biostratigraphy and terrestrial ecosystem changes during the Late Triassic of northwestern Pangaea. Spore–pollen assemblages from the Poleo Sandstone, Petrified Forest, and ‘siltstone’ members are dominated by pollen of corystospermous seed ferns (Alisporites) and voltziacean conifers (Enzonalasporites, Patinasporites). Other abundant taxa include Klausipollenites gouldii and the enigmatic fused tetrad Froelichsporites traversei, whereas spores of ferns and fern allies are generally rare. The assemblages are correlated with Zone III Chinle palynofloras of previous authors. The lower assemblages contain rare occurrences of typical Zone II taxa, namely Cycadopites stonei, Equisetosporites chinleanus and Lagenella martini, that may either be reworked or represent relictual floral elements. Marked step-wise losses of species richness, along with only minor appearances of new taxa, led to a total 50% drop in range-through diversity during the late Norian of the Chama Basin. Correlations with other Chinle records in the western U.S. reveal differences in the stratigraphic ranges of some spore–pollen taxa, likely attributable to local/regional differences in environmental conditions, such as groundwater availability, precipitation, nutrients, and temperature, rather than stratigraphic miscorrelation. This is interpreted as a consequence of environmental stress resulting from increased aridity coincident with the northward movement of Pangaea. Similarly, major differences between the western and eastern U.S. and northwestern Europe can be attributed to floral provincialism governed by climatic zones during the Late Triassic.

Palaeoenvironmental and biostratigraphic implications of microbial mat-related structures: Examples from the modern Gulf of Cambay and the Precambrian Vindhyan Basin, India

A stretch of the modern hypersaline coastal plain of the Gulf of Cambay was chosen to examine the distribution of the microbial mat-related structures (MRS) on siliciclastic sediments in the intertidal and supratidal zones. The abundance of MRS increases from the lower intertidal zone to the upper supratidal zone while the type of MRS records a systematic change. While the lower intertidal zone exhibits wrinkle structures, sieve-like surfaces and patchy ripples in places, the upper intertidal zone exhibits diverse MRS related to reduced current activity on the mat layer and intermittent exposure. MRS in the upper intertidal zone include wrinkle structures, sieve-like surfaces, gas domes, reticulated surfaces, multi-directional ripples, patchy ripples, rolled-up mat fragments, setulfs and occasional petee ridges and cracked mat surfaces. The lower supratidal zone is characterized by increased occurrence of petee ridges, gas domes and cracked mat surfaces compared to the upper intertidal zone. The upper supratidal zone is distinguished by the presence of abundant cracked mat surfaces, petee ridges, gas domes and wrinkle structures. The presence of cm-scale, disc-shaped microbial colonies (DMC) with a variety of internal structures is a unique feature of the Gulf of Cambay study area. While wrinkle structures occur in all the coastal zones, setulfs occur close to the boundary between the upper intertidal and lower supratidal zones. An attempt has been made to compare the distribution of MRS in this modern environment with those in the ~1.6Ga Chorhat Sandstone of the Vindhyan Supergroup for high-resolution palaeoenvironmental interpretation. The upper part of the intertidal segment of the Chorhat Sandstone is distinguished from its lower part by the presence of abundant cracked mat surfaces, petee ridges and gas domes in the former, while wrinkle structures, Kinneyia, rolled-up mat fragments, patchy ripples and multi-directional ripples are equally abundant in both parts. The lower part of the intertidal segment of the Chorhat Sandstone is thus analogous to the upper intertidal zone of the modern Gulf of Cambay environment, while the upper part of the Chorhat intertidal segment reflects prolonged exposure close to the high tide line. The bottom-most part of the intertidal segment of the Chorhat Sandstone with fewer MRS corresponds to the lower intertidal zone at Cambay. Inferred disc-shaped microbial fossils within Vindhyan sandstones are analogous to the DMC found in the modern environment and these features do not have any biostratigraphic implication.

Miocene/Pliocene mammal faunas of southern Balkans: implications for biostratigraphy and palaeoecology

Even though there are numerous late Miocene mammal localities in the southern Balkans, those of late Turolian and early Ruscinian age are uncommon. Using the available data, mainly from Greece and Bulgaria, we compiled information about the faunal and palaeoenvironmental changes at the Miocene/Pliocene boundary. The analysis of the faunal elements indicates that several Miocene taxa disappeared, whereas new taxa appeared. The faunal composition of the mammal zones suggests a decrease of the bovids and giraffids and an increase of cervids and suids from MN 12 to MN 14. The available faunal assemblages from zones MN 12–MN 14 are compared with a set of modern and fossil assemblages from known environments to determine their palaeoenvironment. The results indicate an increase of the closed character of the environment from MN 12 to MN 14, suggesting a gradual increase of the humidity and the development of more forestial conditions. The rodent faunas from northern Greece ranging from MN 13 to MN 14 show a characteristic aridification of the biotopes and the introduction of African elements in the last part of the MN 13 (during the Messinian Salinity Crisis), with a subsequent return of humid-and/or-forested biotopes towards the MN 13/14 boundary. The faunal and sedimentological data for the Greek localities correlated with the Turolian/Ruscinian boundary suggests a general open landscape with several water spots of variable sizes surrounded by dense forests.

Palaeoecological and biostratigraphical implications of the microvertebrates of Qesem Cave in Israel

Microvertebrates are generally well suited for drawing inferences on past environmental conditions because they are closely bound to the areas in which they lived. In this paper, we discuss palaeoecological implications of two microvertebrate concentrations in the Middle Pleistocene site Qesem Cave in Israel. The ecological preferences of the nearest living relatives of the microvertebrate taxa recorded in Concentration 1 (squares L–N/13–15) and 2 (squares G-H/16–17) at Qesem Cave allow us to infer a mosaic of open palaeoenvironment with sparse vegetation, shrubland, Mediterranean Forest, rocky areas and riverbanks. Additionally, we infer palaeoclimate from the bioclimatic distribution of extant species using the Coexistence Approach. To our knowledge, this is the first time the approach has been applied to microfaunal assemblages. These data suggest cooler and slightly drier winters and somewhat lower seasonality than at present around Qesem Cave; the differences are more pronounced for the time covered by Concentration 2 than Concentration 1.Among microvertebrates, micromammals are most suitable for biostratigraphic purposes. With the exception of Rattus cf. haasi and the Myomimus judaicus/setzeri group, the small mammal fauna of Qesem Cave comprises only taxa that live today in the Levant. R. haasi and M. judaicus have been found in Israel in the Early and Middle Pleistocene, and their latest known record was from the Acheulian site of Oumm Qatafa. Their presence in Qesem Cave extends the previously known stratigraphic range of these species. The absence of R. haasi in Mousterian sites is thus consistent with the pre-Mousterian age of Qesem Cave. Morphometric data on molars of Guenther's Vole show that the lineage segment preserved in Concentration 2 is more primitive than in Concentration 1, indicating that the former concentration is older. The evolutionary level of the sample from Qesem Concentration 1 is similar to Tabun D (boundary of Acheulo-Yabrudian Cultural Complex and Mousterian), and that from Qesem Concentration 2 similar to Tabun Eb (Acheulo-Yabrudian).

Organic-walled microfossils from the Tonian Gouhou Formation, Huaibei region, North China Craton, and their biostratigraphic implications

The Meso-(?) and Neoproterozoic Huaibei Group in the Huaibei region, North China Craton (NCC), is emerging as a target for geobiological and tectonic studies due to its thick unmetamorphosed sediments with well-preserved organic-walled fossils. However, the lack of accurate age constraints for this sedimentary sequence dramatically hampers our ability to take full advantage of the rich geological and paleontological history recorded in the Huaibei Group. Particularly, the depositional age of the uppermost unit of the Huaibei Group, the Gouhou Formation, is a controversial issue. Although it is widely accepted that there is an unconformity between the Gouhou Formation and the overlying early Cambrian Houjiashan Formation, the magnitude of this unconformity and hence the scale of the underlying tectonic event are unconstrained due to the uncertainty of the sedimentary age for the Gouhou Formation which has been variously interpreted as Cambrian, Cryogenian–Ediacaran (∼720Ma to ∼541Ma), and Tonian (1000Ma to ∼720Ma). To improve our knowledge about this sedimentary gap, we carried out a biostratigraphic study of the Gouhou Formation. Our investigation using a low manipulation maceration technique revealed a diverse organic-walled microfossil assemblage. A total of 22 taxa have been revealed, including a new species—Dictyosphaera tacita n. sp. Importantly, the co-occurrence of Trachyhystrichosphaera, Valeria, and Dictyosphaera in the Gouhou Formation suggests a likely Tonian age. The biostratigraphic data indicate an infra-Cambrian depositional gap of >200myr between the Tonian Gouhou Formation and Cambrian Houjiashan Formation, perhaps driven by a major tectonostratigraphic event.

Middle and Late Maastrichtian (Latest Cretaceous) Ammonoids from the Akkeshi Bay Area, Eastern Hokkaido, Northern Japan and Their Biostratigraphic Implications

Nine ammonoid species are reported from the Maastrichtian Senpohshi Formation exposed along the western coast of Akkeshi Bay, eastern Hokkaido, and their respective chronologic assignments are discussed on the basis of a previous magnetostratigraphic study. Pachydiscus flexuosus occurs in the lower and middle parts of the formation (= polarity chron C31n, i.e., middle to upper middle Maastrichtian). Gaudryceras makarovense, Anagaudryceras matsumotoi and Diplomoceras cf. notabile and P. flexuosus as well occur in the lower part (middle middle Maastrichtian). The uppermost part of the formation (= probably the lower part of polarity chron C30n, i.e., lower upper Maastrichtian) is fossiliferous and yields a diverse ammonoid assemblage including Neophylloceras sp., Pseudophyllites sp., Zelandites varuna, A. matsumotoi, Gaudryceras cf. seymouriense, Gaudryceras sp., and D. cf. notabile. Integration of bio- and magnetostratigraphy in the Senpohshi Formation makes it possible to determine precise and detailed chronologic assignment of strata containing similar faunas in the Northwest Pacific realm.