Early Pleistocene Deposits Research Articles

The first confirmation of North American extinct shrub-ox (Euceratherium, Artiodactyla, Mammalia) in the Early Pleistocene of northern China

Euceratherium is a genus generally considered to represent an Ovibovine member of the Caprini, and up to date considered to occur only in North America. Here, we describe two species of Euceratherium discovered from the Early Pleistocene deposits in northern China, E. collinum and Euceratherium sp., the first confirmed record of Euceratherium in Eurasia and outside North America. The earlier age of Chinese Euceratherium than that of its North American counterpart indicates that Euceratherium might originate from East Asia and spread into North America later. The phylogenetic analysis based on the North American and our Euceratherium collinum materials indicates its closer relationship to Ovibos moschatus than the other bovids. Ecomorphological analysis based on the teeth and metapodials of Euceratherium sp. from Xinyaozi suggests that the Chinese species has the same paleodiet and paleohabitat preferences as those of its North American counterpart. By broadening our study from Euceratherium to its upper taxonomic group, the Quaternary Ovibovine, we found that the latter probably originated from a Kabulicornis-like form and could be divided into two groups in the Late Pliocene, “alticornis” and “depressicornis”. These two groups evolved in Eurasia in the Early Pleistocene. They might disperse from Eurasia to North America twice, in the late Early Pleistocene and the late Middle Pleistocene, respectively.

The Hasli Formation of the Irchel Plateau – A key record for older Early Pleistocene interglacial sediments in northern Switzerland

In the Alpine region of Central Europe, terrestrial Early Pleistocene deposits with preserved faunal and botanical remains are rare. The predominantly gravelly Höhere Deckenschotter (HDS) deposits of northern Switzerland and adjoining south-western Germany are considered the oldest Quaternary sediments in the northern Alpine Foreland, linked with the first extensive Quaternary Alpine glaciations.This multidisciplinary study investigates the Hasli Formation (HF), a unique silty unit with well-preserved biological remains within an HDS sequence at the Irchel Plateau north of Zürich, providing new climatic and environmental data for these exceptional deposits, as well as crucial information about their age. Systematic mapping of the HF, in addition to the underlying and covering gravel units, has been coupled with sedimentary logging and biostratigraphic analysis at several sites. The HF is present over an area c.4 by up to 1.4 km, and where studied is 1.6–6.2 m thick. The sediments and biological material are indicative of overbank deposits accumulating within the damp floodplain of a large meandering river.The recovered small mammal remains are from eight arvicolid species or genera, including Mimomys pliocaenicus, M. reidi/tigliensis and Clethrionomys cf. kretzoii, which became extinct c.1.8 Ma, and Pliomys episcopalis/simplicior, which first appeared c.2 Ma ago. The over 75k identified molluscs, include c.72k coming from 89 terrestrial species and over 3k from 28 aquatic taxa. The molluscan faunas from all locations where the HF has been studied share important biostratigraphic marker species, and indicate analogous climatic and environmental conditions. The marker species include several that became extinct during the Early Pleistocene, of which Clausilia stranzendorfensis and Cochlostoma salomoni, present throughout the HF, are the most important as they disappeared c.1.8 Ma. Many marker species have modern or palaeo-distributions that lie far to the west, south and east of the Swiss Plateau, showing that the climate was much warmer than today, typical for the Tiglian warm stage. The alluvial floodplain was covered by rather dense, mature woodland.Amino acid (AA) analysis shows that molluscan remains from the HF are among the oldest of the Quaternary shell material studied from across the Swiss Plateau. Palaeomagnetic data shows a change from reversed to normal polarity within the upper part of the HF. When combined, the small mammal and molluscan remains, palaeomagnetic measurements, AA geochronology and sedimentary data, suggest an age of 2.1–1.8 Ma for the HF. Recently produced cosmogenic dates bracket the age of the HDS gravels beneath the HF to depositional periods between 2.6 and 0.9 Ma, with the youngest ages being in disagreement with our findings. The abundance and diversity of the molluscs from the Irchel Plateau, with several rare extinct species, together with a notable small mammal assemblage, make this a key palaeontological site and an important reference point for European Quaternary biostratigraphy.

Core-Shaped Tools from the Early Pleistocene Deposits at Bairaki, Moldova

This a rticle deals with a series of core-shaped tools from Early Pleistocene deposits (layers 5 and 6) of the stratifi ed site of Bairaki, located on high above-fl oodplain terrace VII of the Dniester, in the outskirts of Dubăsari, Moldova. The site was discovered in 2010 by the joint Russian-Moldovan archaeological expedition and excavated in 2011– 2014. The interdisciplinary studies revealed six layers with Early Paleolithic artifacts. Two lowest layers (5 and 6) are associated with the channel alluvium of terrace VII. The paleomagnetic studies have shown that these deposits correspond to the Jaramillo episode of the Matuyama epoch. The lithic industry of layers 5 and 6 are comparable to the Late Oldowan. Most artifacts are made of poor quality fl int; there are also pebble tools made of non-silicic rocks. Most lithics are small. A distinct series of core-shaped end-scrapers and side-scrapers made on residual cores (9 spec.), fragments (1 spec.), and fl akes (5 spec.) is identifi ed. All these tools are robust and had been processed in a similar way. They are made of pebbles no larger than 6 сm. The steep working edges of all implements in this series are heavily retouched. Similar items have been recorded from the Early Paleolithic materials of the region. Such tools were widespread in the Early Paleolithic of Africa and Eurasia. The earliest pieces were found in the Bed I assemblage of the Olduvai Gorge.

CO2-Degassing Carbonate Conduits in Early Pleistocene Marine Clayey Deposits in Southwestern Umbria (Central Italy)

Early Pleistocene marine deposits in southwestern Umbria (Orvieto–Allerona area, Italy) recently revealed the presence of more than forty carbonate conduits distributed over 2 km along the Paglia riverbed. In order to investigate their origins, analyses of their mineralogy, δ18O and δ13C stable isotopes, and organic geochemistry were conducted. All the carbonate conduits are made of euhedral microcrystals of dolomite with subordinate quartz, plagioclases, and micas. The stable carbon and oxygen isotope values of the bulk concretionary carbonates range from −0.57 to +4.79‰ (δ13C) and from +1.58 to +4.07‰ (δ18O), respectively. The lack of organic geochemical biomarkers of anaerobic methane oxidation (AOM) and the very low values of extractable organic matter suggest a non-biological origin for the dolomite precipitation. The latter is probably related to the rise of volcanic carbon dioxide due to the incipient Vulsini magmatism recorded in Early Pleistocene marine deposits all around the study site. The spatial distribution of the structures indicates that the upward migration of the CO2 was controlled by the fault system, while the vertical development of the conduits suggests that carbon dioxide degassing occurred, with multiple events. Carbon dioxide was probably stored in pockets within the clayey sediments until the pressure exceeded the eruptive threshold. These structures represent the first documentation of a volcanic carbon dioxide marine seepage event in the Umbria region.

Biostratigraphy and palaeoenvironments of early Pleistocene deposits in the southern part of the Gulf of Tonkin, Vietnam

This study investigates the biostratigraphy and palaeoenvironments of the early Pleistocene deposits in the southern part of the Gulf of Tonkin, Vietnam. Biostratigraphic data, sediment cores, well-logs, and seismic data were used to analyse and construct the chronostratigraphy and paleo-depositional environments of the study area. The microfossil assemblages were recognized using new datasets from five exploration wells, including the biomarker calcareous nannofossils (Gephyrocapsa oceanica, Pseudoemiliania lacunosa, Helicosphaera sellii,Calcidiscus macintyrei, and Discoaster brouweri); the foraminifera (Globigerinoides obliquus, Globorotalia truncatulinoides, and Globorotalia tosaensis); and the palynomorph biomarkers (Phyllocladus spp. and Podocarpus imbricatus). By integrating these assemblages with the well-logs and seismic data, a detail chronostratigraphic framework for the early Pleistocene deposits of the study area was established. The early Pleistocene deposits can be subdivided into four calcareous nannofossil biozones, including CNPL7, CNPL8, CNPL9, and lower CNPL10, with the top of boundaries dated at 1.60 Ma, 1.24 Ma, 1.06 Ma, and 0.739 Ma, respectively. The results also provide useful information about depositional environments that are interpreted as shallow marine environment in the lower part of early Pleistocene, which has been identified as the calcareous nannofossil zones (CNPL7 and CNPL8). These zones are characterized by a change from a delta front to prodelta, with prograding seismic reflectors. The upper part of the early Pleistocene includes the calcareous nannofossil zones (CNPL9 and lower CNPL10) that correspond to a widespread area of middle-outer neritic environment with parallel to subparallel seismic reflections. In addition, the Pliocene/Pleistocene boundary in the southern part of the Gulf of Tonkin is dated at 1.93 Ma. This boundary is also equivalent to the base of the Ledong Formation in the Yinggehai Basin and the Qiongdongnan Basin, to the top of Wanshan Formation in the Pearl River Mouth Basin, in offshore China.

Integrated Stratigraphy of the Marine Early Pleistocene in Umbria

Through time, the wide area between southeastern Tuscany, northeastern Latium, and western Umbria has been revealed as a crucial area for understanding the evolution of Neogene basins in northern Apennine. In this study, the results of twenty years of research on the marine early Pleistocene deposits are summarized, and the biological and physical events are presented and discussed in order to propose an integrated stratigraphic scheme. The proposed reconstruction is also included in a wider context, taking into account both the local and regional geological evolution.

Pleistocene organic matter modified by the Hiawatha impact, northwest Greenland

AbstractThe 31-km-wide Hiawatha impact crater was recently discovered under the ice sheet in northwest Greenland, but its age remains uncertain. Here we investigate solid organic matter found at the tip of the Hiawatha Glacier to determine its thermal degradation, provenance, and age, and hence a maximum age of the impact. Impactite grains of microbrecchia and shock-melted glass in glaciofluvial sand contain abundant dispersed carbon, and gravel-sized charcoal particles are common on the outwash plain in front of the crater. The organic matter is depleted in the thermally sensitive, labile bio-macromolecule proto-hydrocarbons. Pebble-sized lumps of lignite collected close to the sand sample consist largely of fragments of conifers such as Pinus or Picea, with greatly expanded cork cells and desiccation cracks which suggest rapid, heat-induced expansion and contraction. Pinus and Picea are today extinct from North Greenland but are known from late Pliocene deposits in the Canadian Arctic Archipelago and early Pleistocene deposits at Kap København in eastern North Greenland. The thermally degraded organic material yields a maximum age for the impact, providing the first firm evidence that the Hiawatha crater is the youngest known large impact structure on Earth.

Environmental fluctuation impacted the evolution of Early Pleistocene non-human primates: Biomarker and geochemical evidence from Mohui Cave (Bubing, Guangxi, southern China)

Quaternary climate variability, profoundly impacting the evolution and distribution of plants and animals across the globe, has been reconstructed by many sediment archives. Here, we track past changes of temperature, rainfall and plant type by using the n-alkane and glycerol dialkyl glycerol tetraethers (GDGTs), as well as weathering and pedogenesis by mineralogical and geochemical proxies from a 250 cm deep soil sediment profile from the Early Pleistocene deposits in Mohui Cave, southern China. Indices for weathering intensity such as mineral composition (quartz, feldspar and calcite), major element proxies (Ti/Na, Al/Na, Al/Mg, Ti/Mg, CIW, PIA, CPA, CIA), trace element proxies (Ba/Sr and Rb/Sr), and biomarker proxies (OEP, LSR and CPI) show similar secular trends, revealing a three-stage historical accumulation. The high long-chain n-alkane ratios (C31/C29 and (C31+C33)/(C27+C29)) indicate that the vegetation in the region had increases in percentage of woody plants and decreases in herbs during periods of relatively lower temperature and less precipitation, which evidenced from GDGTs, consistent with a weak weathering process influenced by summer monsoon strength. Further, we compared the distribution of these plant types with the taxonomic variation in the vertebrate paleontological fossils excavated from the same profile in Mohui Cave. The distribution of Lufengpithecus appears in only one interval but Gigantopithecus blacki appears throughout the profile, despite an environment that experienced transitional stages from grassland to woodland in relatively cooler and drier conditions. We infer that in face of these climatic changes Lufengpithecus may have preferred to emigrate from the region, while Gigantopithecus blacki may have stayed given that it was limited to staying in its core area.

Geochemistry of lavas from Aegina and Poros (Aegean Arc, Greece): Distinguishing upper crustal contamination and source contamination in the Saronic Gulf area

Pliocene (Phase 1) deposits from the volcanic centres of Aegina and Poros (western Aegean Arc) consist of andesitic-dacitic lava flows and domes with mafic enclaves, whereas basaltic-andesitic and rhyolitic lava flows were emplaced during the early Pleistocene Phase 2 and its precursor activity. Fifty-nine new whole rock analyses of lavas and enclaves show geochemical characteristics in keeping with their continental arc setting, with a significant spread in Sr-Nd-Hf-Pb isotope compositions and a strong crustal imprint (e.g. 87Sr/86Sr 0.7041–0.7076). Unlike other Aegean volcanic centres, the Phase 1 deposits show high Ba concentrations and high Ba/Th ratios. These are unlikely to be a signature of fluid-mediated metasomatism of the mantle wedge; subduction of barite-enriched sediments appears a more plausible option. The amount of sediment added to the mantle wedge is ca. 4%. High 208Pb/204Pb relative to 206Pb/204Pb, especially for the Poros lavas, points towards contamination with continental crust similar to the basement of Ios. First-order modelling shows that up to 35% crustal contamination took place. Additionally, crystal fractionation, magma mixing and crystal accumulation shaped the whole rock geochemistry. Similar to the neighbouring island of Methana, the widest isotopic variation is seen in the early Pleistocene deposits, reflecting remobilisation of magma from the previous volcanic episode by isotopically more primitive mafic magmas after a period of volcanic quiescence. The isotopic contrast between the volcanic centres of the Saronic Gulf and those of Santorini and Kos-Nisyros further west is likely related to the geometry and physical characteristics of the subducting slab and mantle wedge, rather than the actual amount of sediments subducted or their composition.

The New Pleistocene Ulan-Zhalga Key Section in Western Transbaikalia

This work presents the first results of a multidisciplinary study of the new Pleistocene Ulan-Zhalga section (51°29′40.75″ N, 107°20′18.11″ E), discovered in Western Transbaikalia in 2017. Based on the paleontological, paleomagnetic, and lithological data, the Early, Middle, and Late Pleistocene deposits were distinguished in the section. The analysis of the species composition of small mammals allowed us to trace the paleoenvironmental and climatic changes in the region during the Quaternary. The unique succession of 19 faunal horizons and 11 horizons of buried soils in the section and a high degree of correlation of the paleomagnetic and paleontological data allow us to state that the studied Ulan-Zhalga section can serve as an important object for paleogeographical reconstruction and biostratigraphy. In addition, the new data obtained allow us to refer this section as one of the Upper Cenozoic key sections of the southern Eastern Siberia.

Several Lower Palaeolithic Sites along the Rhine Rift Valley, Dated from 1.3 to 0.6 Million Years

The important discoveries of Lower Palaeolithic artefacts in stratigraphical context within Lower and early Middle Pleistocene deposits in the western continental part of Europe along the rift systeme of the Rhine Valley are pointing at the possible continuous presence of hominins since the Lower Pleistocene. This paper reports on lithic industry from its early appearance at around 1.3 million years (Ma) at the site of Münster-Sarmsheim to the latest pre-Elsterian period at around 0.6 Ma at Mauer, Mosbach, and Miesenheim.

Biostratigraphy of the Early Pleistocene (Palaeopleistocene) deposits of the Southern Fore-Urals, Russia

A summary of published and unpublished data on the stratigraphy of the Early Pleistocene (Palaeopleistocene) of the Southern Urals region is presented in this paper. The summary follows previous reviews about the characteristics of the Pleistocene deposits of the easternmost part of Europe. The improvement and unification of the Regional Quaternary stratigraphical scheme was the main aim of these investigations. Deposits of different origin, which constitute the regional stratigraphical units (Zilim-Vasilyevo, Akkulaevo and Voevodskoe), are characterized. Malacological data form the base for the biostratigraphical subdivision. At the beginning of the Early Pleistocene, an ingression of the Akchagyl Sea (modern Caspian Sea area) began in the Zilim-Vasilyevo time, which developed as much as possible during Akkulaevo time, and then shortly re-emerged after regression into the territory of the Southern Fore-Urals during Voevodskoe time. During the Early Pleistocene (Palaeopleistocene), the Southern Fore-Urals region was characterized by continental climate conditions, which were influences by the wideapreaded brackish-water gulf of the Akchagyl Sea. Fossil molluscs, ostracods, mammals and pollen are used for the reconstruction of the palaeoenvironmental conditions and the biostratigraphical position of the main localities. The units have been correlated with the Gelasian stage of the Western European stratigraphical timescale.

An environmental scenario for the earliest hominins in the Iberian Peninsula: Early Pleistocene palaeovegetation and palaeoclimate

The Early Pleistocene deposits of the Iberian Peninsula provided some of the oldest hominin fossil sites of Western Europe. Evidence also shows that early Homo thrived in the Mediterranean peninsulas during the Early Pleistocene ‘interglacial’ phases. To assess the role of climatic conditions on early human environments, the present work features a quantitative palaeoclimatic analysis for a number of Early Pleistocene macroflora and pollen assemblages located at different geographical locations where hominin activity has been recorded. The results picture a cyclic climate with a possible latitudinal aridity gradient. Warm and humid (‘interglacial’) phases would have been wetter and slightly warmer than the modern climate. During cooler and drier (‘glacial’) phases, temperature and precipitation were comparatively milder and more similar to modern ones. The favourable conditions during the humid phases may have allowed for the earliest hominin communities arriving in Europe to rapidly thrive during ‘interglacial’ periods. The present climatic quantification suggests that hominins in Iberia may have survived these mild ‘glacial’ Early Pleistocene stages.

First occurrence of <i>Duboisia</i> (Bovidae, Artiodactyla, Mammalia) from Thailand

Abstract. The first fossil record of Duboisia (Boselaphini, Bovidae) from Thailand confirms that this genus is no longer endemic to Java, Indonesia. The new fossil material is a calvarium with horn cores (older than the Middle Pleistocene) collected from a sandpit at Tha Chang, Nakhon Ratchasima Province, north-eastern Thailand. The present specimen is provisionally allocated to a species of Duboisia aff. D. santeng, which has weaker precornual ridges and anterior keels on the horn cores than D. santeng from Early and Middle Pleistocene deposits of Java, but these species share basic characteristics of horn cores as follows: the lower half inclined backwards; the upper half curved upwards; cross section rounded triangular, antero-posteriorly compressed, and with medial and lateral keels. Morphological similarities between D. aff. santeng and D. santeng support a strong faunal interchange between continental South East Asia and Java before the Middle Pleistocene, and suggest that the genus Duboisia diverged from the other genera of Boselaphini in the “Siva-Malayan” region.

Quaternary sedimentology and prehistory on the Mediterranean coastal plain of Israel

The coastal plain of Israel is composed primarily of Nile-derived quartz sand carried northward in the Nile Littoral Cell and partly windblown on land. Occasional clay and gravel deposits originated in the mountains to the east are confined to the eastern end of the plain. The windblown sand was subsequently consolidated by CaCO3, probably supplied mainly by shell fragments carried with the sand. Intervals between episodes of sand deposition gave sometimes rise to pedogenic process, coupled by the influx of atmospheric dust carrying silt/clay particles from the west, south and east. Normally mature reddish-brown loams (=hamra soils) were formed. Occasionally, immature, gray-brown sandy soils of the Regosol type have formed. A few red-brown hamra soils contain archaeological remains, but cultural remains are absent from all sandy sediments or immature sandy soils.The coastal plain consists of two distinct parts: The eastern part is made of Early and Middle Pleistocene deposits while the western part contains Upper Pleistocene and Holocene deposits. The western part is characterized by several elongated, shore-parallel aeolianite ridges distributed on- and off-shore. Such ridges are absent in the eastern part of the coastal plain. On the other hand, unconsolidated sands form a considerable volume of the deposits in the eastern part but hardly exist in the western part. In the eastern part of the coastal plain there are numerous Lower Palaeolithic sites dated 1.2–0.2 My. The western part includes sites stretching from the Middle Palaeolithic (ca. 200 Ky ago) to the Chalcolithic period (ca. 5 Ky ago). The Mount Carmel coast is unique in the preservation of off-shore sites dated between the 9th to the 5th millennia BP, submerged between 12 m below sea level and the waterline. Human skeletal remains were not found on the coastal plain except in these submerged sites.

On the meaning of the terms “glaciation” and “interglacial” in the framework of studying paleoclimatic records from the Pleistocene continental and deep-water deposits

The terms “glaciation” and “interglacial” are considered from the point of view of palaeoclimatic proxies obtained from the Pleistocene deep-water and continental deposits. It is shown that the crucial factor in substantiation of these notions is determination of the cause-and-effect mechanism in the considered climatic oscillations. It is noted that oxygen isotope data on deep-water deposits have an undoubted advantage because a more accurate quantitative estimate of climatic oscillation parameters can be made on their basis. It is concluded that the role played by quantitative estimates of palaeoclimatic changes, represented by, first of all, amplitude and time characteristics of climatic oscillations, will become more significant as the methods of paleogeographic studies of both continental and deep-water deposits of the Pleistocene improve; in contrast, the formal determination of the rank of palaeoclimatic oscillations will become less significant. Special attention is paid to the cases of misfits between the Pleistocene deep-water and continental paleoclimatic records and to the necessity to make them consistently as good as possible, especially in the case of Early Pleistocene deposits.

Tunnel valley deposits from the southern North Sea – material provenance and depositional processes

This study offers new insights into the origin and depositional history of the mixture of sediments infilling one of the largest offshore, northward‐orientated, clinoform‐structured, tunnel valleys (TVs) of Elsterian age in the southern North Sea (SNS). Specifically, the study sheds light on the provenance of TV deposits based on K‐Ar dating of illite, QEMSCAN® heavy mineral assemblage study, and U‐Pb and fission track dating on single grains of apatite. Early Pleistocene substrate and the TV infill demonstrate provenance from the Scandinavian and Baltic realms as well as from Renish central Europe and the Alps. Prior to Elsterian glaciation fluvial transport to the SNS increasingly switched from Baltic sources to a more central European influence. However, based on similar provenance of both the substrate and TV infill, the episode of subglacial tunnel valley formation interrupted this central European influence. Glacial erosional processes associated with the expansion of the Elsterian ice sheet to the SNS reworked a large amount of sediment from the Early Pleistocene deposits of the SNS. The sediment was eventually deposited as the tunnel valley infill. Taking into account a high uncertainty related to the facies of TV sedimentary infill, which thus far has been inferred from seismic reflection surveys only, this study offers the first comprehensive set of data on the composition and provenance of the offshore Elsterian TV sediment.

Orcemys, a new genus of arvicolid rodent from the early Pleistocene of the Guadix–Baza Basin, southern Spain

A new arhizodont arvicoline rodent is described from early Pleistocene deposits of Barranco de los Conejos and Barranco del Paso in the Guadix–Baza Basin of southern Spain. The molars of Orcemys appear to represent a paedomorphic origination from a large rhizodont Mimomys. A few dental characters of Orcemys are superficially similar to those of the lagurines, but the presence of sparse cementum in reentrant folds and a Mimomys-kante formed opposite T5 on the first lower molar clearly identify Orcemys as an arvicoline. The character mosaic of Orcemys is unique among large early Pleistocene voles and the dentition of a potential ancestor probably resembled that of Mimomys medasensis with a tendency towards simplification. With Tibericola vandermeuleni and Mimomys oswaldoreigi, Orcemys represents one of the earliest experiments with arhizodonty among European voles. Including Mimomys medasensis at Barranco del Paso, this set of arvicolids redefines a previously recognized early Pleistocene MmQ1 biozone in Spain.

Imanolen Arrobia: A New Late Pleistocene Carnivore Den from the North of the Iberian Peninsula (Deba, Spain)

Abstract. A taphonomic and systematic study of an assemblage of large mammals preserved in an early Upper Pleistocene deposit in Imanolen Arrobia (Deba, northern Spain) is hereby reported. Skeletal profiles, long bone fragmentation and tooth marks reveal that carnivores transported wild goats and chamois carcasses to the cave for their consumption. The abundance of juvenile remains suggests that these carnivores preferentially preyed on immature individuals. After considering the frequencies of different carnivores in the assemblage and other taphonomic and neo-taphonomic features and, even though the wolf (Canis lupus) cannot be completely discarded, the leopard (Panthera pardus) is proposed as the plausible responsible for the hunting and transport of the ungulate remains to the cave. The bones were subsequently probably modified by foxes (Vulpes vulpes) that used the cave as a breeding den. By way of comparative data from the Cantabrian region and especially from the Basque Country, a metric study draw...

Early Pleistocene Fossil Snakes (Reptilia: Squamata) from Okinawajima Island in the Ryukyu Archipelago, Southwestern Japan

Abstract A number of fossil snake vertebrae were collected from Early Pleistocene deposits exposed on a hill surface at Gogayama, Nakijin village, Okinawajima Island, along with many other vertebrate fossils. These represent the oldest fossil records of snakes for the whole Ryukyu Archipelago. We identified each of these fossil snake vertebrae to the lowest taxonomic category possible based on diagnostic features elucidated in our previous study of extant snakes from Japan and adjacent regions. As a result, the vertebrae of at least four genera—Cyclophiops and Dinodon of the family Colubridae, Protobothrops (formerly Trimeresurus) of the family Viperidae, and Sinomicrurus of the family Elapidae—were recognized. Of these, vertebrae identified as belonging to the genus Dinodon were further divided into two distinct forms, although both resembled D. rufozonatum, an extant species that does not presently occur in Okinawajima or any of the surrounding islets in the central Ryukyus. Vertebrae identified as belo...