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1.
In the Netherlands, Late Palaeozoic pelmatozoans – that is, stalked echinoderms – are known from building stones and cobbles in rivers, but there are no in-situ carbonate rocks from which they might be collected. Unsurprisingly, most recognisable specimens are columnals and pluricolumnals. Two small thecae, collected in the mid-1970s from silexite cobbles in the bedload of the River Maas in the Venlo-Tegelen area (province of Limburg, south-east Netherlands) are exceptional finds. One specimen, the diplobathrid camerate crinoid Rhodocrinites sp., has an unsculptured theca and some minor differences of form, yet otherwise satisfies the diagnosis of this genus. The other, the pentremitid blastoid Doryblastus? sp. is rather poorly preserved, yet is the first blastoid to be recorded from the Netherlands. Either or both of these specimens may be juveniles, particularly the blastoid. They are unlikely to be coeval, coming from separate cobbles and being of slightly different preservation. Their provenance from silexite cobbles suggest they originated from Lower Carboniferous (Tournaisian-Visean = Mississippian) carbonates in the southern Ardennes (south-central Belgium).  相似文献   

2.
A collection of numerous crinoid pluricolumnals from the uppermost Darriwilian (Middle Ordovician) of Tibet were derived from one biological species of crinoid. The specimens were collected from well‐lithified, bioclastic shelf limestones of the upper part of the Lower Chiatsun Group, Pygodus serra Biozone; coeval rocks of similar lithology outcrop at the summit of Everest. A new crinoid morphospecies, Segmentocolumnus (col.) hanshessi, is tentatively considered a ‘stem‐group cladid’, perhaps a dendrocrinid. The proxistele is broad and pentagonal in section with a broad, pentagonal axial canal; the mesistele of similar gross morphology is more slender with a regularly heteromorphic column and a similarly wide axial canal; the dististele is a terminal dendritic radice with a pentastellate axial canal. In the mesistele, the meric sutures correspond to the centres of the sides of the column, but in the dististele they occur in the angles. This range of morphologies would have led to their inclusion in at least two morphogenera if they had not been closely associated; as they belong to a single biological species, they have been ‘lumped’ together herein. This is a rare contribution to our knowledge of the early crinoids from a region outside Europe and North America. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

3.
Trace fossils are described here from the Adigrat Sandstone formation of hitherto uncertain Palaeozoic-Mesozoic age in south-central Eritrea. The formation is subdivided into a lower unit, the Adi MaEkheno Member, and an upper informal unit, Member 2. The formation was deposited on the locally mudcracked top of the glacigenic Edaga Arbi Beds, suggesting that these two rock units were formed in a very short time interval. The Adi MaEkheno Member and the lower part of Member 2 contain trace fossils Arthrophycus alleghaniensis (Harlan), Arthrophycus ?brongniartii (Harlan), Didymaulichnus lyelli (Rouault), Palaeophycus tubularis Hall, Taenidium isp., thin winding ridges, winding ridges and furrows, simple cylinders, and ‘stellate’ forms. A. alleghaniensis is distinctively of Ordovician–Silurian (?Early Devonian) age. The trace fossil association belongs to the Cruziana ichnofacies that indicates a shallow marine environment between the normal and storm wave bases. The trace fossil data and stratigraphic relationships indicate that the Adigrat Sandstone formation and the Edaga Arbi Beds in Eritrea are Ordovician–Silurian in age. The Edaga Arbi Beds are correlated with other Upper Ordovician (Hirnantian) glacial units in northern Africa and the Arabian Peninsula, lending these beds the status of a marker unit in the Lower Palaeozoic stratigraphy of the Horn of Africa. The Jurassic “Adigrat Sandstone” in central-west and eastern Ethiopia cannot be correlated with the Adigrat Sandstone formation in its type area and in Eritrea.  相似文献   

4.
Nineteenth-century references to clavate borings in woody substrates in the Lower Greensand of the Isle of Wight used a variety of names, but Teredo (a wood-boring bivalve, not a boring), Teredolithes (a junior synonym of Teredolites) and Gastrochaena (a bivalve borer of rock and shelly substrates, not a boring in wood) are all nomenclatorially incorrect. Borings in a beach clast derived from the Lower Greensand Group and recently collected from Sandown Bay, Isle of Wight, are referred to Teredolites isp. cf. T. longissimus Kelly and Bromley. This specimen confirms the presence of Teredolites in the Lower Greensand Group and demonstrates a common ichnological problem of beach clasts; borings, either fossil or modern, are incompletely preserved, making confident classification below the level of ichnogenus problematic.  相似文献   

5.
The Mission Paléoanthropologique Franco-Tchadienne (MPFT) found a new species of Orycteropodidae (Mammalia, Tubulidentata) in the Kollé fossiliferous sector, northern Chad. After Orycteropus abundulafus [Journal of Vertebrate Paleontology 20 (1) (2000) 205–209; Lehmann, T., Vignaud, P., Likius A., Brunet M., in press. A new Orycteropodidae (Mammalia, Tubulidentata) in the Mio-Pliocene of Northern Chad. Zool. J. Linnean Soc.], this specimen is the second complete skeleton of fossil aardvark found in the Djurab desert. It is the first complete representative of an Orycteropus species found in the Pliocene of Africa. In regard to the Miocene fossil aardvarks, this new taxon, Orycteropus djourabensis nov. sp., shows more affinities with the extant O. afer. The main differences are the larger teeth and the shorter hand in the fossil form. Kossom Bougoudi and Kollé represent a chronological series that gives a unique opportunity for studying the evolution of the African Tubulidentata around the Mio-Pliocene boundary (5.5-4 My). The new species is distinct from the older Chadian Orycteropodid from KB and it embodies the taxonomic turnover that took place within the order Tubulidentata around this boundary in Africa. Moreover, this new species is the oldest known Orycteropus species that clearly belongs to the modern forms including the extant aardvark.  相似文献   

6.
A new partial skeleton of the armoured ornithischian dinosaur Polacanthus found in the Wadhurst Clay Formation (Valanginian stage) of Bexhill, Sussex is the oldest recorded occurrence of this taxon. Previous discoveries suggested that at least two armoured ornithischians occur in the Wealden succession: Polacanthus, which was mostly restricted to the Barremian, and Hylaeosaurus, which was recorded as present only in the Valanginian. The new discovery extends the stratigraphic range of Polacanthus into the Valanginian. Although these two taxa appear to be closely similar anatomically, their osteology now suggests they are not synonymous. The new specimen includes the first known jugal as well as a comparatively rare polacanthid plate/spine (splate) which probably comes from the shoulder (pectoral) area of these animals.  相似文献   

7.
The palaeontological content (charophytes and vertebrates) of organic-rich layers from the Middle Jurassic (Bathonian) of the Grands Causses at Mostuéjouls (Aveyron, France) has been examined. It is rich in gyrogonites of Porochara douzensis. The vertebrates of the lower layer include a single hybodontiform tooth, “semionotiform” teeth and scales, and one pycnodontiform tooth whereas the upper layer has yielded one hybodontiform tooth, a variety of actinopterygian remains (mostly Caturus sp. and indeterminate pycnodontiforms) and a few possible reptile remains. The variation in fauna between the two layers is ascribed to a different degree of marine influence.  相似文献   

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9.
Palaeolithic people commonly hunted Equus hydruntinus, an extinct species of equid whose cursorial body proportions suggest an adaptation to semi-arid conditions. Despite the frequency with which it is encountered in fossil deposits, only partial cranial remains have been reported until now. As a result, the systematic affiliation of the species remains a subject of controversy. Two nearly complete E. hydruntinus crania are presented here for the first time. These skulls show that E. hydruntinus is a distinct species, more closely related to the hemiones (Asiatic asses) than to any other equid. This suggests that the social organisation of E. hydruntinus followed one of two known equid sociotypes: resource defense territoriality.  相似文献   

10.
Two gigantic individuals of the puzosiine ammonite genus Pachydesmoceras, from uppermost Middle and lower Upper Turonian strata in central and southwest Poland, are described and illustrated as the first examples of this genus to be recorded from Poland. Specific identification is problematic because of internal mould preservation and deformation to various extent; in addition, comparative material from other European localities is lacking. Representatives of Pachydesmoceras are typical of the Tethyan Realm; records from the European and Northwest Pacific provinces in the Boreal Realm are few. Both Polish specimens are referred to as P. cf. pachydiscoide Matsumoto.  相似文献   

11.
The Late Oligocene oyster Hyotissa antiguensis (Brown) is locally common in the Antigua Formation of Hughes Point, eastern Antigua, Lesser Antilles; it was not commonly bored at that time. Its valves and shells are robust, and reworked into the shallow water near-shore environment in Antigua; it could potentially be incorporated into younger rocks. Its neoichnology includes clues that would facilitate identification of these oysters as reworked fossils. The suite of modern borings found in these specimens includes common Caulostrepsis taeniola Clarke, Gastrochaenolites isp. cf. G. turbinatus Kelly and Bromley and Entobia isp., and rare Oichnus simplex Bromley and Rogerella? isp. The latter three taxa are limited to oyster shell substrates. Of the common ichnotaxa, Caulostrepsis and Gastrochaenolites are particularly prominent in limestone clasts and limestone cemented to oyster shells, which would be an indicator of reworking if found in a post-Oligocene lithified deposit. Caulostrepsis and Gastrochaenolites are relatively less common in oyster shells and valves, and in many specimens are seen to terminate against the shell. Entobia is the only common boring limited to the shell substrate. The fidelity of preservation of modern borings is also superior in limestone clasts. This suite of borings is comparable with those found in the Neogene of the Antillean region.  相似文献   

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14.
A Bison antiquus cranium and partial skeleton from Ayer Pond wetland on Orcas Island, San Juan Islands, Washington, date to 11,760 ± 70 14C yr BP. They lay in lacustrine sediments below peat, unconformably above emergent Everson Glaciomarine Drift (> 12,000 14C yr BP). Several bison finds in similar contexts on Orcas and Vancouver Islands dating between 11,750 and 10,800 14C yr BP indicate an early postglacial land mammal dispersal corridor with reduced water barriers between mainland and islands. New bison dates and published shell dates allow estimation of early postglacial relative sea-level trends for the San Juans, with a drop below modern datum ∼ 12,000 14C yr BP, and assist in evaluation of marine reservoir corrections. Emergence by ∼ 60 m is suggested by data from nearby areas. A tundra-like or meadow community and succeeding open pine parkland before 11,000 14C yr BP supported bison but horn-core reduction suggests suboptimal forage or restricted habitat. Expanding mixed-conifer forests after 11,000 14C yr BP contributed to bison extirpation. Dispersing ungulates such as bison must have influenced island vegetation establishment and early succession. Possible evidence for butchering by early coastal people adds significance to the Ayer Pond discovery, given its pre-Clovis age.  相似文献   

15.
Twelve fossil species of Proteaceous pollen, predominantly attributable to Proteacidites and Beaupreaidites, were recovered from the Maastrichtian-Paleocene sedimentary succession of the Garden Cove Formation on Campbell Island, the southernmost landmass of the Zealandia continent. Among these are two new species, Proteacidites campbellensis and Proteacidites hortisinus. The high diversity of Proteaceae pollen in the sediments encompassing the Cretaceous-Paleogene boundary on Campbell Island is consistent with the fossil record from neighbouring landmasses but strongly contrasts with the impoverished record of the family in the extant New Zealand flora. Examples of Beauprea- and Knightia-like pollen in the Campbell Island assemblages confirm the presence of these lineages on Zealandia by the end of the Cretaceous and suggest that their present endemism in New Caledonia and New Zealand can be explained in terms of relictual vicariant distributions, perhaps modified by northward tracking of warmer climates on Zealandia through the Cenozoic.  相似文献   

16.
The abundance of sedimentary organic material from two lakes was used to infer past Holocene storminess on Adak Island where frequent storms generate abundant rainfall and extensive cloud cover. Andrew and Heart Lakes are located 10 km apart; their contrasting physical characteristics cause the sedimentary organic matter to respond differently to storms. Their records were synchronized using correlated tephra beds. Sedimentation rates increased between 4.0 and 3.5 ka in both lakes. Over the instrumental period, Andrew Lake biogenic-silica content (BSi) is most strongly correlated with winter sunlight availability, which influences photosynthetic production, and river input, which influences the dilution of BSi by mineral matter. Heart Lake BSi is likely affected by wind-driven remobilization of sediment, as suggested by correlations among BSi, the North Pacific Index, and winter storminess. The results indicate relatively stormy conditions from 9.6 to 4.0 ka, followed by drying between 4.0 and 2.7 ka, with the driest conditions from 2.7 to 1.5 ka. The stormiest period was between AD 500 and 1200, then drying from 1150 to 1500 and more variable until 1850. This record of Holocene storminess fills a major gap at the center of action for North Pacific wintertime climate.  相似文献   

17.
New fossil remains of the proboscidean genus Anancus are described. Among them, a complete skull allows us to revisit for the first time the entire Chadian Anancus fossil record. This genus occurred in the Old World from the late Miocene up to the early Pleistocene. The analysis of dental and cranial characters was allowed individual variations from specific characters to be distinguished. In this study we show that Anancus kenyensis and Anancus osiris are very likely synonym taxa which leads us to emend the diagnosis of A. kenyensis. In addition, this study shows that dental characters in anancines lineage are of little significance for biostratigraphical inference, by contrast to previous works. This study brings new data about the phylogenetical and palaeobiogeographical history of the African anancines.  相似文献   

18.
Three robust tree-ring density chronologies were developed for the western Tianshan Mountains of northwestern China. The chronologies were significantly correlated and form a regional chronology (GLD). The GLD had significant and positive correlations with temperature of warm seasons. Based on this relationship, the mean minimum temperatures of May to August were reconstructed using the GLD chronology for the period AD 1657 to 2008. The temperature reconstruction exhibited temperature patterns on interannual to centennial timescales, and showed that the end of the 20th century is the warmest period in the past 352 years. The reconstructed temperature variation has a teleconnection with large-scale atmospheric–oceanic variability and captures long- and broad-scale regional climatic variations.  相似文献   

19.
Borehole 2506 drilled in the northern area of the Arkhangelsk Oblast penetrated through the Paleozoic sedimentary block isolated in the Vendian thick sequence. A diverse acritarch assemblage has been established within the depth interval of 119.9–217.5 m. The assemblage comprises more than 70 taxa, including species characteristic of the boundary interval between the Volkhov and Kunda horizons of the East European Platform (the graptolite Didymograptus hirundo Zone). Stratigraphic position of host deposits was established within the Darriwilian Stage of the Middle Ordovician. The described assemblage of microphytofossils is similar to coeval assemblages from NW Russia, Baltic region, and Scandinavia, being typical of the Baltic phytoplankton province of temperate latitudes. A great number of species in common suggests that the assemblage under consideration is correlative with coeval assemblages of southern China thus offering a possibility of remote correlation.  相似文献   

20.
Twenty-six form-species of plant macrofossils occur in the Coal Measures exposed in the Howgill Head Quarry, Whitehaven, Cumbria, UK. They belong to the Neuropteris semireticulata Subzone in the lower part of the Paripteris linguaefolia Zone, indicating the uppermost Duckmantian. They confirm that the sandstones exposed in this part of the West Cumberland Coalfield are part of the Whitehaven Sandstone Formation, and not a stratigraphically lower unit as previously suggested. The Howgill head fossils represent the only well documented example of a N. semireticulata Subzone assemblage in Britain, although comparable assemblages are known from coeval strata in northern France, Belgium, northern Germany and Poland.  相似文献   

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