Hui Dai, Xu-Feng Hu, Chao Tan et al.
Hasil untuk "Paleontology"
Menampilkan 20 dari ~22153 hasil · dari DOAJ, CrossRef
Eduard Mychko, Jiri Chlachula
The SE Baltic area, the former Eastern Prussia, is renowned for complex natural history. Over the past millions of years, the area experienced major geological events and geomorphic landscape transformations, resulting in the present relief configuration. Past climates and environments gave rise to the specific life-forms that proliferated in the Paleozoic and Mesozoic–Early Cenozoic shallow sea/lacustrine basins, and the Late Cenozoic riverine and continental settings. During the Paleogene, forested sub-tropical lands and deltaic settings of coastal sea lagoons gave rise to the famed amber formations (Blue Ground) hosting inclusions of resin-sealed insect and other small invertebrates that offer an unprecedented look into the 35–34 million-year habitats. Ferruginous sandstones, formed in shallow waters incorporating remains of thermophilous fauna—bivalves and gastropods, bryozoans, and sea urchins, among others—lie above the amber-bearing deposits. Oligocene–Miocene continental (riverine, lacustrine, and palustrine) conditions relate to the “Brown Coal Formation”, embedding a variety of fossil plants. Finally, the Quaternary Period brought dramatic geo-environmental shifts, with cyclic interstadial sea transgressions and massive glacial erosion events delivering fossiliferous erratics with an array of primitive Paleozoic and later Mesozoic life-forms. Overall, the extraordinary paleontology of the SE Baltic area adds, within its geological context, to the European geoheritage and the world natural heritage.
Rainer R. Schoch, Florian Witzmann, Raphael Moreno et al.
The Middle Triassic capitosaur Mastodonsaurus giganteus was the largest temnospondyl and the dominating aquatic predator in many European freshwater to brackish ecosystems. It is represented by numerous size classes, which are described and analysed for the first time. The documented size range encompasses specimens between 12–15 mm and 1200 mm in skull length. Early growth stages are restricted to dentaries and interclavicles, whereas juveniles are represented by partial skulls, mandibles, and girdles. The smallest specimens already possessed diagnostic features of the taxon, and small juveniles also shared the dermal ornament with larger specimens. The heavy, disc-shaped intercentra were established early in the juvenile phase. Cranial proportions were remarkably conservative throughout ontogeny, with the orbits proportionately decreasing in size only very moderately, the postorbital skull becoming slightly longer and the occipital margin more concave in the largest forms. Analysis of frequency distributions of M. giganteus in different Lower Keuper deposits in southern Germany reflects habitat preferences in specific phases of its life cycle. The coal-bearing deposit at Gaildorf yielded unusually large specimens with relatively well-ossified appendicular skeletons. In the more common lake shore facies, only adult specimens are present. In turn, juveniles might have dwelled in calmer environments. Smaller lakes were apparently less attractive than larger or deeper water bodies that provided sufficient resources for several temnospondyls, and juvenile specimens have been identified from all of them. The diverse actinopterygian fish fauna provided prey for all growth stages of the large temnospondyl predators.
Emily J. Lessner, Emily J. Lessner, Xing Xu et al.
IntroductionVertebrate sensory systems are in close contact with surrounding tissues, often leaving bony signatures behind. These bony features are the keys to assessing variation in sensory systems in fossil taxa. The trigeminal sensory system (e.g., trigeminal ganglion, ophthalmic, maxillary, and mandibular divisions) has osteological correlates throughout the skull, including the braincase (e.g., trigeminal fossa, prootic notch, ophthalmic and maxillomandibular foramina) and rostrum (e.g., mandibular canal, neurovascular foramina).MethodsHere we measured and compared these features among a morphologically, phylogenetically, and ecologically diverse sample of sauropsids to determine strength of osteological correlates and to explore ecomorphological trends. We determined several suitable osteological correlates for trigeminal soft tissue features and discounted foramen count alone as a suitable osteological correlate. However, when size was accounted for, foramen count becomes a useful indicator of sensory ecology.Results and discussionAmong extant taxa, those engaging in tactile sensory behaviors with the face exhibit relatively larger trigeminal tissues and osteological correlates than those not engaging in tactile sensory behaviors. Though patterns are unclear among several clades, both relative feature sizes and models used to predict sensory capacity reveal a trend of increasing tactile sensitivity along the pseudosuchian lineage. Overall, a quantitative assessment of ecomorphological trends of trigeminal osteological correlates proves informative for the hypotheses of sensory behavior in extinct taxa and supports the use of similar assessment methods for other osteological correlates.
Christian Klug, Timur Sivgin, Feiko Miedema et al.
Abstract Switzerland is an ichthyosaur country: it has a rich record of marine reptile fossils, particularly the fish-shaped ichthyosaurs, and the according research. Here, we provide an overview over the 12 or more genera and at least 13 species plus numerous fragmentary remains of ichthyosaurs from the Triassic to the Cretaceous that have been discovered in twelve cantons thus far, of which four species are based on Swiss holotypes. This wealth of ichthyosaur species can be explained by their abundance in the Middle Triassic conservation deposits (Konservat Lagerstätte) of Monte San Giorgio, as well as occasional discoveries in strata of Middle Triassic to Early Cretaceous age. The moderate abundance of outcrops in reasonable conditions in combination with the long history of palaeontological research in Switzerland explains this good fossil record. In addition to this unique overview, we provide more data for further studies and update the knowledge of these taxa.
Martina Aubrechtová, Vojtěch Turek, Štěpán Manda
The vast majority of cephalopods of the order Tarphyceratida are known from regions that were located at mid- or low palaeolatitudes during the Ordovician (mainly Baltica, Laurentia, and Chinese palaeoblocks). Only a handful of tarphyceratid specimens are known from high palaeolatitude regions of peri-Gondwana and Gondwana. Here, we describe the two best-preserved trocholitid cephalopods known to date from the Ordovician of the Prague Basin. The first is from the late Darriwilian/early Sandbian Dobrotivá Formation and is assigned to Trocholites fugax, a species previously recorded from roughly coeval strata of Iberia, France, and Bohemia. The specimen thus strengthens previous hypotheses regarding the interchange of non-benthic faunas between Baltica and different regions of peri-Gondwana during the Middle/ Late Ordovician boundary interval. The second specimen, assigned to a new species of Trocholites chaloupkai sp. nov., is from the late Sandbian–early Katian Zahořany Formation and thus represents one of the stratigraphically youngest Trocholites in the Ordovician of peri-Gondwana. Internal structures of the shell of the holotype of the new species were studied using micro-CT tomography. This revealed that T. chaloupkai sp. nov. closely resembles the stratigraphically older (Darriwilian) species Trocholites depressus from Estonia.
Brian Andres, Wann Langston
Marcelo R. Sánchez-Villagra
Timothy B. Rowe, Timothy B. Rowe, Thomas W. Stafford et al.
Calibrating human population dispersals across Earth’s surface is fundamental to assessing rates and timing of anthropogenic impacts and distinguishing ecological phenomena influenced by humans from those that were not. Here, we describe the Hartley mammoth locality, which dates to 38,900–36,250 cal BP by AMS 14C analysis of hydroxyproline from bone collagen. We accept the standard view that elaborate stone technology of the Eurasian Upper Paleolithic was introduced into the Americas by arrival of the Native American clade ∼16,000 cal BP. It follows that if older cultural sites exist in the Americas, they might only be diagnosed using nuanced taphonomic approaches. We employed computed tomography (CT and μCT) and other state-of-the-art methods that had not previously been applied to investigating ancient American sites. This revealed multiple lines of taphonomic evidence suggesting that two mammoths were butchered using expedient lithic and bone technology, along with evidence diagnostic of controlled (domestic) fire. That this may be an ancient cultural site is corroborated by independent genetic evidence of two founding populations for humans in the Americas, which has already raised the possibility of a dispersal into the Americas by people of East Asian ancestry that preceded the Native American clade by millennia. The Hartley mammoth locality thus provides a new deep point of chronologic reference for occupation of the Americas and the attainment by humans of a near-global distribution.
LUCA JASELLI, CHRISTOPHER J. DUFFIN
At the beginning of the Jurassic, the initial stages of the rifting that preceded the opening of the Alpine Tethys led to the establishment of the Lombardy basin, characterized by a shallow water marine palaeoenvironment inhabited by highly diversified ecological communities. Macrofossil records from the whole Lower Jurassic succession of Lombardy are currently mostly confined to invertebrates. The earliest occurrence of marine vertebrates is from the Sinemurian Moltrasio Limestone of Osteno (Varese), subsequent to the Triassic/Jurassic boundary (TJB) post-crisis recovery. Here, we describe material from the Roncola section (Roncola San Bernardo, Bergamo) of the Sedrina Limestone (upper Hettangian), consisting of a dense accumulation of crinoid skeletal remains belonging to Balanocrinus ticinensis Hess, 2006. Among them are three isolated neoselachian teeth assigned to the genus Sphenodus Agassiz, 1843. This new discovery is significant and extends our knowledge of the biodiversity of the Lombardy basin Jurassic, mainly because these dental remains represent the earliest vertebrate macrofossils ever documented from this area after the Triassic/Jurassic boundary. Sphenodus (which ranges from the Sinemurian to the Danian) is a fairly ubiquitous Sinemurian neoselachian shark but this new record moves its First Appearance Datum (FAD) back to the Hettangian stage.
Ryuji Asami, Akira Kinjo, Daiki Ohshiro et al.
Abstract The geochemistry of the calcium carbonates of marine organisms is an excellent proxy for reconstruction of the paleoceanographic history. However, previous studies of hypercalcified demosponges (sclerosponges) are considerably fewer than those of corals, foraminifers, and bivalves. Here, we investigated stable oxygen (δ18O) and carbon (δ13C) isotopes and minor and trace element (Mg, Sr, Ba, Pb, and U) to Ca ratios of 36 living sclerosponges (Astrosclera willeyana) collected from Kume Island in the Ryukyu Islands, southwestern Japan, to evaluate the utility of geochemistry as a paleoenvironmental proxy. The δ18O, δ13C, and Sr/Ca deviations of the coevally precipitated skeleton were extremely small and almost constant at all skeletal portions, strongly suggesting that within-skeletal variations in the chemical components are negligibly small for non-symbiotic sclerosponges. Mean δ18O, δ13C, and Sr/Ca values (N = 36), falling within a quite narrow range, showed no significant evidence for intraspecific (inter-specimen) variations in the sclerosponges. The sclerosponges δ18O and δ13C were consistent with those of the aragonites precipitated in isotopic equilibrium with seawater at the growth site. The sclerosponge Sr/Ca was close to that of inorganically precipitated aragonite, and the estimated partition coefficient of 1.1 (almost unity) is identical to previously reported values for different species (Ceratoporella nicholsoni). Consequently, these results suggest that A. willeyana sclerosponge, having little vital effects on the geochemistry, is a robust indicator of paleocean environments (seawater δ18O, temperature, and dissolved inorganic carbon δ13C). Further, our evaluation study documents that sclerosponges living in deeper ocean environments can support the reconstruction of spatial and vertical paleoceanographic changes in conjunction with coral proxy records. The sclerosponge U/Ca showed little within-skeletal and intraspecific variations, but the heterogeneity and individual difference of the Mg/Ca, Ba/Ca, and Pb/Ca were relatively large, the reasons of which still remain unresolved.
PATRIZIA FRAVEGA , GRAZIA VANNUCCI
The revision of holotypes and paratypes of Lithophyllum contii Mastrorilli, 1967 and Lithophyllum giammarinoi Mastrorilli, 1 968, coming from the Rupelian calcarenitic limestone of the "Molare Formation" (Tertiary Piedmont Basin), demonstrates that there are not enough elements to permit the distinction of two different species. So, according to priority, Lp. giammarinoi must be consider junior synonym of Lp. contii, that is here redescribed as Lithophyllum contii Mastrorilli sensu amplo.
ALFRÉD DULAI, FRITZ VON DER HOCHT
Upper Oligocene brachiopods of NW Germany were studied in two collections: the Naturalis Biodiversity Center (Leiden, the Netherlands) and the F. von der Hocht private Collection (Kerpen, Germany). Overall, six brachiopod taxa have been identified. Generic attributions of “Rhynchonella” supraoligocaenica Görges, 1952 (Aphelesia) and “Terebratula” pusilla Philippi, 1843 (Germanoplatidia n. gen) have been solved. The Chattian occurrence of Aphelesia is the first confirmed record of the genus in the Paleogene. Chattian record of the well-known Neogene Discinisca fallens (Wood, 1872) confirms that faunal change within brachiopods happened before the Paleogene/Neogene boundary. Similarly to the Mediterranean Terebratula-Aphelesia association, Aphelesia occurs also together with a large terebratulide genus (Pliothyrina) in the upper Oligocene Pre-North Sea. Along with some previously recognized genera (Orthothyris, Bronnothyris, Rugia), a further brachiopod evolutionary lineage was found to survive from the Mesozoic to the Paleogene (Aemula-Germanoplatidia n. gen.). According to the morphological characters of the genus and sedimentological characters of the surrounding deposits, Germanoplatidia n. gen. species lived on sandy bottom environments, and attached to small hard objects in the fine sediment by a pedicle longer than that of Aemula. Half of the identified species are endemic in Pre-North Sea. Here we document the first record of Argyrotheca bitnerae Dulai in Dulai & Stachacz, 2011 from the Pre-North Sea; this recently described species shows a cosmopolitan distribution in the Cenozoic.
Thiago Schineider Fachini, Silvio Onary, Alessandro Palci et al.
Summary: Blind snakes (Scolecophidia) are minute cryptic snakes that diverged at the base of the evolutionary radiation of modern snakes. They have a scant fossil record, which dates back to the Upper Paleocene-Lower Eocene (∼56 Ma); this late appearance conflicts with molecular evidence, which suggests a much older origin for the group (during the Mesozoic: 160–125 Ma). Here we report a typhlopoid blind snake from the Late Cretaceous of Brazil, Boipeba tayasuensis gen. et sp. nov, which extends the scolecophidian fossil record into the Mesozoic and reduces the fossil gap predicted by molecular data. The new species is estimated to have been over 1 m long, much larger than typical modern scolecophidians (<30 cm). This finding sheds light on the early evolution of blind snakes, supports the hypothesis of a Gondwanan origin for the Typhlopoidea, and indicates that early scolecophidians had large body size, and only later underwent miniaturization.
Keith Berry
In past investigations the pattern of differential survival of plants across the K/Pg boundary has been viewed as incompatible with severe asteroid impact winter scenarios (i.e., an impact winter lasting more than a few months), particularly the enigmatic survival of coryphoid palms and Pandanus (screw pine). Stateof- the-art climate models based on soot, sulfate and nano-sized dust aerosols predict a global impact winter that drastically reduced precipitation and resulted in a transient period of total darkness and permafrost conditions. This suggests that the plants most likely to have been affected by the global mass-extinction event were tropical phanerophytes that produce recalcitrant seeds, which by definition are desiccation-intolerant, survive less than a year, and cannot survive freezing. However, this hypothesis has never been tested. In this study I sampled over 100 plant species from the global fossil record that have a high probability of having produced either recalcitrant seeds/disseminules (n1 = 58) or orthodox seeds (n2 = 59), based on their phylogenetic relationships with extant taxa that either are monomorphic for these traits or specifically exhibit a genetic marker for abscisic acid inhibition associated with seed dormancy and recalcitrance. A one-tailed z-test for the difference between two proportions revealed that plant taxa with a high probability of having produced recalcitrant seeds had significantly lower survivorship than plant taxa with a high probability of having produced orthodox seeds (p < 0.0001). Based on these data, it can be concluded that plants which formed a frost-tolerant seed bank during the latest Maastrichtian were significantly more likely to survive the K/Pg impact winter than plants which did not (including palms). These data clearly indicate that the K/Pg impact winter probably lasted longer than a year and that it selected for seed-based traits that effectively sorted correlated functional traits of mature plants (i.e., leaf physiognomic features). This novel hypothesis stands as an alternative to J.A. Wolfe’s classic hypothesis that a mild K/Pg impact winter selected for fast-growing angiosperms with deciduous leaves and did not affect the plant communities of the Southern Hemisphere. Potential mechanisms for the rare survival of tropical, recalcitrant-seeded plants are discussed.
Daniel Grenard, Kenneth Carpenter, Andrew Smith et al.
The Garden Park National Natural Landmark in central Colorado U.S.A. was established for 40 acres (0.16 sq. km) by the U.S. National Park Service in 1973 in recognition of its historical and paleontological significance. It was here that rather complete dinosaur skeletons were first discovered in great abundance and diversity in the late 1800s, sparking a growth in worldwide interest in dinosaurs. The dinosaur quarries played an important part in the "Bone Wars" in the early history of American paleontology. Despite the National Natural Landmark designation, human-caused environmental deterioration continued. Not until passage of the Federal Land Policy and Management Act (FLPMA) in 1976 did the Bureau of Land Management reassess the negative environmental impacts of public lands in Garden Park. A series of studies led to incremental protection of the environment and paleontological resources, beginning with the establishment of a Research Natural Area in 1987, then a larger Area of Critical Environmental Concern in 1996, and finally a greatly expanded National Natural Landmark in 2013. The multipurpose land usage mandated by FLPMA has at times resulted in conflicting goals in Garden Park. Over time, the local BLM has gradually increased protection of the paleontological resources, geological scenery and rare plants, while also providing educational and recreational opportunities.
Zeng-Zhao Feng
During the past 30 years (1987–2016), a great progress has been made in researches of soft-sediment deformation structures (SSDS) and seismites in China. However, the research thought of the academic field was not open-minded. It was almost with one viewpoint, i.e., almost all the papers of this field published in China considered the beds with SSDS as seismites. In order to change the phenomenon of one viewpoint, Feng et al. (2016) wrote a paper “Researches of soft-sediment deformation structures and seismites in China — A brief review” as “to cast a brick to attract the jade”, emailed this paper to many geologists in China and other countries, and invited them to write papers for the symposium of “Multi-origin of soft-sediment deformation structures and seismites”, to orally present their papers at the symposium, and to discuss the problems of SSDS and seismites. “The seismite problem” by Prof. Shanmugam is the first paper that we have received from those geologists invited by us. It is an excellent paper that covers 153 years researches of geologists worldwide and has 268 references. It is beneficial to the researches of SSDS and seismites in China. The most important contribution of this paper is to challenge and negate the term “seismites” introduced by Seilacher (1969). Therefore, the term “seismites” should be obsoleted. Chinese geologist translated the term “seismites” into “震积岩” (Zhenjiyan) (the beds induced by earthquake and sedimentation). It is a mistranslated term and should not be used any more. Whether the term “seismites” should be obsoleted or not, and whether the term “震积岩” (Zhenjiyan) should not be used any more, these problems should be discussed and determined by numerous geologists in China and worldwide, and should be determined by geological practice. Another important contribution of “The seismite problem” is introduction of triggers and emphasis of liquefaction. 21 triggers and 2 types of soft-sediment constitute the theoretical foundation of the formation process of SSDS. If we utilize the method of “On contradiction” by Tse-Tung Mao (1937), study the formation process of SSDS in which there are many contradictions, and devote every effort to finding its principal contradiction, the SSDS can reveal something about the triggers, i.e., can reveal something about the origin of SSDS.
ENRICO TREVISANI
In the central-eastern areas of the Trento Platform (Asiago Plateau, Lavarone Plateau, Valsugana and Mt. Grappa) many stratigraphic sections at lower-middle Jurassic boundary have been examinated. The aim of the research was to describe the Toarcian-Aalenian sediments or their gaps in these platform areas. The crinoidal cross-bedded calcarenites (San Vigilio Oolite) whose thickness is 70 m, situated at Mt. Agaro and at Mt. Grappa, have been attributed to Aalenian. The oolitic calcarenites (Grigno Member- Calcari Grigi) which show their maximum thickness at Mt. Agaro and at Grigno have been doubtfully attributed to Toarcian.
Lindsay E. Zanno, Khishigjav Tsogtbaatar, Tsogtbaatar Chinzorig et al.
Definitive therizinosaurid cranial materials are exceptionally rare, represented solely by an isolated braincase and tooth in the North American taxon Nothronychus mckinleyi, the remarkably complete skull of the Asian taxon Erlikosaurus andrewsi, and the lower hemimandibles of Segnosaurus galbinensis. To date, comprehensive descriptions of the former taxa are published; however, the mandibular materials of S. galbinensis have remained largely understudied since their initial description in 1979. Here we provide a comprehensive description of the well-preserved hemimandibles and dentition of S. galbinensis (MPC-D 100/80), from the Upper Cretaceous Bayanshiree Formation, Gobi Desert, Mongolia. The subrectangular and ventrally displaced caudal hemimandible, extreme ventral deflection of the rostral dentary, and edentulism of the caudal dentary of S. galbinensis are currently apomorphic among therizinosaurians. Unique, unreported dental traits including lingually folded mesial carinae, development of a denticulated triangular facet on the distal carinae near the cervix, and extracarinal accessory denticles, suggest a highly specialized feeding strategy in S. galbinensis. The presence of triple carinae on the distalmost lateral tooth crowns is also unique, although may represent an abnormality. Contrasted with the simplistic dentition of the contemporaneous therizinosaurid E. andrewsi, the dentition of S. galbinensis is indicative of niche partitioning in food acquisition, processing, or resources among known therizinosaurids inhabiting Asian ecosystems in the Late Cretaceous. Although not quantitatively correlated with diet, this suite of specializations is otherwise unique among theropod dinosaurs and supports derived inferences of facultative or obligate herbivory in therizinosaurids, ultimately adding novel information to our understanding of ecomorphology in theropods.
ANTONIETTA CHERCHI, ROLF SCHROEDER, DANIELA RUBERTI
A new larger foraminifer, Cuneospirella samnitica n. gen., n. sp., from the Santonian of the Matese Mountains (central Italy) is described. This taxon, characterized by an initial planispiral, a rectilinear adult stage and the subdivision of chambers by partitions, could be descended from a morphotype like Spiroplectammina multicamerata Said & Kenawy, recorded in the upper Turonian of the Apennines (central Italy).
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