Hasil untuk "Paleontology"

Kenji M. Matsuzaki, Takuya Itaki, Yoshimi Kubota et al.

Abstract In this review we re-evaluated the potential of radiolarian species as palaeoceanographic proxies in the Northwest Pacific Ocean relying on 33 new samples collected since 2021, combined with already published datasets. Our re-evaluation revealed significant differences between Sea of Japan and Northwest Pacific radiolarian assemblages, leading to the exclusion of the Sea of Japan dataset for further sea surface temperature (SST) reconstructions in the Northwest Pacific. By employing factor analyses, we were able to identify four distinct radiolarian assemblages characterizing the Northwest Pacific and East China Sea as follows: the Subtropical, the Sea of Okhotsk-related subarctic, the Oyashio Current to transitional zone-related, and the coastal water assemblages. Each assemblage showed specific species associations with different water masses and SST ranges. Species like Tetrapyle circularis/fruticosa and Dictyocoryne tetrathalamus were associated with waters above 24 °C, while Lithomelissa setosa and Ceratospyris borealis were associated temperatures below 14 °C. Based on a review of the literature about modern radiolarian species blooming conditions in the Northwest Pacific, we suggest that radiolarian species-based reconstructed SSTs more likely infer summer SSTs. Applying weighted averaging partial least squares transfer function on selected radiolarian species showing strong affinities with changes in summer SST, we re-evaluated past summer SSTs at IODP Site U1429 in the northern East China Sea with high accuracy (R2 = 0.97, error margin ± 1.4 °C). Our radiolarian-based summer SST reconstruction is similar to Globigerinoides ruber Mg/Ca-based summer SSTs, though showing minor disparities during glacial periods, while constant disparities were observed with alkenone-based SST estimates at the same site, which is likely due to seasonal biases. Notably, we identified L. setosa as a potential proxy for East Asian Winter Monsoon intensity.

Alberto Collareta, Ottavia Mezzasalma, Juri Agresti et al.

The zombie worm genus Osedax Rouse et al. 2004 is part of a peculiar group of organisms that thrive at whale fall localities on the ocean floor. In addition to feeding on whale bones, extant Osedax spp. are known to feed on the bones of other marine and terrestrial mammals, birds, and reptiles, and have recently been found to also feed on shark tooth dentine under experimental conditions. The efficacy of Osedax spp. as bioeroders is such that they are thought to have significantly affected both the quantity and the quality of the marine vertebrate fossil record. Here, we report on the occurrence of single-entry borings consistent with those produced by Osedax on fossil shark teeth from the Lower Pliocene offshore deposits of Tuscany, central Italy. Micro-CT investigations reveal that the worms excavated the dentine of the tooth roots, leaving the enameloid-coated crowns seemingly unaltered. The borings in question are assigned to the Osedax-related ichnogenus Osspecus Higgs et al., 2012, which to date had been found on a variety of marine vertebrate fossils, but not on shark teeth. This ichnological record provides the first fossil evidence for zombie worms exploiting shark tooth dentine and serves as a powerful demonstration that such behaviour can and does occur in the wild. Root exploitation by Osedax may contribute to explain the high frequency of rootless teeth in some shark tooth accumulations from modern deep-sea floors and time-averaged horizons inland. Over the past 100 million years, shark teeth have likely served as critical ecological stepping stones between remote marine vertebrate fall localities and may even have provided a suitable substrate for ancient zombie worms during the Cretaceous–Paleogene (K–Pg) extinction event.

Juliette C. L. Menon, Donald B. Brinkman, Guilherme Hermanson et al.

Abstract The early evolution of Pan-Chelonioidea (sea turtles) is poorly understood. This is in part due to the rarity of undeformed skulls of definitive early stem chelonioids. In this work, we redescribe the holotype of Nichollsemys baieri using µCT scans and segmentations of the skull. This fossil is the best 3D preserved skull of any Campanian sea turtle, and includes partial “soft tissue” preservation. Nichollsemys is morphologically similar but clearly distinct from Toxochelys spp., and both show a mosaic of plesiomorphic and derived chelonioid features. The internal cranial anatomy documents the presence of derived characters in Nichollsemys baieri that are absent in Toxochelys spp., such as the loss of the epipterygoids and the rod-like shape of the rostrum basisphenoidale. Among the numerous plesiomorphic characters is the presence of a splenial bone, which was unnoticed before. An updated phylogenetic analysis retrieves Nichollsemys baieri as a non-protostegid early stem chelonioid in a slightly more crownward position than Toxochelys latiremis. Our phylogeny includes macrobaenids and protostegids as pan-chelonioids, and we find unorthodox results for dermochelyids. Thus, although Nichollsemys baieri provides important new insights into the early morphological evolution of sea turtles, much work remains to be done. As a completely 3D preserved specimen, we included Nichollsemys baieri into a recent landmark-based skull shape dataset of turtles. Morphospace analysis reveals an intermediate position between cryptodires and crown chelonioids. Based on these data, we also predict that Nichollsemys baieri was still capable of neck retraction, constraining the loss of this trait to more crownward pan-chelonioids.

Kamil Ahmed Qureshi, Muhammad Rizwan, Hammad Tariq Janjuhah et al.

Abstract The Middle Triassic Tredian Formation is well exposed in the western region of the Salt Range. It is mostly composed of sandstone with minor alternations of shales and dolomite. This is the first integrated attempt using petrographical and geochemical features to reveal palaeoclimate during deposition of the Tredian Formation. This work sheds light on the petrographical and geochemical properties of the Tredian sandstone in order to date various layers and evaluate the palaeoclimate. The formation was sampled at two distinct stratigraphic layers for petrographic and geochemical analysis of major and trace elements. The sandstone of the Tredian Formation is sub‐feldspathic to feldspathic arenite with sub‐angular to rounded grains that are moderately to extensively sorted. The relative proportions of the quartz, feldspars and lithoclasts in the examined sandstone samples shows that the Tredian sediments originated from the interior of the craton during a transitional continental regime. Chemical index of alteration values of 59, chemical index of weathering values of 67, and plagioclase index of alteration values of 74.5 indicate a low to moderate degree of weathering in the Tredian sediment source region. Based on the silica content, SiO2/Al2O3 ratios (2.7–6.1; mean 4.1), and chemical maturity index, it is deduced that the Tredian Formation was deposited in chemically immature to sub‐mature and dry to semi‐arid conditions. Geochemical proxies indicate the acidic source of sediment and deposition on the passive margin of the Indian Plate. The trace element characteristics of the sediments, especially the Rb/Sr, Cu/Zn, Ni/Co, V/Cr and Sr/Ba ratios, indicate that the sediments originated from the first weathering cycle and support the notion that they were deposited in an oxidising continental environment. A semi‐arid to arid palaeoclimate predominated through the Middle Triassic at the north‐western passive continental margin of the Indian Plate in the south‐eastern Neo‐Tethys.

Haidar Salim Anan

Twenty-four diagnostic Paleocene benthic foraminiferal species of Anan, which related to eighteen genera were erected from five widely separated countries in the Southern and Northern Tethys, its proposed evolutionary trends of them, and the taxonomic revision of these taxa, which will greatly aid paleontologists and biostratigraphers to helpfully understanding. Thirteen species of them were erected from Egypt ((Siphogaudryina strougoi, Pseudoclavulina hewaidyi, P. youssefi, Annulofrondicularia bignoti, Tristix aubertae, Lenticuzonaria misrensis, Percultazonaria alii, P. ameeri, Palmula berggreni, P. salimi, Vaginulinopsis boukharyi, Citharina plummerae, Gyroidinoides luterbacheri), five species from UAE (Repmanina mazeni, Psammolingulina bahri, Laevidentalina hudae, Hemirobulina olae, Ramulina futyani), three species from Pakistan (Textularia haquei, Spiroloculina haquei, S. pakistanica), two species from Jordan: (Pseudoclavulina futyani, Lenticuzonaria hodae), and one species of them is recorded from Tunisia (Leroyia tunisica). The paleogeographic distribution of these taxa are recorded in some other countries in the Southern and Northern Tethys than the original type locality, e.g. Iran, Czech, Bulgaria and Argentina. Some of these species are used to introduce an evolutionary trend marked by changes in the morphology and other characters of these benthic foraminiferal test. The Southern Tethys assemblage indicates an open marine environment, which represents middle-outer neritic environment and shows an affinity with Midway-Type Fauna (MTF).

Caroline Pessoa-Lima, Jonas Tostes-Figueiredo, Natalia Macedo-Ribeiro et al.

Molecular information has been gathered from fossilized dental enamel, the best-preserved tissue of vertebrates. However, the association of morphological features with the possible mineral and organic information of this tissue is still poorly understood in the context of the emerging area of paleoproteomics. This study aims to compare the morphological features and chemical composition of dental enamel of extinct and extant terrestrial vertebrates of Crocodylia: <i>Purussaurus</i> sp. (extinct) and <i>Melanosuchus niger</i> (extant), and Rodentia: <i>Neoepiblema</i> sp. (extinct) and <i>Hydrochoerus hydrochaeris</i> (extant). To obtain structural and chemical data, superficial and internal enamel were analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (SEM-EDS). Organic, mineral, and water content were obtained using polarizing microscopy and microradiography on ground sections of four teeth, resulting in a higher organic volume than previously expected (up to 49%). It is observed that both modern and fossil tooth enamel exhibit the same major constituents: 36.7% Ca, 17.2% P, and 41% O, characteristic of hydroxyapatite. Additionally, 27 other elements were measured from superficial enamel by inductively coupled mass spectrometry (ICP-MS). Zinc was the most abundant microelement detected, followed by Pb, Fe, Mg, and Al. Morphological features observed include enamel rods in the rodent teeth, while incremental lines and semiprismatic enamel were observed in the alligator species. The fossil enamel was in an excellent state for microscopic analyses. Results show that all major dental enamel’s physical, chemical, and morphological features are present both in extant and extinct fossil tooth enamel (>8.5 Ma) in both taxa.

Alison M Murray, Hallie Street, Robert B. Holmes

Abstract volume for 2021 virtual online meeting of the Canadian Society of Vertebrate Palaeontology

LUNG S. CHAN, ALESSANDRO MONTANARI, WALTER ALVAREZ

We have determined the magnetostratigraphy in eight Upper Cretaceous to Eocene sedimentar y sections in the Umbria and Marche Region of the Northern Apennines, Italy. Paleomagnetic samples were collected at roughly 1 m intervals from the sections studied. Both alternating field and thermal demagnetization were carried out. Microfossils in the specimens were studied to facilitate identification of the magnetic polarity intervals. We have used the combined paleomagnetic and paleontological results in conducting a high—resolution correlation and in reconstructing the paleobasin tectonic history. The magnetostratigraphic results from this study contribute to the understanding of three aspects

Sinjini Sinha, Don B Brinkman, Alison M. Murray

            Isolated centra of members of the Esocidae occur frequently in vertebrate microfossil localities of Late Cretaceous and early Paleocene age and are an important source of data on the early history of the family. However, morphological variation along the vertebral column can lead to incorrect interpretations of diversity if they are not recognized. To facilitate the use of centra for interpreting the diversity and distribution of esocids in Cretaceous vertebrate microfossil localities, the variation along the column in five extant species of esocids is described. Comparison with Cretaceous centra referred to the Esocidae allows identification of a series of features in which species of Esox differ from basal members of the family. These include the presence of a mid-ventral groove bordered by a pair of low budges on centra in the anterior end of the column, and antero-lateral processes on the posterior abdominal and anterior caudal centra. These differences provide a basis for recognizing early occurrences of the genus Esox in the fossil record and thus will allow centra to be used to document the timing of origin of the genus.

Juan Wang, Long-Yi Shao, Hao Wang et al.

The first SHRIMP zircon U–Pb ages from coal beds close to the end-Permian mass extinction are reported from the C1 coal seam in the Yantang Mine in Laibin Town, Xuanwei County, eastern Yunnan Province. Zircons were extracted from kaolinite claystone layers, defined as tonsteins (volcanic ash deposits), in the sub-seam B1 and B3 of the coal seam C1. The U–Pb ages are 252.0 ± 2.3 Ma and 250.3 ± 2.1 Ma for the sub-seam B1 and B3, respectively. Within analytical uncertainties, these U–Pb ages include the time period of the onset of the mass extinction at 251.941 ± 0.037 Ma, which was obtained from the marine Meishan section in Zhejiang Province, ∼1600 km away from the Yantang Mine. These new ages represent not only the first and closest ages to the PTB mass extinction in terrestrial coal beds, but also ages from the nearest site to the Emeishan volcanoes investigated so far. Therefore these new data provide the most accurate stratigraphic horizon of terrestrial facies of the end-Permian extinction in South China. The Emeishan volcanoes were likely the source of volcanic ash in the coal seams at the Xuanwei County and broader areas in South China. Furthermore, the minerals and geochemistry characteristics of the C1 coal seam also implied the influences of contemporaneous volcanic activities. Keywords: PTB mass extinction, C1 coal seam, SHRIMP U–Pb isotope age, Xuanwei County, Yunnan Province

Anderson Aires Eduardo, Pablo Ariel Martinez, Sidney Feitosa Gouveia et al.

Historically, studies aimed at prospecting and analyzing paleontological and neontological data to investigate species distribution have developed separately. Research at the interface between paleontology and biogeography has shown a unidirectional bias, mostly focusing on how paleontological information can aid biogeography to understand species distribution through time. However, the modern suit of techniques of ecological biogeography, particularly species distribution models (SDM), can be instrumental for paleontologists as well, improving the biogeography-paleontology interchange. In this study, we explore how to use paleoclimatic data and SDMs to support paleontological investigation regarding reduction of taxonomic uncertainty. Employing current data from two neotropical species (Lagostomus maximus and Myocastor coipus), we implemented SDMs and performed model validation comparing hindcasts with dated fossil occurrences (~14k and ~20k years back present, respectively). Finally, we employed the hindcasting process for two South American fossil records of a misidentified species of caiman (Caiman sp.) to show that C. latirostris is the most likely species identity of these fossils (among four candidate species: C. latirostris, C. yacare, C. crocodilus, and Melanosuchus niger). Possible limitations of the approach are discussed. With this strategy, we have shown that current developments in biogeography research can favour paleontology, extending the (biased) current interchange between these two scientific disciplines.

Matthew J. Vavrek, Alison M. Murray, Phil R. Bell

Xiphactinus is one of the largest teleost fish known from the Late Cretaceous of North America, and has been found across much of the Western Interior Basin. Despite extensive Late Cretaceous marine deposits occurring in Alberta, there has previously been only two possible records of Xiphactinus from the province, neither of which has been diagnosable to the species level. We describe here a portion of the lower jaws, including teeth, of Xiphactinus audax from northeast of Grande Prairie, Alberta. The fossil has large, thecodont teeth that are circular in cross section and lack any carinae, and are highly variable in their overall size. This fossil is the first diagnostic material of X. audax from Alberta, and extends the range of the species by over a thousand kilometres. During the Late Cretaceous, the area the fossil was found in was near the Arctic Circle, and represents an important datapoint within the poorly known, northern portion of the Western Interior Basin.

Kvaček Zlatko

New compression leaf material of Ceratozamia (Zamiaceae) has been recognised in the European Cenozoic. A leaflet of Ceratozamia floersheimensis (Engelhardt) Kvaček was recovered among unidentified material from the Oligocene of Trbovlje, former Trifail, Slovenia, housed in old collections of the Austrian Geological Survey, Vienna. It is similar in morphology and epidermal anatomy to other specimens previously studied from the lower Oligocene of Flörsheim, Germany and Budapest, Hungary. A fragmentary leaflet assigned to C. hofmannii Ettingsh. was recovered in the uppermost part of the Most Formation (Most Basin in North Bohemia, Czech Republic) and dated by magnetostratigraphy and cyclostratigraphy to CHRON C5Cn.3n, that is, the latest early Miocene. It yielded excellently preserved epidermal structures, permitting confirmation of the generic affinity and a more precise comparison with this lower Miocene species previously known from Austria (Münzenberg, Leoben Basin) and re-investigated earlier. Both the Oligocene and Miocene populations of Ceratozamia are based on isolated disarticulated leaflets matching some living representatives in the size and slender form of the leaflets. Such ceratozamias thrive today in extratropical areas near the present limits of distribution of the genus along the Sierra Madre Orientale in north-eastern Mexico, in particular C. microstrobila Vovides & J.D. Rees and others of the C. latifolia complex, as well as C. hildae G.P. Landry & M.C. Wilson (“bamboo cycad”). The occurrence of Ceratozamia suggests subtropical to warm-temperate, almost frostless climate and a high amount of precipitation. The accompanied fossil vegetation of both species corresponds well with the temperature regime. While the Oligocene species in Hungary probably thrived under sub-humid conditions, the remaining occurrences of fossil Ceratozamia were connected with humid evergreen to mixed-mesophytic forests.

Christy Anna Hipsley, Johannes eMüller, Johannes eMüller

Molecular-based divergence dating methods, or molecular clocks, are the primary neontological tool for estimating the temporal origins of clades. While the appropriate use of vertebrate fossils as external clock calibrations has stimulated heated discussions in the paleontological community, less attention has been given to the quality and implementation of other calibration types. In lieu of appropriate fossils, many studies rely on alternative sources of age constraints based on geological events, substitution rates and heterochronous sampling, as well as dates secondarily derived from previous analyses. To illustrate the breadth and frequency of calibration types currently employed, we conducted a literature survey of over 600 articles published from 2007 to 2013. Over half of all analyses implemented one or more fossil dates as constraints, followed by geological events and secondary calibrations (15% each). Vertebrate taxa were subjects of nearly half of all studies, while invertebrates and plants together accounted for 43%, followed by viruses, protists and fungi (3% each). Current patterns in calibration practices were disproportionate to the number of discussions on their proper use, particularly regarding plants and secondarily derived dates, which are both relatively neglected. Based on our survey, we provide a comprehensive overview of the latest approaches in clock calibration, and outline strengths and weaknesses associated with each. This critique should serve as a call to action for researchers across multiple communities, particularly those working on clades for which fossil records are poor, to develop their own guidelines regarding selection and implementation of alternative calibration types. This issue is particularly relevant now, as time-calibrated phylogenies are used for more than dating evolutionary origins, but often serve as the backbone of investigations into biogeography, diversity dynamics and rates of phenotypic evolution.

Paulo José Mota da Silva, Adriana Maria Coimbra Horbe, Marco Antonio Horbe

In six of almost fifty occurrences identified to now in Apuí, Novo Aripuanã and Manicoré municipalities, southeast Amazonas State, the manganese is hosted as lenses, laminations and layers in red sandstones, siltstones and mudstones, as well as in manganese lateritic crusts and colluvium accumulations. Romanechite is the main ore mineral, but manjiroite, lithiophorite, hollandite, vernardite, cryptomelane and pyrolusite are also present. There are two main geochemical associations: 1) for manganesiferous material: a) Sr, Au, U, Cu, Pb and Hg as in the Zé Julião occurrence; b) CaO, K2O, Zn, Tl, Rb, Cd, P2O5 and As in the Silva e Floresta farms occurrences; c) MnO, Ni, Mo, Be, Co, Ga and Eu, in the Beneficente, Cotovelo and Holanda occurrences; 2) for the sedimentary rocks, matrix and soil: d) Y + ETR - Eu; e) SiO2, Al2O3, TiO2, Nb, Hf, Zr, Fe2O3, Sc, Th, V. The genesis of the manganese oxy-hydroxides is related to deposition in sedimentary environment and to the subsequent processes of weathering and landscape evolution of the region.

Marcelo Ferreira de Vasconcelos, Sidnei de Melo Dantas, José Maria Cardoso da Silva

Knowledge of the avifaunal composition of Amazonian savannas is important in facilitating a greater understanding of thepatterns of evolution of the regional biota. Despite this, this vegetation type has been poorly sampled in comparison to adjacentrainforest habitats. The aim of this paper is to provide an avifaunal inventory of the savannas and other adjacent habitats ofMonte Alegre, on the left bank of Amazon River, northwestern Pará, Brazil. Our survey is based both on our own fieldworkand on previously-collected specimens deposited in museums. A total of 300 bird species have been recorded in the region.Ninety-four species (31.3%) were restricted to a single habitat type, indicating that habitat heterogeneity is important to theoverall species richness. Despite the fact that the Monte Alegre savannas present typical species restricted to this habitat,several open-country birds that occur in larger savanna areas located on the borders of Amazonia (along the Atlantic coastand close to the ‘cerrado’ boundaries) were not recorded in this area. Although Monte Alegre is species impoverished relativeto other savanna regions in the Amazon basin, the Monte Alegre savannas shelter the Sulfur-breasted Parakeet (Aratingamaculata), a vulnerable species in Pará state that is only known from the Guianan area of endemism (Aleixo et al., 2011). Wealso comment on biogeography, taxonomy, noteworthy records, natural history and conservation of the regional avifauna.

Diogo Jorge de Melo, Ana Carolina Fortes Bastos, Vanessa Maria da Costa Rodrigues et al.

Herein is described the development of a ludical activity in Paleontology with the purpose to apply the concepts of the geological time and the processes that occurred along the history of the Earth. This activity,that was teste in the event “Bio na Rua” of the Universidade Federal do Rio de Janeiro, consisted on the use ofdidactic panels concerning paleontological themes, geological time chart, fossil and ichnofossil concepts, the development of a board game showing the Earth history and origami workshops.

CRISTIANO LARGHI, MARCO BALINI, VALENTINA TORTI

The bivalve Daonella Mojsisovics, 1874 is very common in the Middle Triassic pelagic facies, whereas the record of this genus from shallow water limestones is rare. In the present paper a new species of Daonella, named D. pseudograbensis, is described from the Esino Limestone, a Ladinian (Middle Triassic) carbonate platform in the central Southern Alps. The species is described from Brembana Valley, where the Esino Limestone is rather rich in bioclastic lenses yielding faunas with bivalves, cephalopods, gastropods, brachiopods, corals and calcareous algae. Daonella pseudograbensis n. sp. is based on very well preserved specimens, which are often articulated and closed, all coming from the same locality. The new species shows a narrow range of intraspecific and ontogenetic morphologic variations. It is easy distinguishable from the other species of the genus for the outline and ornamentation; it therefore differs from D. grabensis Kittl, 1912, the most similar species, for the longer anterior dorsal margin.Pdf

GIULIO PAVIA, ROBERTO LANZA, FRANCESCA LOZAR et al.

This paper deals with a definition of the lower boundary stratotype of the Tithonian Stage in the Upper Jurassic succession of Monte Inici, Western Sicily. The upper member of the Rosso Ammonitico Fm. is 27 m thick and shows a typical nodular-calcareous lithofacies; its lower beds have been sampled for biostratigraphic and paleomagnetic purposes. Though the succession is affected by high stratigraphic condensation, the resulting hiatuses have been shown to be below biochronological resolution and thus do not hinder any biostratigraphic definition. The biostratigraphic analysis has been based on the rich ammonite assemblages in which the common genus Hybonoticeras is the index-key for characterizing the Kimmeridgian-Tithonian boundary. Four ammonite biozones have been identified; the basal Tithonian one is defined by the assemblage of Hybonoticeras gr. hybonotum and Haploceras staszycii. The recorded calcareous nannofossil bioevents allow recognition of the V. stradneri and C. mexicana Zones, whose boundary is located a little below the identified Tithonian lower boundary. The paleomagnetic record shows normal polarity in the S. darwini/V. albertinum Zone and mainly reverse polarity in the H. beckeri and H. hybonotum Zones, with three minor normal polarity intervals; the lower boundary of the Tithonian falls in the oldest of these intervals. The integrated multidisciplinary stratigraphic information gathered from the Contrada Fornazzo section defines the lower boundary of the H. hybonotum Zone at the base of Bed 110, and supplies elements of chrono-correlation sufficient to regard this section as a possible G.S.S.P. of the Tithonian Stage.