Hasil untuk "Paleontology"

Luis David Badilla Oviedo, Judith Cambronero Vega, Valery Sánchez Espinoza et al.

[Objective] This study aimed to implement 3D image acquisition and postprocessing tools for the natural heritage preservation of a collection of craniums from a zoology museum and a wildlife rescue center.  [Methodology] Samples were prepared following osteotechnics protocols developed at the rescue center. They were then digitized in a darkroom using a metrology-grade 3D scanner. Meshes were optimized for both fabrication and visualization purposes. Subsequently, some of the models were printed at a university makerspace using three different technologies to be measured and analyzed with the metrology capabilities of inspection software; the purpose was to determine which technology provided the most accurate replicas.[Results] The results demonstrated that the three technologies produced high-quality replicas. However, those based on optical processes (SLA and material jetting) generated more accurate physical models, which are of particular interest for scientific fields, such as zooarchaeology, paleontology, biology, and veterinary medicine. These fields could benefit from training and learning experiences supported by these digital asset collections. The models were successfully adapted to be uploaded to a 3D viewer platform, which is compatible with low-cost virtual reality solutions, to implement them in environmental education activities. [Conclusions] The experience demonstrates that photogrammetry and 3D scanning are feasible solutions to preserve high-value samples of scientific and historical interest composed of biological materials exposed to degradation by environmental conditions. It also provides new digital assets to foster outreach and educational activities for universities, museums, and rescue centers.

Max Engel, Anja Zander, Martin Kehl et al.

This geoarchaeological survey was dedicated to (i) the Umm an-Nar (2700–2000 BCE) settlement site of Dahwa and surrounding areas in the foothills of the Hajar Mountains as well as (ii) the coastal area near Saham on the Batinah coastal plain in northern Oman, the latter without focus on a specific cultural epoch. Stratigraphic sections from the proximal coastal plain provide insights into highly dynamic episodic sedimentation patterns with thick units of variable grain sizes and sorting. In one of the stratigraphic profiles in the town of Saham, a small anthropogenic pit or channel was found, interpreted as a pit hearth used by the Samad culture (300 BCE–100/200 CE) based on granulometry, thin-section analysis, clustered macro-charcoals, amorphous organic remains, as well as luminescence and 14C dating. Our coincidental discovery of this site indicates that there might be abundant traces of the Samad culture buried in the thick alluvium, from a period of hydrologically favourable conditions c. 50–300 CE. The Umm an-Nar dating of the Dahwa archaeological site in the foothills of the Hajar Mountains was confirmed for the first time by luminescence dating, although the low dose rate and high scatter of equivalent doses pose substantial challenges to the regional application of this method.

Bernard Lathuilière, Danwei Huang, The Corallosphere Group

The morphology of stony corals (Scleractinia) remains the only means to reconstruct the most inclusive evolutionary history of the clade comprising both extant and extinct species. The definitions of morphological characters and their associated trait states are critical for assembling a dataset that could be analysed for phylogenetic reconstruction. Here, we present coral morphological data that consist of more than a hundred characters reviewed by the Corallosphere working group. These characters would eventually form the basis of a data matrix used to reconstruct the phylogeny of all extinct and extant scleractinian families. The initial results obtained by the working group comprise poorly resolved trees, which are biased by the complexity of the multiple character states and the multiplicity of researchers involved in the coding process. When the analysis is restricted to matrices consisting of families from the Triassic and Jurassic periods and coded by a single person, resolution increased, allowing for further exploration of various ingroups and outgroups. The results presented here represent analyses of (i) a data matrix with all families represented by their type genus; (ii) a data matrix with selected families represented by their solitary or phaceloid genera; (iii) a data matrix with only Triassic corals; (iv) a data matrix with only Jurassic corals; (v) a data matrix with Triassic and Jurassic corals; and (vi) data matrices with several outgroups. Well-resolved trees have been obtained in several cases. Phylogenetic rela-tionships among basal, robust and complex groups established using molecular data are discussed in the context of the morphological phylogeny obtained here.

Amalia Notaro, ISABELLA RAFFI, DANIELE REGHELLIN

Reticulofenestra pseudoumbilicus is a Neogene calcareous nannofossil species whose highest stratigraphic occurrence (Top) is a reliable biohorizon in the Pliocene, calibrated at 3.82 Ma. The species is present in the stratigraphic record from at least the Middle Miocene, within an interval around the biohorizon Top Sphenolithus heteromorphus, calibrated at 13.53 Ma, but its lower distribution range is not precisely delineated. The study of nannofossil assemblages in sediment cores from Integrated Ocean Drilling Program IODP Site U1338 (eastern equatorial Pacific) indicates a lower stratigraphic position for the evolutionary emergence (Base) of R. pseudoumbilicus, detected in the Early Miocene with an estimated age of 16.46 Ma. This age results from a new astronomically tuned chronology, which dates the deepest sediments at Site U1338 to 16.67 Ma. Base R. pseudoumbilicus is followed above by a temporary disappearance of the taxon until a re-entrance after ~3 Myr. This lengthened stratigraphic range has been confirmed by data from other locations at low and mid-latitudes in the Atlantic. The distribution range of R. pseudoumbilicus, lasting ~13 Myr during the Neogene, is thus characterized by a variable pattern of repeated occurrences and disappearances. Comparison to benthic foraminifera δ18O and δ13C records suggests a control by global climatic/environmental conditions on these events, particularly by temperature variations. The recurrent presence of R. pseudoumbilicus at stratigraphically different intervals could represent an example of iterative evolution, expressed as repeated speciation events that are in part influenced by complex external factors related to the dynamic climate and environmental evolution during the Miocene.

Alison M Murray, Robert Holmes

Although the vast majority of fossil catfish material is isolated elements such as fin spines, a number of fossil catfishes (Siluriformes) have been named based on articulated crania from Palaeogene formations of Africa. The fossil taxa from marine sediments have been assigned to the extant marine family Ariidae, or have been assumed to have washed into marine sediments from freshwater habitats. The ability to assess the relationships of these fossils without reference to the nature of the geological sediments may provide insight into the history of these families. Most of the taxonomic work on the 11 catfish families found in Africa has focused on soft-tissues or DNA, which is problematic for the fossil material. Here we provide osteological features to distinguish families of African catfishes; eight of the families that are likely to be found in fossiliferous deposits can be distinguished based on a combination of skull features  including the morphology of the cranial fontanelle, mesethmoid, and dermal ornamentation. We reassess the familial placement of the Palaeogene catfishes. We find that †Eomacrones wilsoni, from the Palaeocene of Nigeria, belongs in Bagridae s.s. This confirms that bagrids were in Africa much earlier than the Miocene. Because this catfish comes from Palaeocene marine sediments, the biogeographic history of Bagridae needs to be reassessed to consider marine dispersal in this taxon.

Shumin Liu, Shumin Liu, Zhiheng Li et al.

Gastroliths, where preserved, can provide indirect evidence regarding diet in extinct avian and non-avian dinosaurs. Masses of gastroliths consistent with the presence of a gastric mill are preserved in many Early Cretaceous Jehol birds mostly belonging to the Ornithuromorpha. Gastroliths are also present in basal birds Sapeornis and Jeholornis in which herbivory is supported by direct evidence these taxa consumed seeds in the form of crop or stomach contents. Although gastroliths have been correlated with herbivory in non-avian dinosaurs, the presence of gastroliths and bone together in Ambopteryx calls this association in to question. Despite being known from greater numbers of specimens than other avian lineages, no unequivocal direct or indirect evidence of diet has been recovered from Jehol deposits for the Enantiornithes. A referred specimen of Bohaiornis guoi IVPP V17963 was described as preserving a small number of gastroliths interpreted as rangle, gastroliths whose function is cleaning the stomach in extant raptorial birds. However, based on comparison with gastroliths in other Jehol birds, it has alternatively been suggested that the identified structures are not ingested stones at all but some unusual mineral precipitate. Considering the limited evidence regarding diet in Enantiornithes and the importance of accurately identifying the traces in Bohaiornis in order to understand the enantiornithine digestive system, we extracted two samples of these purported gastroliths and explored these traces using computerized laminography scanning, scanning electron microscopy, energy dispersive x-ray spectroscopy, ground sections, and body size to gastral mass regressions. Similar analyses were conducted on gastroliths extracted from undisputed gastral masses of two Jehol ornithuromorphs and the non-avian pennaraptoran Caudipteryx. The combined results contradict the hypothesis that these traces are gastroliths and supports the interpretation they are mineral precipitate, most likely authigenic quartz (chalcedony). Although authigenesis is commonly responsible for the preservation of soft tissues, it is unclear if these traces record part of the tissues of this Bohaiornis. This study highlights the importance of a multidisciplinary approach in understanding unusual traces in the fossil record and reveal a previously unidentified taphonomic phenomenon in fossils from Jehol deposits.

G. Georgalis, Kazım Halaçlar, Serdar Mayda et al.

PATRICK MEISTER, SILVIA FRISIA

Upper intra- to supratidal laminites in the Norian Dolomia Principale of the Brenta Dolomites (Northern Italy) commonly consist of aphanitic and partially peloidal dolomite previously interpreted as very early diagenetic or penecontemporaneous. Re-examination of a sample prepared by focused ion beam milling through high-resolution transmission electron microscopy (TEM) revealed that dolomicrite crystals may consist of ca. 5-nm-sized nanocrystals characterized by imperfectly aligned orientation. A similar type of dolomite was found in clay-rich Carnian laminites of the Travenanzes Formation (Venetian Alps, Northern Italy) and was interpreted as indication of primary precipitation. The observation of nanocrystals in both the Dolomia Principale and the Travenanzes Formation allows hypothesizing that dolomite mud formed directly from solution via a non-classical pathway involving nucleation and aggregation of nano-particles. Domains of nanocrystalline dolomite in the Dolomia Principale are embedded within, or cemented by, calcian dolomite showing coherent lattice at the micrometre scale and a modulated structure under the TEM. This new finding provides the first evidence that one of the largest dolomite bodies occurring in the geological record, the Dolomia Principale, commenced with deposition of sediment, consisting of dolomite mud formed from solution via non-classical crystallization, and was partially affected by later pervasive diagenetic dolomitization. Based on these new observations we propose that further nano-scale studies are necessary to substantiate the hypothesis that the formation of large dolomite bodies characterized by abundant dolomicrite may have commenced by non-classical nucleation and growth processes. This approach may provide insight on non-actualistic conditions in ancient environments that may have differed, in their boundary conditions, from their modern analogues.

Xiaoming Wang, Stuart C White, Mairin Balisi et al.

Borophagine canids have long been hypothesized to be North American ecological ‘avatars’ of living hyenas in Africa and Asia, but direct fossil evidence of hyena-like bone consumption is hitherto unknown. We report rare coprolites (fossilized feces) of Borophagus parvus from the late Miocene of California and, for the first time, describe unambiguous evidence that these predatory canids ingested large amounts of bone. Surface morphology, micro-CT analyses, and contextual information reveal (1) droppings in concentrations signifying scent-marking behavior, similar to latrines used by living social carnivorans; (2) routine consumption of skeletons; (3) undissolved bones inside coprolites indicating gastrointestinal similarity to modern striped and brown hyenas; (4) B. parvus body weight of ~24 kg, reaching sizes of obligatory large-prey hunters; and (5) prey size ranging ~35–100 kg. This combination of traits suggests that bone-crushing Borophagus potentially hunted in collaborative social groups and occupied a niche no longer present in North American ecosystems.

Ya-Sheng Wu

A calcisponge fauna occurs in uppermost Permian Conodont Clarkina meishanensis yini zone of the sequence exposed in the vicinity of Laibin, Guangxi Zhuang Autonomous Region, southern China. The fauna is dominated by one thalamid species, Amblysiphonella vesiculosa de Koninck, 1863, and one new sclerosponge genus and species, Radiofibrosclera laibinensis gen. et sp. nov. They are associated with a few other accessory species, including the thalamid sponges Amblysiphonella laibinensis Deng, 1981, Colospongia sp., Polycystocoelia sp., and the inozoan sponge Acoelia discontinua sp. nov. Though the individuals are abundant, the species diversity is very low. Without common calcisponge components of Changhsingian reefal faunas, the assemblage is interpreted as not a reefal fauna. The water depth at which they dwelled was less than 105 m, and more probably less than 40 m. Its occurrence indicates a significant sea-level drop at the end of Late Permian Changhsingian Age.

Julián F. Petrulevičius

A new pentatomoid heteropteran, Chinchekoala qunita gen. et sp. nov. is described from the lower Eocene of Laguna del Hunco, Patagonia, Argentina. The new genus is mainly characterised by cephalic characters such as the mandibular plates surpassing the clypeus and touching each other in dorsal view; head wider than long; and remarkable characters related to the eyes, which are surrounded antero-laterally and posteriorly by the anteocular processes and the pronotum, as well as they extend medially more than usual in the Pentatomoidea. This is the first pentatomoid from the Ypresian of Patagonia and the second from the Eocene in the region, being the unique two fossil pentatomoids in Argentina.

M. Bylesjö, V. Segura, R. Soolanayakanahally et al.

Josefina Durango de Cabrera, Matilde N. Rodríguez de Sarmiento

The first palynomorphs recorded in the Paleogene fossiliferous beds of Laguna del Hunco Formation are described. They consist of fruiting bodies and Sporae Dispersae of Ascomycotina and Deuteromycotina fungi groups, recovered from a leaf of Laurelia guiñazui Berry (Monimiaceae) by the pull (dry peel) method. This microflora is constituted by: cf. Paramicrothallites Jain and Gupta; Callimothallus cf. pertusus Dilcher; lnapertisporites subovoideus Sheffy and Dilcher; l. circularis Sh. and D.; Monoporisporites cf. abruptus Sh. and D.; Diporisporites sp.; Multicellaesporites spp.; M. attenuatus Sh. and D.; M. Ovatus Sh. and D.; Staphlosporonites conoideus Sh. and D.; S. ovalis Sh. and D. and Staphlosporonites sp. Some of them are compared with fungi palynomorphs from neighbor areas and from North America. Bibliographic references about this subject in Argentina are also given. KEY WORDS. Argentina. Paleogene. Laguna del Hunco Formation. Fungi. Fruiting bodies. Sporae Dispersae.

Aleksandar Mezga, Blanka Cvetko Tešović, Vedrana Pretković et al.

Sixteen dinosaur footprints are exposed along the upper-bedding plane of a single Upper Hauterivian limestone layer in the Palud bay (western Istria, Croatia). This distinct footprint-bearing horizon is part of the thick Mesozoic Adriatic-Dinaridic Carbonate Platform stratal succession. Strata at the Palud site are characterized by peritidal (shallow subtidal to intertidal) limestone with several shallowing-upward cycles composed of mudstone, peloidal wackestone/packstone, peloidal packstone/grainstone and fenestral mudstone/wackestone with common geopetal infill. The Late Hauterivian age of these deposits is determined from their microfossil assemblage, which is dominated by ostracods, benthic foraminifera and calcareous green algae Dasycladales. The Palud site dinosaur footprints are circular to elliptical in shape, with no clearly visible digit impressions (except for one questionable example), and are rather large with average length of 30 cm. Most footprints have a well-defined expulsion rim that represents displacement and compression of soft, waterlogged sediment substrate by the weight of the dinosaur. All of the footprints are of nearly same shape and size, which indicates that they were produced by the same kind of tracemaker – likely a sauropod dinosaur. These animals left their footprints on top of a shallowing-upward succession of an intertidal environment during a short subaerial exposure of fine-grained carbonate sediment.

Iudin Nikita I.

The article deals with the findings of glazed ceramics produced in the South-Eastern Crimea, and then excavated at the Tsarev settlement. Their typology, chronology and topography are being introduced by the author. On the basis of the 165 analyzed fragments and whole vessels the author suggests a 4-level classification scheme, which includes the production center, functional purpose of the items, morphological characteristics and ornamentation of the vessels. Basic types and variations of vessels’ shapes are being described according to three major chronological periods: 1. Early 1300s, 2. 1330s, 3. The second half of the 14th century. Notably, the earliest findings of ceramics dated by the first two periods were located on the South-Eastern part of the Tsarev settlement. Most of all, its are the bowls on a circular underpan lacking ornamentation and covered with green transparent glazing. Since the second half of the 14th century the vessels from the South-Eastern Crimea had been widely spread on the entire area of the settlement. The assortment of vessels’ shapes used at this time along with jars and bowls, was now widened by aftobes and apothecary amphoras.

Gawlick Hans-Jürgen, Aubrecht Roman, Schlagintweit Felix et al.

The causes for the Middle to Late Jurassic tectonic processes in the Northern Calcareous Alps are still controversially discussed. There are several contrasting models for these processes, formerly designated “Jurassic gravitational tectonics”. Whereas in the Dinarides or the Western Carpathians Jurassic ophiolite obduction and a Jurassic mountain building process with nappe thrusting is widely accepted, equivalent processes are still questioned for the Eastern Alps. For the Northern Calcareous Alps, an Early Cretaceous nappe thrusting process is widely favoured instead of a Jurassic one, obviously all other Jurassic features are nearly identical in the Northern Calcareous Alps, the Western Carpathians and the Dinarides. In contrast, the Jurassic basin evolutionary processes, as best documented in the Northern Calcareous Alps, were in recent times adopted to explain the Jurassic tectonic processes in the Carpathians and Dinarides. Whereas in the Western Carpathians Neotethys oceanic material is incorporated in the mélanges and in the Dinarides huge ophiolite nappes are preserved above the Jurassic basin fills and mélanges, Jurassic ophiolites or ophiolitic remains are not clearly documented in the Northern Calcareous Alps. Here we present chrome spinel analyses of ophiolitic detritic material from Kimmeridgian allodapic limestones in the central Northern Calcareous Alps. The Kimmeridgian age is proven by the occurrence of the benthic foraminifera Protopeneroplis striata and Labyrinthina mirabilis, the dasycladalean algae Salpingoporella pygmea, and the alga incertae sedis Pseudolithocodium carpathicum. From the geochemical composition the analysed spinels are pleonastes and show a dominance of Al-chromites (Fe3+–Cr3+–Al3+ diagram). In the Mg/(Mg+ Fe2+) vs. Cr/(Cr+ Al) diagram they can be classified as type II ophiolites and in the TiO2 vs. Al2O3 diagram they plot into the SSZ peridotite field. All together this points to a harzburgite provenance of the analysed spinels as known from the Jurassic suprasubduction ophiolites well preserved in the Dinarides/Albanides. These data clearly indicate Late Jurassic erosion of obducted ophiolites before their final sealing by the Late Jurassic–earliest Cretaceous carbonate platform pattern.

James H. C. Smith, Allen Benitez