Hasil untuk "Paleontology"

Conrad Schmidt, Tara Beuzen-Waller, Dana Pietsch et al.

The Early Bronze Age in southeastern Arabia is characterized by a significant shift in the archaeological record that coincides with the regional deterioration of climatic conditions associated with the end of the Holocene Humid Period. This study presents evidence for human modification of the local landscape around Building VII, a large circular structure at Al-Khashbah, Oman dating to the late third millennium BC. Through multiproxy analyses combining archaeological, geophysical, geomorphological, pedological and malacological, geochemical, palynological, and archaeobotanical datasets, we found evidence for the excavation of sediments at the foot of Building VII during the Umm an-Nar period. This excavation was subsequently filled by sediment presenting evidence for soil development, increased organic carbon, salt enrichment, microcharcoal, and snails. We suggest that both the excavation and subsequent aggradation may be related to gardening activities, though archaeobotanical and palynological analyses did not yield sufficient preserved material for local vegetation reconstruction. Nevertheless, our results contribute valuable insights into local human-environmental interactions and show that investigations beyond the visible archaeology of the monumental buildings of Early Bronze Age Oman can record a wide range of human activities and land modification near these important sites. These results have the potential to provide information on the resilience and adaptation to climate aridification by Umm an-Nar period peoples in central Oman and landscape modification during this period of economic transformation, increasing sedentarization, and growing social differentiation.

Rut Mayo de la Iglesia, Farid Saleh, Jonathan B. Antcliffe et al.

Summary: Algae are a major constituent of modern and ancient ecosystems. Investigating their evolutionary history relies on understanding their past morphologies as preserved in the fossil record. This is challenged by postmortem decay of algal cells before stabilizing as fossils. Yet, no work has documented the decay of algae in sediments under controlled experimental conditions and applied this information to interpretations of the fossil record. Here, 120 green algal samples belonging to three different morphogroups, and 40 red cyanobacteria samples were left to decay while buried in kaolinite for nine weeks. Multispectral macroimaging revealed that external morphologies were preserved long after death. Nevertheless, chemical compounds decayed over time, and pigments, such as phycoerythrin and chlorophyll became almost undetectable. Some algal morphogroups showed cell compressions, or taphonomic artifacts, which could resemble structures previously described as organelles in fossils, potentially challenging some interpretations in early eukaryotes.

Yann Lelièvre, Quentin Jossart, Quentin Jossart et al.

Coastal ecosystems of sub-Antarctic islands are threatened by increasing climate-driven changes and direct anthropogenic pressures. Significant effects on marine communities are expected, but benthic ecosystems of these isolated islands remain largely under-explored. Effective preservation of these nearshore environments requires deeper ecological assessments and comprehensive biodiversity knowledge. In this regard, this study reports findings from a survey carried out in 2021 at two sites – Baie du Marin and Crique du Sphinx – located on the eastern coast of Ile de la Possession (sub-Antarctic Crozet archipelago, Southern Ocean). We investigated the composition and structure of nearshore benthic faunal communities using a quantitative fieldwork protocol and an integrative molecular- and morphology-based taxonomic approach. A total of 124 morphotypes were identified, including a high proportion (72%) of rare species. Both sites exhibited similar benthic invertebrate communities. Structurally complex habitats such as hard substrates or areas dominated by macroalgae exhibited higher species richness and diversity. The investigated benthic invertebrate communities are typical of the sub-Antarctic area but featured unique structures, including dense tube-dwelling polychaete colonies. This study will provide a baseline for future monitoring programs and for the preservation of sub-Antarctic coastal benthic ecosystems.

Maria Gisela Lefebvre, Diego Alejandro Sampietro, Alejandro Fabian Zucol et al.

El presente trabajo de investigación tiene como objetivo la utilización de los fitolitos como proxy para realizar la reconstrucción paleoambiental de la sección media del valle de Santa María (Tucumán - Argentina) durante el Holoceno superior. Además, considerar esto en el contexto paleoambiental regional y global. Para ello, se tomaron muestras de sedimento extraídas en perfiles ubicados en diferentes localidades: Molle Yaco, Yasyamayo y El Pichao. Las asociaciones fitolíticas encontradas muestran la existencia de secciones y subsecciones en las que se divide cada uno de los perfiles. Estas reflejan la presencia de condiciones húmedas y frías desde momentos previos a la era cristiana hasta aproximadamente 1.000 AP cuando las mismas se tornan áridas y cálidas, contemporáneamente a la Anomalía Cálida Medieval, para luego retomar los episodios templados y fríos correlacionables a la Pequeña Edad del Hielo. Las condiciones ambientales actuales están representadas por asociaciones fitolíticas que describen una vegetación árida y semiárida.

Alan W. Zdinak, Steven J. Jabo

Juan Manuel Robledo, DANIEL BARASOAIN, SOFÍA I. QUIÑONES et al.

The sedimentological characteristics and fossil vertebrates studies are notoriously increasing in the earth sciences field, as a way to infer reliable information about the biota and the paleoenvironmental and paleoclimatic context. In this framework, we establish relationships among the flora, fauna and the depositional environment during the Late Miocene in Northwestern Argentina. The sedimentology features are described in detail from sediments collected in the Quebrada Salta section, and the Xenarthra Cingulata Kraglievichia paranensis (Pampatheriidae) and Cranithlastus xibiensis (Glyptodontidae) are recorded for the first time in the Palo Pintado Formation (Salta Province, Argentina). The sedimentary observations support the presence of a sinuous sandy-gravel fluvial system with swamps and lacustrine, under a wet tropical climate. In this environment, the vertebrates here described would have inhabited open zones close to these freshwater bodies, predominated by xeric vegetation, mainly represented by grasses and sedges with scarce arboreous elements.

Vitaly Dernov

New finds of well-preserved remains of coiled nautiloids from lower Moscovian sediments (Kamenskaya Formation) of the Donets Basin (eastern Ukraine) allowed to describe the color pattern on the conch surface of species of the genera Parametacoceras, Metacoceras, Coelogasteroceras and Ephippioceras. The conch color pattern of the studied nautiloids is represented by longitudinal light bands along the ventrolateral shoulder (Parametacoceras and Metacoceras), transverse thin lines on the venter (Ephippioceras), and a black spot on the body chamber (Coelogasteroceras). Described color patterns represent disruptive coloration. Environmental conditions, e.g. slow sedimentation, absence of agents of mechanical and chemical destruction, dysaerobic conditions and rapid burial were obviously the most important factors for the preservation of coloration on the studied conchs of coiled nautiloids.

Daniel Edgardo Udrizar Sauthier, Daniela de Tommaso, Pablo Teta

Se da a conocer la conformación de los ensambles de micromamíferos no voladores para cinco secuencias paleontológicas del Holoceno ubicadas en la cuenca del río Chubut. Con la información obtenida se propone una hipótesis ambiental para los últimos miles de años en Patagonia central. Se realizaron 13 dataciones radiocarbónicas con métodos convencionales. Entre las cinco secuencias se contabilizaron 12.644 individuos (MNI). En conjunto, se registraron al menos 18 taxones de micromamíferos. El estudio de los yacimientos nos permitió inferir que desde los 5,5 ka hasta los 4,0 ka se encontraban en la región ambientes de estepa patagónica. A partir de los 4,0 ka, especialmente en el valle inferior del río Chubut, empieza a notarse la influencia del Monte, alternando condiciones frías y húmedas con más cálidas y secas como las actuales. Los micromamíferos sugieren la existencia de dos tendencias principales durante los últimos 5,0 ka. Para buena parte del segmento temporal, se mantiene la estructura taxonómica (cuantitativa y cualitativa) con cambios sutiles en las abundancias de algunas especies. Hacia los últimos 0,15 ka se hace evidente una modificación más profunda de los ensambles, signada tanto por desapariciones locales como por incrementos o decrementos marcados de algunas especies. Las evidencias disponibles indican a las actividades antrópicas como las principales responsables de estos cambios.

Keith Berry, Ganesh K. Jaganathan

Paleobotanists debate whether the Cretaceous/Paleogene boundary (KPB) event was selective. As the hypothesis that the KPB event selected for plants with fast-return leaf economic traits (e.g. deciduousness) has lost empirical support in recent investigations, researchers have turned to alternative hypotheses to explain an abrupt decline in primary productivity across the KPB. Two contemporary hypotheses designed to explain selectivity among plants across the KPB are that (1) polyploids exhibited greater survivorship than their diploid progenitors or counterparts (i.e. the KPB-whole genome duplication or WGD hypothesis) and that (2) plants with desiccation-tolerant (DT), i.e. orthodox, seeds exhibited greater survivorship than plants with desiccationsensitive (DS), also known as recalcitrant, seeds. Late embryogenesis abundant (LEA) protein gene families are perceived to confer DT and seed longevity among vascular plants. Non-parametric Wilcoxon signed-rank test for matched pairs and a Mann-Whitney U test reveal that plant lineages perceived to have undergone WGD across the KPB exhibit significantly greater numbers of LEA genes than those that did not. On the basis of these data, this investigation elicits a merger between the KPB-WGD and KPB-seed traits concepts. However, emphasis is shifted from the concept of WGD as an immediate adaptation to climatic stress at the KPB (the KPB-WGD hypothesis) to the concept that WGD was an exaptation, which, by definition, fortuitously enhanced the survival of vascular plants across the KPB but that probably evolved initially in other climatic contexts.

Brice B. Hanberry

Climate classification allows an efficient encapsulation of climate data into climate units. For North America and most of Central America during 20, 14, 13, 11, 10, 7, 5, and 1 thousand years ago (ka) and recent years, I applied a Köppen-Trewartha classification system, but with dry classes subsumed under primary thermal classes to preserve information. The boreal and polar classes decreased from a combined 70% of area during 20 ka until reaching 42% of area at 7 ka, after which the area remained relatively stable. Conversely, the subtropical and temperate classes increased from 25% of area until reaching 53% of area at 7 ka, with slight increase of the tropical class. The combined dry subclasses increased from 7.5% to 15% of area, primarily in the subtropical and temperate classes, displaying unique trends over time. Based on ordination, the classes since 5 ka are similar; the 1950 interval is most similar to 1 and 5 ka and the intervals of 1600 and 1800 are most similar. The climate classes and transitions generally corresponded with major vegetation distributions. Visually, political boundaries appeared to parallel climate classes, which might indicate the influence of long-standing ecological differences on human land use and settlement. A future research need is identifying the influence of climate on directing settlement and political boundary establishment.

Yizhi Xu, Shunxing Jiang, Xiaolin Wang

The Istiodactylidae is a group of pterodactyloids characterised by large nasoantorbital fenestrae and labiolingually compressed teeth, with several records reported from the Early Cretaceous of northeastern China and western Europe. Here we report a new istiodactylid, Lingyuanopterus camposi gen. et sp. nov. from the Jiufotang Formation of Lingyuan, Liaoning, northeastern China. The holotype is represented by a near-complete skull, mandible and atlas-axis complex. It is distinguished from other istiodactylids by several characters, including two autapomorphies: short triangular tooth crowns with sharp mesial and distal carinae limited to the distal teeth, mandibular symphysis occupying approximately a quarter the mandible length. We also report the presence of helical jaw joints in istiodactylids, and provide a revised diagnosis of the clade Istiodactylidae, which includes five genera: Istiodactylus, Liaoxipterus, Nurhachius, Luchibang and Lingyuanopterus. Four pellets containing fish fragments were observed and are tentatively interpreted as bromalites of Lingyuanopterus. Although members of this clade possess similar skull morphologies, istiodactylids vary in terms of their dentition, with at least three forms from the Jiufotang Formation alone. This may represent different feeding strategies, and also indicate a similarity between the pterosaur assemblages of northeastern China and Britain during the Early Cretaceous.

Galimova Madina Sh. , Berezin Alexander Yu. , Berezina Natalia S. et al.

The paper features the results of archaeological and paleontological research in the left bank of the Kuibyshev reservoir, at the mouth of the Aktai River (Republic of Tatarstan). Bones and teeth of fossil mammals (223 finds) were collected under the cliff of the reservoir for 300 m. The following species were identified: mammoth, woolly rhinoceros, bison, tur, horse, reindeer, elk, fox, marmot etc., which may belong to the Upper Pleistocene or Khazar faunal complexes. Also the bones of the limb of a large horse were collected, which were identified as a horse of Mosbach of the middle Neo-Pleistocene Singil’ faunal complex existed in the Volga region about 400 thousand years ago. Upper incisor of a giant beaver and the large jaws of a Pleistocene wild boar were also found at the Comintern site and were probably attribute to Singil’ fauna. At the same time, the authors collected 39 artifacts from flint and one from quartzite, belonging to the Ust’-Kamaskaya culture of the terminal Paleolithic. Of particular importance were two localities fixed by the authors in stratified sections – flint flake and rhinoceros limb bone, which lay within the buried soil formed during the warming period of the Middle Valdai (MIS-3).

Amane Tajika, Naoki Morimoto, Neil H. Landman

Abstract Assessing the taxonomic importance of the suture line in shelled cephalopods is a key to better understanding the diversity of this group in Earth history. Because fossils are subject to taphonomic artifacts, an in-depth knowledge of well-preserved modern organisms is needed as an important reference. Here, we examine the suture line morphology of all known species of the modern cephalopods Nautilus and Allonautilus. We applied computed tomography and geometric morphometrics to quantify the suture line morphology as well as the conch geometry and septal spacing. Results reveal that the suture line and conch geometry are useful in distinguishing species, while septal spacing is less useful. We also constructed cluster trees to illustrate the similarity among species. The tree based on conch geometry in middle ontogeny is nearly congruent with those previously reconstructed based on molecular data. In addition, different geographical populations of the same species of Nautilus separate out in this tree. This suggests that genetically distinct (i.e., geographically isolated) populations of Nautilus can also be distinguished using conch geometry. Our results are applicable to closely related fossil cephalopods (nautilids), but may not apply to more distantly related forms (ammonoids).

Hans-Dieter Sues

MARIA ALEKSANDRA BITNER

Twenty species of Recent brachiopods belonging to the genera Neoancistrocrania, Basiliola, Basiliolella, Dyscolia, Abyssothyris, Xenobrochus, Terebratulina, Fallax, Septicollarina, Frenulina, Amphithyris, Annuloplatidia, Leptothyrella, Dallina, Campages, Thecidellina and Minutella have been identified in the material collected during the French cruise Bordau 2 to the Tonga Islands, South-West Pacific. Apart from Frenulina sanguinolenta all species represent the first records for the Tonga Islands. The investigated brachiopod fauna shows the greatest affinity to that from Fiji and New Caledonia, having 16 and 12 species in common, respectively. Although less affinity is observed with the New Zealand fauna, there are two species, Terebratulina australis and Amphithyris buckmani reported so far only from New Zealand, Fiji and Tonga. The biodiversity of brachiopods inTonga is similar to that inFiji but half as great as that inNew Caledonia andNew Zealand regions and much higher than inFrench Polynesia.

Luciana Witovisk, Luciana Barbosa Carvalho, Andrea Fernandes Costa et al.

The Girls education course “Girls with science: Geology, Paleontology and Gender” hosted by Museu Nacional/UFRJ were conceived by the idea that children and youth education in science should be focus on awake girls interest in science, once in the actual initiatives the masculine participation is more frequent. The highest number of subscription in extended education courses show how the society is interested in activities of continues education focus on gender identity. The course main objective is present to girls how science is developed by ordinary people and even in research areas where the male gender is predominant the women participation is growing. This article aims spread the work method used in the “Girls with science” course composed of theoretical and practical activities using day by day examples in Geology and Paleontology. Also, we expect encourage other institution in create, reproduce and development new activities for general audience. The work team is composed of professors, technical personal, undergraduate and postgraduate students in several different areas and is the one of the project highlights, once students have the chance of observed and see female scientist in careers different phases. The results show is necessary more interaction between highacademic education and school. Also, the focus on everyday activities that can improve the understanding of science is welcome. Recently, the brand new course was award with the honorable mention in the 8º Ibero Americano award in Museum Education, andnow is part of the good habits database in education sustained by Ibermuseus.

Francisco J. Goin, Adriana M. Candela

Quirogalestes alniagaucha n. gen. et sp. is an early Eocene Pichipilinae (Paucituberculata, Caenolestidae) distinguished from Pichipilus and Phonocdromus by the larger size of its p3, and by having a lower molar pattern that is primitive with respect to those of Pichipilus and Phonocdromus. The protoconid is less reduced, the anterobasal cingulum is moderately developed, and the paraconid and metaconid are only slightly separated. The holotype, and only known specimen, was recovered from middle levels of Casamayor Fm. (Casamayoran Age; early Eocene) at Cerrito Fructuoso, in Valle Hermoso (Chubut Province, Argentina). It represents the oldest and more generalized pichipiline known to date. The middle Eocene Hondonadia feruglioi n. gen. et sp. (?Polydolopimorphia) resernbles several polydolopimorphians in the size of its upper canine, the length and width of the incisive vacuities, an upper molar pattern characterized by a well-developed "hypocone" (displaced metaconule), and a (moderate) twinning of the paracone and metacone with stylar cusps B and D, respectively. The holotype, and only known specimen, comes from middle Eocene (Mustersan Age) levels at Gran Hondonada (= "Pozón Grande"; Sarmiento Group), near Paso de Indios (Tehuelches Department, Chubut Province, Argentina). It may represent the persistence (into well-advanced Paleogene times) of a relatively generalized polydolopimorphian quadritubercular molar pattern, which was already established in southern South America by the middle Paleocene. KEY WORDS. Marsupialia. Paucituberculata. Polydolopimorphia. Systematics. Eocene. Patagonia.

Daniel G. Poire, Analía Del Valle

Cambrian/Ordovician trace fossil assemblages from the Balcarce Formation are described. In the Cabo Corrientes outcrops at the Atlantic coast, four sedimentary facies are distinguished as follows: a) Pebble Sandstone Facies with progradation surfaces and no evidence of bioturbation; b) Crossbedded Sandstone Facies in tabular and lenticular sand bodies with rare Palaeophycns isp.; c) Heterolithic Facies with wavy bedding bearing Daedalus labeckei, Herradurichnus scagliai, Rusophycus isp., Scolicia isp., and Teichichnus isp.; and d) Sandy Heterolithic Facies with Herradurichnus scagliai and Scolicia isp. This sedimentary succession is considered here as interbar, bar margin, and central bar facies in a subtidal environment on an open marine shelf. Ethologically, two principal trace fossil assemblages are recognised. Both assemblages are closely associated with sedimentary facies and  specific colonising events may be distinguished. The first assemblage consists of Rusophycus isp. and Herradurichnus scagliai, which occur as furrows on the substrate at the water-sediment interface. The second one is composed of Daedalus labeckei, Scolicia isp. and Teichichnus isp., which are post-depositional burrows developed a few centimeters below the sediment surface by sediment feeding organisms. From this study, the palaeoenvironmental history of the bioturbation of this shelf bar deposit can be summarised. Firstly synsedimentary ichnofossils developed in interbar and bar margin heterolithic deposits. Secondly, these deposits were buried by vertical accretion of migrating sand waves, and then mud feeding organisms started working below the sediment surface living on the available nutrients in the wavy bedded heterolithic facies. Simultaneously, in the overlying new interbar and bar margin facies similar syndepositational traces were developed. KEY WORDS. Trace Fossils. Sedimentary Facies. Shallow Marine Deposits. Cambrian-Ordovician. Balcarce Formation. Tandilia. Argentina.

Kenneth L. Finger, Alfonso Encinas, Sven N. Nielsen