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Taphonomic analyses have been conducted on the macromammal remains found in Sedimentary Unit 7 of the lower Pleistocene Pirro 10 site of the Pirro Nord locality in Italy. Recent field research has concentrated on investigating the fossil content of this site and the genesis of the karst network and its related deposits. In the present study, we distinguish between preburial and synsedimentary (during burial) processes in order to group the vertebrate remains into different taphonomic categories according to their various states of preservation, thus introducing the concept of taphorecord—borrowed from invertebrate taphonomy—into macrovertebrate taphonomy for the first time. Element quantification, evaluation of transport effects, and state of preservation of the skeletal elements were studied and all elements separated into four taphorecords according to their relative chronology. The use of taphorecords also improves the accuracy of the data obtained from the various methods of element quantification. The analysis of bone sorting and orientation indicates that the fossiliferous deposits originated by water flows carrying both fossils and sediments, alternating with phases of carcass accumulation and reelaboration of bones from previously deposited layers. The study presented here serves as a proof of concept for the use of taphorecords in analyses of fossiliferous deposits in caves.
The Upper Ordovician Effna, Botetourt, and Liberty Hall limestones of Virginia record deposition in several paleoenvironments along a carbonate ramp during the early history of the Taconic Foreland Basin. Four distinct lithofacies are present, i.e., biohermal mudstone and wackestone, biostromal grainstone, nodular deep-flank limestone and shale, and basinal mudstones and shale, and each of these is associated with different trilobite biofacies. Cluster analysis and ordination define biofacies, and characterize gradients and patterns within the trilobite relative abundance data. Biofacies are clearly delineated along a depth gradient, with gradational compositional changes between associations. The moderate-diversity bioherm biofacies is dominated by illaenids (Illaenus, Bumastoides) and cheirurids (Sphaerexochus). The high-diversity biostromal biofacies is also an illaenid-cheirurid association, but is proportionally enriched in cheirurids, and includes off-bank elements not common in the bioherm. The high-diversity deep-flank facies is associated with an Ampyx-Isotelus-Nileus assemblage that gradationally replaces the biostromal biofacies. The deep flank gives way to a low-diversity Isotelus-Calyptaulax-Raymondaspis association of cosmopolitan trilobites in the outer slope and basin environment. These biofacies characterize local environments in the Taconic Foreland Basin just prior to, and in the initial phases of tectonically driven oceanographic change that led to regional extirpation of the buildup fauna and the reorganization of deep-water trilobite biofacies. New associations of taxa not found elsewhere in Laurentia are common within the foreland basin, suggesting that the archetypal biofacies described here are reorganized with the onset of regional environmental change.
The water vapor conductance (GH2O) of the neosauropod eggs from the Lower Cretaceous Sanagasta nesting site in La Rioja Province, Argentina, was examined and compared with other Cretaceous Argentinean oological material. The 2900 mgH2O/day·Torr GH2O of the Sanagasta eggshells confirms an extremely moist nesting environment and supports field observations of dug-out nests in a geothermal setting. The observed thinning of the outer eggshell surface during incubation increases gas conductance and concomitantly decreases eggshell mechanical resistance during the late ontogenetic stages, thus facilitating embryonic development and hatching. The Sanagasta and Entre Ríos Province faveoloolithid eggs display the highest and comparable GH2O values and share several morphological and diagenetic characters, indicating comparable nesting strategy in geothermal settings. However, the faveoloolithid Yaminué and La Pampa Province specimens cluster together with lower GH2O values closer to the megaloolithid eggs. The GH2O of the megaloolithid egg Megaloolithus patagonicus was reconsidered and new results are now congruent with other reported megaloolithid GH2O values. Additionally, we hypothesize that Y-shaped pore canals of M. patagonicus, which upper sections reach only the top third or half eggshell thickness and, a wider section in the middle would not compromise the overall egg mechanical resistance like vertical pores connecting directly the outer to the inner eggshell surfaces. Such pore spatial arrangement and geometry would enhance, as the eggshell thins during incubation, a greater GH2O, GO2 and GCO2 and facilitate embryonic development in high moisture nesting contents. Overall, data suggests that neosauropod nesting and brooding behaviors were dependent on elevated moisture nesting environments.
Dark, pelagic sediments of the uppermost Cenomanian Bonarelli Level (OAE2 event) interval, in two classical sections Contessa and Bottaccione in the Central Apennines, contain unbioturbated and bioturbated beds suggesting fluctuations in pore water oxygenation from anoxic to oxic or dysoxic conditions. The oxic and dysoxic improvement events prior to, during, and after the event are marked by biogenic structures showing an increase in the diversity of the trace fossils (Chondrites, Planolites, Thalassinoides, Trichichnus, and Zoophycos) from none to five ichnotaxa in individual beds. The number of anoxic events differs in the Contessa and Bottaccione sections, even though they are only 2.5 km apart. Comparison with sections from the Carpathians (Poland) and the Betic Cordillera (Spain), reveals that minor anoxic events below and above the Bonarelli Level are absent in the studied Apennine sections. Moreover, the diversity and density of trace fossils in the Apennine sections are lower than those from other studied sections in the Tethys, most likely indicating a comparatively lower availability of food in the Gubbio area as a result of its paleogeographic location. The preservation of trace fossils, controlled by the consistency of sediments and diagenetic processes, can mask diversity and density in some beds.
Herein we provide the first report of the diversity of fungi and fungus-like organisms within a Mesozoic hot spring ecosystem. The Jurassic San Agustín hot spring deposit (Patagonia, Argentina), represents only the second known Phanerozoic hot spring ecosystem with an associated microflora and contains diverse, exceptionally preserved microorganisms. Preserved propagules include flask-shaped pycnidia produced by extant coelomycetes, shield-like and nearly round thyriothecia of extant Microthyriales in the ascomycetes, variously shaped spore-like bodies representing chytrid and chytrid-like zoosporangia and other life cycle forms, and additional fungal and fungus-like remains (spores, hyphal fragments, reproductive structures) of uncertain affinity. Many of these microorganisms are associated with variously decayed organic remains, most commonly of horsetails. This expands the fungal fossil record and provides a unique opportunity to learn about the biology of Mesozoic microorganisms.
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