Browsing by Subject "paleoecology"

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  • Strani, Flavia; Pushkina, Diana; Bocherens, Herve; Bellucci, Luca; Sardella, Raffaele; DeMiguel, Daniel (2019)
    The intermontane Anagni Basin (Frosinone, central Italy) is an important region for Italian biochronology and paleoecology due to the presence of two rich fossil assemblages dated to the Early (Coste San Giacomo) and Middle Pleistocene (Fontana Ranuccio). These sites have yielded a vast collection of large fossil mammals with a well-documented presence of fossil equids in both localities (represented mostly by isolated teeth). Coste San Giacomo is dated to around 2.1 Ma, thereby having recorded the effects of the onset of the Quaternary glacial cycles, which led to a gradual trend toward colder and more arid conditions in the Northern Hemisphere. The fossil equids of this site belong to the first group of grazing stenonid equids of the genus Equus that spread to the Italian Peninsula during the so called "Elephant- Equus" event, which marked the appearance of new large mammals living in herds in open and arid environments. The site of Fontana Ranuccio is dated to around 400 ka, close to the MIS 12-11 succession (the "Mid-Brunhes event"), which marked the end of the Middle Pleistocene Transition. The fossil horses from Fontana Ranuccio represent one of the oldest caballoid (or "true horses") populations of the Italian Peninsula. The Anagni Basin, thus, provides important data to investigate paleoecological adaptations of these groups of equids in response to two critical environmental and climatic shifts of the Pleistocene. We explore their niche occupation by examining long-term dental wear patterns and tooth enamel carbon and oxygen stable isotopic composition. Both taxa appear to have exhibited a narrow dietary niche, displaying a clear abrasive (highly specialized) grass-rich diet. In particular, caballoid equids from Fontana Ranuccio show a more abrasion-dominated mesowear signature. Stenonid equids from Coste San Giacomo exploited broader and more diverse landscapes during the Early Pleistocene, whereas caballoid horses from Fontana Ranuccio appeared to have limited their dietary adaptations to a stricter grazing behavior in more closed environments.
  • Mäkelä, Meri (Helsingin yliopisto, 2021)
    The present retreat of the Greenland Ice Sheet will increase the amount of fjords surrounded only by land-terminating glaciers in the future. As in the Arctic, productivity is generally lower at these kinds of fjord systems than in the ones surrounded by marine-terminating glaciers, this will most likely affect the productivity and ecosystem structure of coastal marine areas. Paleorecords of past coastal ecosystems can improve our understanding of the drivers of Arctic coastal ecosystem change and provide possible future scenarios. At present, there are not many high-resolution marine ecosystem reconstructions from the Arctic near-shore areas, and in particular those, which take into account land-derived inputs are lacking. To provide a detailed reconstruction of coastal marine ecosystem change over the Holocene and study its linkages to climate and terrestrial freshwater inputs, organic-walled palynomorphs (including e.g. dinoflagellate cysts and pollen) and some basic geochemistry (including e.g. total organic carbon, C:N ratio, biogenic silica and stable isotopes of carbon and nitrogen) were examined from two radiometrically dated sediment cores from Young Sound fjord, Northeast Greenland. The results indicate that the near-shore marine ecosystem in Young Sound is clearly influenced by local forcings, such as terrestrial freshwater and organic matter inputs, during the Holocene. The results also illustrate that these terrestrial inputs affect the ecosystem structure and at least some dimension of ecosystem productivity. This study demonstrates that increasing number of fjords with only land-terminating glaciers in the future will affect marine productivity and ecosystem structure in Greenland’s fjord systems, with potential impacts on biodiversity and important fisheries. Studying past ecosystem changes in different fjord systems, and complementing marine records with proxies for terrestrial inputs, would further help constrain the future scenarios along the Greenland shore.
  • Strani, Flavia; Profico, Antonio; Manzi, Giorgio; Pushkina, Diana; Raia, Pasquale; Sardella, Raffaele; DeMiguel, Daniel (2018)
    Mastication of dietary items with different mechanical properties leaves distinctive microscopic marks on the surface of tooth enamel. The inspection of such marks (dental microwear analysis) is informative about the dietary habitus in fossil as well as in modern species. Dental microwear analysis relies on the morphology, abundance, direction, and distribution of these microscopic marks. We present a new freely available software implementation, MicroWeaR, that, compared to traditional dental microwear tools, allows more rapid, observer error free, and inexpensive quantification and classification of all the microscopic marks (also including for the first time different subtypes of scars). Classification parameters and graphical rendering of the output are fully settable by the user. MicroWeaR includes functions to (a) sample the marks, (b) classify features into categories as pits or scratches and then into their respective subcategories (large pits, coarse scratches, etc.), (c) generate an output table with summary information, and (d) obtain a visual surface-map where marks are highlighted. We provide a tutorial to reproduce the steps required to perform microwear analysis and to test tool functionalities. Then, we present two case studies to illustrate how MicroWeaR works. The first regards a Miocene great ape obtained from through environmental scanning electron microscope, and other a Pleistocene cervid acquired by a stereomicroscope.
  • Morales-Garcia, Nuria Melisa; Saila, Laura K.; Janis, Christine M. (2020)
    Savanna-like ecosystems were present at high latitudes in North America during much of the Neogene. Present-day African savannas, like the Serengeti, have been proposed to be modern analogs of these paleosavannas, particularly those from the middle Miocene of the Great Plains region of the United States. Both these extant and extinct savannas contain a preponderance of artiodactyl (even-toed ungulate) species; however, the taxonomic composition of each fauna is different. While present-day African savannas are dominated by ruminants (primarily bovids), the Neogene savannas of North America were dominated by a diversity of both camelid and non-bovid ruminant families. This study provides a quantitative test of the similarity of the artiodactyl faunas of the North American Neogene paleosavannas to those of the modern-day African savannas. A correspondence analysis of ecomorphological features revealed considerable overlap between modern and fossil faunas. The morphospace occupation of the extinct North American ruminants falls within that of the African bovids. Some of the extinct camelids also fall within this same morphospace, but many do not, perhaps indicating an environmental difference such as greater aridity in Neogene North America. The diversity and disparity of artiodactyl faunas through the Neogene of North America changed along with changing temperatures and precipitation regimes. The taxonomic and ecomorphological diversity of the Serengeti ruminant fauna is statistically comparable to those North American paleofaunas occurring during or immediately after the Middle Miocene Climatic Optimum (MMCO), but the later, more depauperate faunas are no longer comparable. This study quantitatively analyzes artiodactyl communities as they changed with the cooling and drying trend seen during the Neogene.