483 research outputs found
Basal Primatomorpha colonized Ellesmere Island (Arctic Canada) during the hyperthermal conditions of the early Eocene climatic optimum
Anthropogenically induced warming is transforming Arctic ecosystems across a geologically short timescale, but earlier episodes of Earth history provide insights on the nature and limitations of biotic change in a rapidly warming Arctic. Late early Eocene strata (~52 Ma) of the Margaret Formation on Ellesmere Island, Nunavut, Canada sample a warm temperate ecosystem with a polar light regime situated at ~77°N paleolatitude. This extinct boreal ecosystem hosted a diversity of early Cenozoic vertebrates, including thermophilic taxa such as crocodilians and tapiroid perissodactyls. Here we describe two new species of the early primatomorphan Ignacius from Ellesmere, which are by far the northernmost known records for Paleogene Primatomorpha. Ellesmere species of Ignacius are sister taxa, indicating a single colonization of Ellesmere from farther south in North America coincident with the onset of the hyperthermal Early Eocene Climatic Optimum (EECO). The Ellesmere Ignacius clade differs from closely related taxa inhabiting mid-latitudes in being larger (thereby conforming to Bergmann’s rule) and having modified dentition and muscles of mastication for a dietary regime emphasizing hard objects, possibly reflecting an increased reliance on fallback foods during long polar winters. The late early Eocene mammalian fauna of Ellesmere indicates that its unique paleoenvironment rendered it uninhabitable to some clades, including euprimates, while selected taxa were able to adapt to its challenging conditions and diversify
Tarsal morphology of the pleuraspidotheriid mammal Hilalia from the middle Eocene of Turkey
Pleuraspidotheriids are a group of primitive ungulate mammals that, until recently, were thought to be restricted to the late Paleocene of Western Europe. It has been hypothesized that this family actually survived in Central Anatolia until at least the middle Eocene. However, these anachronistically young Anatolian “survivors”, including the genus Hilalia, were previously documented mainly by dental remains. Here, we describe the previously unknown astragalus of Hilalia saribeya, which confirms the pleuraspidotheriid affinities of the genus, and supports phylogenetic reconstructions that place Hilalia as the sister group of Pleuraspidotherium. The morphology of the astragalus suggests sub-cursorial plantigrade locomotion for H. saribeya, although its tarsal morphology remains generalized enough that scansorial capabilities cannot be ruled out. The evolution of Hilalia is addressed in the context of the apparent geographic isolation of Central Anatolia during the Eocene. The endemic character of the mammalian fauna of Central Anatolia during the middle Eocene emphasizes how the complex paleogeography of the northern margin of Neotethys impacted local biotas in a region situated at the crossroads of very distinctive biogeographic zones
An Analysis of Spatio-Temporal Landscape Patterns for Protected Areas in Northern New England: 1099-2010
Context: Landscape ecology theory provides insight about how large assemblages of protected areas (PAs) should be configured to protect biodiversity. We adapted these theories to evaluate whether the emergence of decentralized land protection in a largely private landscape followed the principles of reserve design. Objectives: Our objectives were to determine: (1) Are there distinct clusters of PAs in time and space? (2) Are PAs becoming more spatially clustered through time? and (3) Does the resulting PA portfolio have traits characteristic of ideal reserve design? Methods: We developed an historical dataset of the PAs enacted since 1900 in the northern New England region of the US. We conducted spatio-temporal clustering, landscape pattern, and aggregation analyses at both the landscape scale and for specific classes of land ownership, conservation method, and degree of protection. Results: We found the frequency of PAs increased through time, and that area-weighted clusters of PAs were heavily influenced by a few recent large PAs. PA clustering around preexisting PAs was driven primarily by establishment of large PAs focused on natural resource management, rather than strict reserves. Since 1990, the complete portfolio has increased in aggregation, but reserve patches have become less aggregated and smaller, while patches that allow extractive uses have become more aggregated and larger. Conclusions: Our extension of landscape ecology theory to a diverse portfolio of PAs underscores the importance of prioritizing conservation choices in the context of existing PAs, and elucidates the landscape scale effects of individual actions within a portfolio of protected areas
An Analysis of Spatio-Temporal Landscape Patterns for Protected Areas in Northern New England: 1099-2010
Context: Landscape ecology theory provides insight about how large assemblages of protected areas (PAs) should be configured to protect biodiversity. We adapted these theories to evaluate whether the emergence of decentralized land protection in a largely private landscape followed the principles of reserve design. Objectives: Our objectives were to determine: (1) Are there distinct clusters of PAs in time and space? (2) Are PAs becoming more spatially clustered through time? and (3) Does the resulting PA portfolio have traits characteristic of ideal reserve design? Methods: We developed an historical dataset of the PAs enacted since 1900 in the northern New England region of the US. We conducted spatio-temporal clustering, landscape pattern, and aggregation analyses at both the landscape scale and for specific classes of land ownership, conservation method, and degree of protection. Results: We found the frequency of PAs increased through time, and that area-weighted clusters of PAs were heavily influenced by a few recent large PAs. PA clustering around preexisting PAs was driven primarily by establishment of large PAs focused on natural resource management, rather than strict reserves. Since 1990, the complete portfolio has increased in aggregation, but reserve patches have become less aggregated and smaller, while patches that allow extractive uses have become more aggregated and larger. Conclusions: Our extension of landscape ecology theory to a diverse portfolio of PAs underscores the importance of prioritizing conservation choices in the context of existing PAs, and elucidates the landscape scale effects of individual actions within a portfolio of protected areas
Tarsal morphology of the pleuraspidotheriid mammal Hilalia from the middle Eocene of Turkey
Pleuraspidotheriids are a group of primitive ungulate mammals that, until recently, were thought to be restricted to the late Paleocene of Western Europe. It has been hypothesized that this family actually survived in Central Anatolia until at least the middle Eocene. However, these anachronistically young Anatolian “survivors”, including the genus Hilalia, were previously documented mainly by dental remains. Here, we describe the previously unknown astragalus of Hilalia saribeya, which confirms the pleuraspidotheriid affinities of the genus, and supports phylogenetic reconstructions that place Hilalia as the sister group of Pleuraspidotherium. The morphology of the astragalus suggests sub-cursorial plantigrade locomotion for H. saribeya, although its tarsal morphology remains generalized enough that scansorial capabilities cannot be ruled out. The evolution of Hilalia is addressed in the context of the apparent geographic isolation of Central Anatolia during the Eocene. The endemic character of the mammalian fauna of Central Anatolia during the middle Eocene emphasizes how the complex paleogeography of the northern margin of Neotethys impacted local biotas in a region situated at the crossroads of very distinctive biogeographic zones
Eocene metatherians from Anatolia illuminate the assembly of an island fauna during Deep Time
Island biotas have disproportionately influenced the history and development of evolutionary
biology, but understanding their genesis and evolution across geological timescales has
been hindered by a poor fossil record. Here we augment the insular Eocene (~43 Ma) mammalian
fauna known from the Pontide terrane of central Anatolia by describing two new
metatherian taxa (stem marsupials) from the Lu¨ lu¨k Member of the Uzunc¸arşıdere Formation
in the Orhaniye Basin. Geological and paleontological data indicate that the Pontide terrane
was an island on the northern margin of Neotethys during the middle Eocene. Reflecting its
geodynamic context in a region of active tectonic convergence, the Eocene Pontide terrane
hosted a unique combination of Laurasian and Gondwanan mammals, including an anachronistic
radiation of pleuraspidotheriids (archaic ungulates) that went extinct on the European
mainland ~13 Ma earlier. Most of the mammalian clades occupying the Pontide terrane colonized
it by dispersal across marine barriers rather than being stranded there through vicariance.
Endemic radiations of pleuraspidotheriid ungulates and polydolopimorphian
metatherians on the Pontide terrane reveal that in situ diversification was an important factor
contributing to faunal assembly and evolution. The insular fauna that arose on the Pontide
terrane is highly analogous to that of modern Sulawesi, which evolved under strikingly similar
geological conditions. Illustrating the ephemeral nature of insular biotas across macroevolutionary
timescales, the demise of the Pontide fauna coincided with paleogeographic changes
enabling more cosmopolitan taxa to reach it for the first time. The high level of endemism
shown by the mammalian fauna of the Uzunc¸arşıdere Formation eliminates the Pontide terrane
as a potential early Eocene dispersal corridor between western Europe and India.INSU-2011 CT49215-12W296-13EAR- 154368
A Quantitative Evaluation of the Galaxy Component of COSMOS and APM Catalogs
We have carried out an independent quantitative evaluation of the galaxy
component of the "COSMOS/UKST Southern Sky Object Catalogue" (SSC) and the
"APM/UKST J Catalogue" (APM). Using CCD observations our results corroborate
the accuracy of the photometry of both catalogs, which have an overall
dispersion of about 0.2 mag in the range 17 <= b_J <= 21.5. The SSC presents
externally calibrated galaxy magnitudes that follow a linear relation, while
the APM instrumental magnitudes of galaxies, only internally calibrated by the
use of stellar profiles, require second-order corrections. The completeness of
both catalogs in a general field falls rapidly fainter than b_J = 20.0, being
slightly better for APM. The 90% completeness level of the SSC is reached
between b_J = 19.5 and 20.0, while for APM this happens between b_J = 20.5 and
21.0. Both SSC and APM are found to be less complete in a galaxy cluster field.
Galaxies misclassified as stars in the SSC receive an incorrect magnitude
because the stellar ones take saturation into account besides using a different
calibration curve. In both cases, the misclassified galaxies show a large
diversity of colors that range from typical colors of early-types to those of
blue star-forming galaxies. A possible explanation for this effect is that it
results from the combination of low sampling resolutions with properties of the
image classifier for objects with characteristic sizes close to the
instrumental resolution. We find that the overall contamination by stars
misclassified as galaxies is < 5% to b_J = 20.5, as originally estimated for
both catalogs. Although our results come from small areas of the sky, they are
extracted from two different plates and are based on the comparison with two
independent datasets.Comment: 14 pages of text and tables, 8 figures; to be published in the
Astronomical Journal; for a single postscript version file see
ftp://danw.on.br/outgoing/caretta/caretta.p
The Malcolm Boat (38CH803): Discovery, Stabilization, Excavation, and Preservation of an Historic Sea Going Small Craft in the Ashley River, Charleston County, South Carolina
The following report details the results of an investigation of the remains of a small historic sailing craft, The Malcolm Boat (38CH803), discovered in a mud bank of the Ashley River in 1985. The investigation, conducted in June of 1992, with partial funding support from the South Carolina Department of Archives and History, revealed that the vessel was a small ocean-going hull dating to the last quarter of the eighteenth century and the first quarter of the nineteenth. The analysis presented discusses the vessel\u27s age, method of construction and function as a coastal or possibly inter-islander trader, and places the vessel within a regional maritime historical context. Historical context is provided in the form of the background history of shipbuilding in South Carolina and a preliminary typology of local small craft. Methods of site stabilization for intertidal zone sites are discussed with recommendations for future work in this new area of investigation in the state.https://scholarcommons.sc.edu/archanth_books/1194/thumbnail.jp
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