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Testing The Niche Center Hypothesis In The Fossil Record Of Atlantic Bivalves, Rhiannon Z. Nolan
Testing The Niche Center Hypothesis In The Fossil Record Of Atlantic Bivalves, Rhiannon Z. Nolan
Earth and Planetary Sciences ETDs
Paleoecological analyses of six shallow marine bivalves were conducted to test the Abundant Center Hypothesis using data from the fossil record of the Pleistocene through modern day. This hypothesis predicts the highest abundance of a species is at the center of the geographic or environmental range, decreasing toward the edges. In geographic space, distances to a centerline within a geographic range were variably correlated with population abundances, and some species displayed a sharp drop-off in abundance as distance increased. In environmental space, bivalve species showed moderate correlations between abundance and centrality when measured using cumulative data across the last 2.8 …
Assessing Ecological Relationships Among Late Triassic Vertebrates In Petrified Forest National Park, Alexandra Davis Apgar
Assessing Ecological Relationships Among Late Triassic Vertebrates In Petrified Forest National Park, Alexandra Davis Apgar
Earth and Planetary Sciences ETDs
The complex vertebrate ecosystem of the Late Triassic has not yet been fully understood, largely due to oversimplification of hypothesized trophic hierarchies and limited preservation of direct evidence of faunal interaction. Paleocommunity reconstruction attempts can also fall victim to taphonomic biases, time-averaging inaccuracies, and non-analogue paleoecologies. Utilizing a combination of PAIRS analysis and NMDS ordination, we highlight vertebrate faunal relationships within the Adamanian and Revueltian faunachrons of Petrified Forest National Park, assess the likelihood that these patterns have ecological rather than preservational drivers, and examine how these potential interactions may have been impacted by the Adamanian-Revueltian turnover event. We are …
Soil Geomorphology Of The Eastern Sevilleta Long Term Ecological Research Site, Debra Bryan-Ricketts
Soil Geomorphology Of The Eastern Sevilleta Long Term Ecological Research Site, Debra Bryan-Ricketts
Earth and Planetary Sciences ETDs
Soils in the arid to semi-arid piedmont landscapes of central New Mexico were examined in order to evaluate surficial processes and landscape evolution in the central Rio Grande Rift. These soils were found to contain key information regarding pedologic and geomorphic responses to climate change, rifting and base level drop. A rare association of sepiolite and palygorskite occurs in old soils formed in eolian fines. Pedologic and mineralogical data indicate that palygorskite formed by transformation of dust-borne, aluminum-rich minerals, and that sepiolite subsequently formed by transformation of palygorskite. The association of these two minerals, and geomorphic observations, confirm the existence …
Geochemical Characteristics And Microbial Diversity Of Co2-Rich Mound Springs Of The Tierra Amarilla Anticline, New Mexico, Brandi Cron
Earth and Planetary Sciences ETDs
This interdisciplinary research explores the water geochemistry, microbial heterogeneity, geochemical cycling, and paleohydrological longevity of a unique set of desert springs in north-central New Mexico. This series of travertine-depositing CO2-rich springs is located along the boundary zone between the Colorado Plateau and Rio Grande rift, on the southern extension of the Nacimiento fault at the Tierra Amarilla anticline (TA). Geochemical data on the spring waters show 3He/4He ratio of 0.17-0.20 RA which indicates the presence of mantle-derived helium in the groundwater. Carbon isotope values range from -4.6 to -8.1 per mil, suggesting that some of the CO2 is also deeply …