Effects of the Central Atlantic Magmatic event on climate, ecosystems, and evolution at high versus low latitudes:

This NSF-funded project aims to understand the end Triassic extinction (ETE – 201 Million years ago), one of five mass extinctions in Earth’s history. This extinction has been correlated to massive volcanic eruptions (Central Atlantic Magmatic Province) during the breakup of Pangea emitted large amounts of greenhouse gases, which in turn caused massive habitat-change.  Late Triassic plants and animals could not cope. As a result, many animal and plant species went extinct, allowing for new animals to thrive, notably dinosaurs. We will focus on two field locations: the Moenave Formation of Utah, near the sub-tropics during the time of extinction, and the Elliot Formation of South Africa and Lesotho, near the South Pole. The geographical separation of these locations will help us understand the effect of latitude on extinction in two very different settings. We will refine estimates of the ages of these two formations and collect climate data from rocks and fossils, including temperature, CO2 concentration, and mean annual precipitation.  We will place these measurements into a refined timescale of climate proxy data.  By combining our timescale with the occurrence of fossils, we will predict how major climatic changes cause extinction, thus providing us with clues about how to mitigate the current increased levels of species extinctions. This project is in collaboration with researchers from the Utah Geological Survey, St. George Dinosaur Track Museum, University of Cape Town, University of Witwatersrand, Ohio University, University of Connecticut, University of Texas at San Antonio, and Boise State University

Linking Geological and Climate History of North America to the Cretaceous Terrestrial Revolution

The Early to Late Cretaceous transition is marked by profound faunal and floral reorganization that dramatically altered the terrestrial ecosystem, as part of the Cretaceous Terrestrial Revolution (KTR, Lloyd et al., 2008). This biotic revolution occurred within a backdrop of significant geologic (mountain building and seaway incursion) and climatic (increased CO2 concentration and global warming) changes. Because of its size, latitudinal span, and relatively complete rock sequence, the North American Western Interior Basin (WIB) is uniquely well suited to studying the KTR. This study aims to document these biotic, geologic, and climatic changes and to investigate their interrelationships by 1) developing a refined chronostratigraphic framework for key WIB rock units, 2) collecting paleoclimatic proxy data from rocks and fossils to compare regional climate and biotic change, 3) increasing cross-formational biodiversity comparisons by targeting temporal and regional gaps in the fossil record, and 4) using quantitative analyses to deconstruct the pace and timing of biotic evolution and compare key evolutionary events to the physiographic/ climatic history of the region.

Vertebrate Fauna of the Lower Cretaceous Strata from Southwest Arkansas

In the late 1980’s an assemblage of vertebrate material was discovered at the Briar Site Gypsum Mine, the site of extensive sauropod and theropod tracks from the overlying De Queen Limestone outside of Dierks, Arkansas. The assemblage was discovered in the Holly Creek Formation, an organic-rich, pyrite-bearing dark grey mudstone. Within the assemblage, a diverse fauna of micro and macrovertebrates were discovered. We provide a preliminary description of the assemblage. Combined, the macrovertebrate and microvertebrate assemblage represents faunas identified from the Trinity Group of Texas and the Antlers Formation of Oklahoma and Texas, but also contains taxa identified from Laramidia (Clover and Cedar Mountain formations) and Appalachia (Arundel Formation). A description and understanding of the age of this assemblage is important for understanding paleobiogeography as well as the timing of the incursion of the Western Interior Seaway. The seaway that split North America into two continents, Laramidia and Appalachia. Future and current work is to characterize the isotopic composition of the entire fauna to understand the ecosystem, niche partitioning, and global meteoric groundwater isotopic composition to compare to other sites globally.