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Research Interests - not a comprehensive list! 

Norian (and Mesozoic, generally) Paleoecological, Taxonomic, and Environmental Dynamics

The Triassic is a fascinating period, beginning and ending with mass extinction events, and the Norian Stage of the Late Triassic represents nearly half of the entire Triassic period, ~24 million years (228-204mya)! Within this stage, several important biotic and environmental events occurred that may have had important long-term evolutionary consequences. I use macrofossil, microfossil, sedimentary, and isotopic information to evaluate these events and relate them to other important events in Earth's history and to the changing modern oceanic conditions. 


The Early Mesozoic Marine Revolution

Benthic marine invertebrates from the Norian Stage indicate that there was a dramatic ecological shift that occurred within the Norian stage among shelly prey taxa. The trends included a shift toward more mobile animals, especially those that could burrow into the sediment. This behavior may be a way for the animals to avoid predators that like to crawl along the seafloor looking for food - and in fact, the Late Triassic is precisely when many groups of predators appear in the fossil record that do exactly that! These predators include many lobsters and crabs, and also swimming predators that eat shelly animals like ammonoids, shell-crushing fish, and small marine reptiles. The prey that would be most affected by increased predation of this kind include the stationary animals that live on the surface of the sea floor - and throughout the Norian, these groups gradually declined in abundance. Determining if this trend is globally synchronous is one part of my ongoing research.


The Manicouagan bolide impact event

In the middle of the Norian stage (~214mya), an enormous rock collided with the Earth, leaving behind the second-largest crater in the last 500 million years, almost 100km in diameter. This crater is named Manicouagan, and it is located in eastern Canada. 

We do not yet understand what the effects of this massive impact were, so part of my research includes sampling Norian taxa to identify intervals of high biotic turnover and analyzing the sediments in those intervals for impact-related deposits. If an ejecta layer is found and confirmed to be from the Manicouagan crater, this will better inform scientists as to how large impacts perturb environments and cause faunal changes. If Manicouagan did not cause any faunal change, this is still excellent information about important impact parameters that may determine the environmental effect a large impact might have, by comparing the effects of Manicouagan to the Chicxulub impact event that caused a mass extinction. There are some important differences between these impact events, and a faunal comparison will highlight the importance of particular features, depending on if the biotic effects were similar or not.


Norian-Rhaetian Boundary Events and the End-Triassic Mass Extinction

This boundary interval is not well-understood on a global scale, and defining the Norian-Rhaetian boundary biostratigraphically, isotopically, and in terms of biotic turnover will better inform us in understanding the spatial and temporal events of the devastating End-Triassic mass extinction that began in the short Rhaetian stage. Using strontium isotope chemostratigraphy and a dramatic excursion consistent with an increase in tectonic spreading rates, I correlated sedimentary sections from Europe to west-central Nevada (Tackett et al, 2014). Across this sedimentary interval is a rapid proliferation of silicic sponge microfossils that may be related to the onset of volcanism in the Late Triassic. 

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