Invertebrate Paleontology at Smith College

Research

Brief Biography:

My career in geology began as an undergraduate at the University of Rochester. My interest in field-based research led me to the laboratory of Dr. Dave Bottjer at the University of Southern California where I began studying the aftermath of the end-Permian mass extinction event. I was also fortunate to work on other exciting topics while at USC like enigmatic Neoproterozoic carbonates with Dr. Frank Corsetti. After completing my Ph.D in 2004, I came to Harvard University as an Agouron Institute Post-doctoral Fellow to work with Dr. Andy Knoll and other members of the Knoll group. I remain interested in the end-Permian extinction event but the focus of my postdoctoral research was on Middle Cambrian-Lower Ordovician strata of the western United States and western Newfoundland. In addition to working with Andy, I have also collaborated with Matt Hurtgen and Seth Finnegan on these projects. Recently, I have started a research project with Tanja Bosak, Francis Macdonald, and Paul Hoffman on the Rasthof Formation of northern Namibia. The Rasthof Formation is an unusual carbonate succession deposited directly atop glacial deposits thought to be Sturtian in age.

Research Interests:

Cambro-Ordovician carbonates

My current research on Cambro-Ordovician carbonates addresses the evolution of the carbonate system, specifically the biological and chemical interplay of the oceans, during Middle Cambrian-Middle Ordovician time. The abundance of microbialites and other unusual carbonates during these ~40 million years has garnered much interest because this interval encompasses the time period that follows the "Cambrian Explosion" of complex body plans yet precedes the Ordovician radiation of crown group organisms. Understanding the geochemical, sedimentological, and biological factors that influenced Earth systems early in the Paleozoic will ideally shed light on the nexus of conditions that led to the evolution of robust skeletonized organisms in the Ordovician.

"Snowball Earth" interests

Recent field work in northern Namibia focused on the Rasthof Formation. This laterally-extensive carbonate unit was deposited above a possible Sturian-aged glacial unit. The Rasthof Formation is enigmatic because it contains abundant "roll-up" structures that may be related to cohesive microbial mats. This project will attempt to elucidate the influences on carbonate deposition and the small- and large-scale environmental changes recorded in the Rasthof Formation.

Modern carbonate environments

My recent work in modern carbonate settings in the Bahamas has focused on quantifying predation rates in mollusc assemblages and determining the depositional conditions of unusual eolian sedimentary structures. The predation work involves quantifying drilling frequencies at various locations on San Salvador Island and Cat Island, Bahamas, to determine what affects predations rates in tropical carbonate settings. A study of the taphonomy of shells reveals that taphonomic differences exist between beaches that represent broadly similar depositional environments. Future work will focus on linking the new data we generate on modern carbonate environments with the sedimentary record.

End-Permian mass extinction and recovery

I am interested in the interactions between organisms and the environments in which they live viewed through the scope of deep time. My dissertation work focused on trying to understand the recovery of marine ecosystems following the end-Permian mass extinction, the most devastating extinction in the history of life. To this end, I studied the unusual sedimentary rock record of the Early Triassic as a way of gauging how sediments reflect both the ecological and environmental changes that occurred during and after the mass extinction. Recent work with collaborators focuses on understanding the geochemical and redox evolution of Permo-Triassic oceans as a way of understanding both the extinction event itself as well as the prolonged recovery that occurred during the Early Triassic.

I am also interested in the interval that records the recovery of the marine fauna. I am currently investigating Middle Triassic carbonates preserved in Italy and Switzerland to track the increase in skeletal abundance and to see how the radiation of organisms in the Middle Triassic leaves its mark on the sedimentary record.

Current Student Research Projects

Quantifying skeletal abundance in the Ediacaran Nama Group, S. Namibia, Alexandra (Sasha) Breus '10

See Sasha in action

Skeletons in archaeocyathid bioherms of the Lower Cambrian Forteau Formation, Hannah Clemente '11

See Hannah in action

Geochemistry of the Upper Cambrian-Middle Ordovician Cow Head Group, Katie Castagno '12

See Katie in action

Predation on a modern carbonate tidal flat, Cat Island, Bahamas, Sarah Motti '10

See Sarah in action

Benthic communities of the Middle Triassic Angolo Limestone, northern Italy, Siobhan Duffey, '10

Past Student Research Projects

A synthesis of predation on San Salvador Island, Bahamas, Siobhan Duffey, '10

Carbon isotope stratigraphy of the Lower Ordovician St. George Group, Newfoundland, Emily Bush '11

The rise of skeletons in the Ordovician; a field-based approach, Alexandra (Sasha) Breus '10

Comparative analysis of boreholes in modern molluscs on San Salvador Island, Bahamas, Marquela Stevenson, '09

Carbon isotope statigraphy and metazoan abundance, Middle Triassic Angolo Limestone, Mai Houa Vue '12

Origin of roll-up structures in a Sturtian cap carbonate, Namibia, Katie Castagno '12

Environments and carbon isotope composition of roll-up structures in a Sturtian cap carbonate, Namibia, Marie McLane, '08

Tracking the Cambro-Ordovician radiation of skeletons, Danielle Schmandt '09

Field Photos

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