Invertebrate Paleontology Staff & Associates


Jocelyn A. Sessa, PhD

Assistant Curator of Invertebrate Paleontology
Assistant Professor, Department of Biodiversity, Earth & Environmental Science


Jocelyn Sessa is a paleobiologist who uses the fossil record as a natural laboratory to study times of change in earth’s history. Her research melds fossil and modern data to elucidate the response of mollusk faunas (clams and snails) to environmental perturbations across space and time. Sessa’s studies span a wide range of events, from the mass extinction that killed off the dinosaurs to past climatic fluctuations, including intervals of past and present global warming. By analyzing the chemistry of mollusk shells, she also reconstructs the climatic conditions that affected ecosystems.

Sessa’s hunt for mollusks is a worldwide endeavor, with fieldwork along the US eastern seaboard, the US Gulf Coast, California, Romania and Angola. An important facet of her scholarship is mentoring high school through graduate students in research projects. Sessa is passionate about making science accessible to everyone. Since 2007, she has participated in programs to engage groups under-represented in the sciences, and she is excited to continue this work in the Philadelphia Area.

For more details about Jocelyn’s work, please check out:


Katy Estes-Smargiassi

Collections Manager of Invertebrate Paleontology


Katy is responsible for the daily care and maintenance of the approximately 1 million specimens in the ANSP Invertebrate Paleontology collection. Her taxonomic expertise is in Neogene and Quaternary mollusks, and she is particularly interested in Pleistocene scaphopod communities of the Eastern Pacific. Her work in museums has primarily focused on large-scale digitization efforts in invertebrate paleontology collections, and she is excited to continue this work at the Academy in a collection that has never been shared online before. Katy is also passionate about student mentorship and increasing diversity in the geoscience workforce. Prior to joining the Academy of Natural Sciences team, she worked at the Natural History Museum of Los Angeles County and the Florida Museum of Natural History. 

Please contact Katy with any questions about the ANSP IP collections.


Rosie Oakes, PhD

Postdoctoral Researcher


Rosie is a geologist and oceanographer interested in how changes in ocean chemistry impact marine biota. Rosie’s Ph.D. research spanned the Cretaceous (~ 93 million years ago) to the modern. Her work in the Cretaceous was focused on how changes in volcanism impacted calcareous plankton at the Cenomanian – Turonian Boundary. In the modern, she’s interested in how ocean acidification, caused by increased carbon dioxide from the atmosphere dissolving in the ocean, is affecting a group of tiny swimming snails called pteropods. Rosie’s work has developed a method to quantify the thickness of these organisms using micro-CT scanning, and since then she’s spent over 200 hours scanning shells! During her time at the Academy, Rosie intends to use specimens from museum collections to understand how pteropods have been impacted by ocean acidification over the last 150 years.

Beyond the lab, Rosie believes that it’s important to share her research with the world. In addition to travelling to international science conferences and publishing papers, she makes time to attend school science fairs and participate in outreach events at the Academy of Natural Sciences of Drexel University in a hope to inspire the next generation of scientists.

For more details about Rosie’s work, check out her website:


Wunn Noon Naw

Undergraduate work-study student, Curatorial Assistant

Wunn is a freshman majoring in Environmental Science at Drexel University. She hopes her work in the Invertebrate Paleontology collection will help guide her academic path and help make her education more interdisciplinary. Wunn is excited about the hands-on experience she gets working with a large collection of specimens and wants to learn more about the different invertebrates in the collection. In her free time, she likes to volunteer, paint, and explore different restaurants in Philadelphia.


Erin Wright

Co-op student, Curatorial Assistant

Erin Wright is a sophomore environmental studies and sustainability major who is also pursuing a public health minor. She is currently on co-op in Invertebrate Paleontology, and she also works part time in Diatoms. After graduation, she sees herself working in environmental policy or compliance law.


Alexis Wiley

Co-op student, Curatorial Assistant

Alexis is a pre-junior biological sciences major concentrating in evolution, ecology and genomics. She plans on studying evolutionary biology for conservation in her future. Currently, she enjoys learning about the biodiversity represented in the fossil record through the invertebrate paleontology collection.

Alexis studied abroad in Bioko through the Drexel in Equatorial Guinea program this previous winter. In her free time, she volunteers with Students Run Philly Style mentoring high school students through running.


Kelly Rozanitis

Undergraduate Student Researcher

Kelly is a senior Geoscience major at Drexel University with concentrations in Paleontology and Applied Geology. Her interests include the chemistry and structure of fossils, as well as curating and caring for the collections. She has experience curating and preparing vertebrate fossils and looks forward to improving her skillset with invertebrate fossils as well. Outside of school and the Academy, she enjoy cooking and hiking with her dog.


Alexandra Buczek

Doctoral Candidate in Comparative Biology, Richard Gilder Graduate School at the American Museum of Natural History

Advised by Melanie J. Hopkins and Jocelyn A. Sessa

Alexandra is a geologist and paleobiologist primarily interested in the influence of climate change on nearshore marine ecosystems. Alexandra’s PhD research focuses the response of Southern Californian coastal marine mollusk communities to climate change during the Plio-Pleistocene period (5.3 – 1.5 million years ago), during which the Earth experienced major warming followed by a drastic cooling into the Pleistocene glacial periods. Her multidisciplinary research brings together isotope stratigraphy, paleoecological statistical analyses, and stable isotopic data in order to determine the main changes in mollusk communities during a period of major climate change as well as deduce the environmental drivers behind those observed changes. 

For more details about her work, please don't hesitate to contact Alexandra through email.

 bryce at grand canyon

Bryce Koester

Graduate Student, Department of Biodiversity, Earth & Environmental Science

Bryce is a first year graduate student at Drexel University with a background in paleontology. Her research interests are centered around marine invertebrates, such as mollusks and foraminifera, and their responses to anthropogenic stressors. During her time as an undergraduate, Bryce researched the effects of heavy metal pollution on the mutation frequencies of foraminifera. At the Academy, Bryce will investigate the direct and indirect impacts of ocean acidification on modern pteropods, a critical organism in marine communities. Bryce is passionate about increasing the accessibility of environmental science to policy decision makers and the public and is looking forward to participating in outreach through the Academy of Natural Sciences of Drexel University.

 scientist at microscope

Andrew J. Fraass, PhD

Research Associate in Invertebrate Paleontology

As a micropalaeontologist and palaeoceanographer, Andy Fraass works to understand how past examples of climate change and evolution interact. He does this using a tiny group of single celled marine zooplankton called planktic foraminifera.

Fraass is currently working to understanding the role of biology in the carbonate cycle. The oceans currently absorb an outsized amount of carbon dioxide. Planktic foraminifera produce carbonate (CaCO3) shells. Those shells make up a substantial amount of the carbonate on the seafloor. This carbonate acts like a buffer, helping to stabilize the ocean’s chemistry. Those shells are also the world’s best fossil record, one good enough we can examine how species evolve, not genera or families like we usually need to use. We know that when these plankton go extinct there’s a change in the amount of carbonate deposited. Using a new database with >50 years of scientific ocean drilling data, Andy works to understand what the key risks are to plankton during several past examples of climate change and how those key risks are expressed in the deposition of carbonate.

Fraass is a Research Associate with the Academy, but he can normally be found at the University of Bristol where he is a Vice Chancellor’s Fellow in Earth Sciences.

For more more details about Andy’s work, please check out: