Current Research
Small Title
Figure: Penn et al., 2018, depicting their model of temperature-dependent hypoxia as a driver of the end-Permian marine mass extinction.
In the past 0.5 billion years or so, several cataclysmic events, known as mass extinction events, have swept through the globe and nearly wiped out life itself. With the exception of outlying mass extinctions such as the one triggered by an asteroid impact, most of these events were predominantly triggered by volcanic eruptions that choked the atmosphere and oceans with massive amounts of carbon and sulfur. In turn, the ocean became more acidic, global oceanic temperatures skyrocketed, and oxygen levels depleted, all resulting in a huge toll in biodiversity.
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Rifling through the record of life to see how ecosystems have responded to changing environments can help us to better predict how modern marine ecosystems will fare as a result of the current biodiversity crisis. ​​
I took this image of an ancient home just outside Riyadh city in Saudi Arabia
My research is two-fold:
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A large part of it involves combining data from geochemistry ( which tells us about oceanic oxygen and temperature); paleontology (which tells us about which animals lived at a particular time, and where); and physiology (which tells us about how well animals can withstand changes in oceanic temperature and oxygen) to provide a mechanistic model that explains why marine ecosystems became so simple in their diversity, and so globally interconnected, after key intervals in deep time.
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The other portion of my research involves taxonomically identifying the fossils of mollusks (i.e. snails and clams) which my collaborators and I have collected in central Saudi Arabia, and which represent what marine communities might have been like following the wake of the most devastating mass extinction known as the end-Permian mass extinction.
![Selectivity of mass extinctions-4[88].png](https://static.wixstatic.com/media/f339c1_145bb3e0c0774a4989ee75fac966a306~mv2.png/v1/crop/x_0,y_0,w_2239,h_2250/fill/w_471,h_476,al_c,q_85,usm_0.66_1.00_0.01,enc_avif,quality_auto/Selectivity%20of%20mass%20extinctions-4%5B88%5D.png)
I drew this graphical abstract for a paper I coauthored to explain how we examine patterns in past extinction events (and the recovery of ecosystems afterwards) with processes related to organismal physiology and changes in oceanic temeperature and oxygen. Much of the work I do involves investigating potential links of biogeographic recovery patterns of benthic marine ecosystems to these physiological concepts.
My work mainly involves marine invertebrate fossils, namely mollusks such as clams and snails. These fossils are globally widespread and have a rich stratigraphic record, which means their fossil record spans much of the 542 million year history of visible life.
Along with biogeographic and paleo-ecological analyses, I am training to taxonomically identify bivalves (ex: clams), gastropods (ex: snails) and brachiopods from my study area and period. These are not my study specimens, but I snapped a pic of these lovely fossil bivalves during a field trip with our interns in Capitola beach, CA. These fossils are 5 million years old!
My father, a retired professor who specializes in stratigraphy, worked on the stratigraphy of the same site I am sampling my fossils from (40 years ago!) and lent his expertise in the area and collaborated with us on one of my projects in Saudi!
