WELCOME        RESEARCH        PUBLICATIONS        PROSPECTIVE STUDENTS

I have interests in many aspects of marine paleoecology, including community change during mass extinctions or intervals of major environmental change and the general relationship between biodiversity and relative abundance and ecosystem functioning. Some of my current research projects are outlined below, but I have a number of other potential topics for interested students. A complete list of my publications can be viewed here.


Marine Paleoecology During Late Paleozoic Climate Change 
 
Climate change often has a profound effect on the biosphere. My research has documented large-scale shifts in the composition of shallow marine communities in eastern Australia during the transition from the Early Permian icehouse to the Middle Permian greenhouse. This work has also shown that cold-adapted taxa of the glacial biota displayed quite disparate responses to climate warming. Future work will focus on Artinskian communities, integrating paleoecological data with paleotemperature proxies to determine if rapid climate fluctuations contributed to disruption of marine ecosystems.
Bivalves in diamictite
Bivalves Eurydesma and Deltopecten among glacial dropstones, Sakmarian, Maria Island (Tasmania)



Permian brachiopods
Silicified Late Permian (Wuchiapingian) brachiopods
from the Episkopi Formation, Hydra, Greece

Permian Extinction Events
 
My research on Late Permian extinctions has primarily concentrated on the earlier end-Guadalupian event, at the end of the Middle Permian. My data from silicified collections indicate that major changes in the abundance of the Paleozoic and Modern faunas predated the end-Permian extinction event, implying that the extinction was part of a prolonged environmental crisis. I have also been constructing a large database of Permian marine invertebrate fossil occurrences, which I have used to re-assess the severity and cause of the earlier end-Guadalupian crisis. My ongoing work seeks to understand the relationship between upwelling of euxinic water and the catastrophic deterioration of Permian ecosystems. 



Decoupling of Diversity and Abundance
 
One of the least understood aspects of paleoecology is the relationship between taxonomic richness and relative abundance. In general, there appears to be good correspondence between diversity and abundance at longer temporal scales and at higher taxonomic levels. Several instances of decoupling (where richness and abundance are not correlated) have been recognized, but its prevalence and causes remain a mystery. My work has documented decoupling of global diversity and local abundance of brachiopods and molluscs in the Late Permian; future work will attempt to unravel the causes of that decoupling. I have also worked in conjunction with other members of the University of Southern California Paleobiology group to reconstruct long-term trends in abundance in the Phanerozoic.

Decoupling
Diversity and relative abundance of brachiopods, bivalves, and gastropods in the Middle and Late Permian