Taxonomic Affinity of Ediacaran Acritarchs:
Acritarchs, closed organic walled microfossils, have historically been considered phytoplankton because of their small size, their environmental placement, and their similarity to Phanerozoic forms such as prasinophyte algae and dinoflagellates. These affinities, however, do not necessarily form the most parsimonious categorization of acritarchs, especially the diverse taxa found in Ediacaran rocks. In terms of pure morphological similarity, many Ediacaran acritarchs bear closer resemblance to the diapause egg cases of modern invertebrate groups, 
especially those of certain arthropods. I use Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) to analyze the ultrastructure of fossil and modern forms in order to resolve the issue of Ediacaran acritarch taxonomic affinity. Comparison of both morphology and ultrastructure between modern analogs and a diversity of acritarch taxa reveals further similarity between some groups of Ediacaran acritarchs and modern metazoan cysts. Placement of some Ediacaran acritarchs within the Metazoa requires reinterpretation of the acritarch record and invites ecological and environmental hypotheses regarding the presence of recalcitrant cysts in Ediacaran seas.
Read more about this project here and here.
Enigmatic Mineralized Scale microfossils from the Tindir Formation, Yukon Territory:
I am actively involved in a reinvestigation of enigmatic protistan mineralized scales found in Neoproterozoic rocks of the Tindir Formation of the Yukon Territories and Alaska. These fossils, first described systematically by Alison and Hilgert (1981), are unique to the Tindir formation. In June 2007, I and colleague Francis Macdonald returned to the original site and re-collected many of the chert beds originally sho
wn to be fossiliferous. Our results indicate that the unit from which the fossils originate is 150-250 million years older than previously suggested. Our analysis of the fossils is ongoing. Subsequent re-sampling of the Tindir Formation in June of 2008 resulted in hundreds of additional chert samples from both the original locality and importantly, from new sections laterally distributed within a few kilometers of the original site. We expect that these new samples will shed light on the temporal and spatial distribution of these unique fossils as well as provide us with a greater sense for their biodiversity. I am collaborating with Nicholas Butterfield at Cambridge University and Bill Schopf at UCLA on the morphology, composition, and taxonomic affinity of the Tindir scale fossils.
Macroscopic tubular fossils from the Ediacaran Nama group, Namibia:
In June 2006, I participated in the Agouron Advanced Field Course investigating the terminal Ediacaran and early Cambrian of Namibia. As part of this collaborative project, I have headed up work on abundant macroscopic tubular fossils found in terminal Neorproterozoic shales of the Nama Formation.
sideWalk Through Time
I helped to organize a Harvard community public art/science project on September 29th, 2009, in
collaboration with the Harvard Museum of Natural History and local street artist Sidewalk Sam. Details and photos of the event can be seen here. We created a 200 meter timeline of the Phanerozoic on the sidewalks outside the HMNH and illustrated it with chalk drawings of animals and plants from each time period. We also brought out specimens from Harvard's teaching collection and had graduate students and staff on hand to answer questions and talk about the fossil record. Students from all over the University participated and created amazing works of (temporary) art.