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A new paper by Malcolm Hodgskiss detailing the carbon isotope chemostratigraphy of the Paleoproterozoic Labrador Trough has been published in the Canadian Journal of Earth Sciences. Malcolm, along with colleagues at McGill University, had to battle epic insects, structure, and lack of exposure, but ultimately prevailed with a new view of the Lomagundi-Jatuli excursion in this region. 

The Ordovician-Silurian extinction was the first major mass extinction of the Phanerozoic, yet its cause(s) remain debated. A new paper by Richard Stockey, published in Nature Communications, demonstrates that oceans spanning the Ordovician-Silurian boundary and through the first several million years of the Silurian had extensive regions that were anoxic and sulfidic, and that these low-oxygen oceans correlate with lower diversity in the fossil record. The paper used a novel Monte Carlo framework to better account for uncertainty in metal isotope mass balance models. 

A new paper by lab members Dan Mills and Erik Sperling has been published in Geobiology. This paper stemmed from the 'Point-Counterpoint' format debate at the Banff Geobiology Conference in 2017 between Sperling, Mills and Chris Reinhard, and the ideas from this discussion were then fleshed out in collaboration with Devon Cole, Doug Erwin, Noah Planavsky and Susannah Porter in a group discussion at the Santa Fe Institute.

Seven members from the Historical Geobiology Lab headed to San Diego for the Ocean Sciences conference. This was a great opportunity to learn about current research in oceanography and present our results to the modern oceanography crowd!

Posted 2/20/20

Iron speciation is one of our most robust proxies to understand the redox conditions of ancient water columns. This paper by Slotznick et al. (with lab members Erik Sperling and Austin Miller, as well as other collaborators at UC Berkeley, University of Utrecht, and University of Oxford) used magnetic techniques and XRD to probe the specificity of extractions used in iron speciation. The analyses confirmed the specificity of many of the extractions but revealed that the oxalate extraction mainly targets iron-rich clays such as berthierine and chamosite.

The lab welcomes Dr. Murray Duncan (Phd: Rhodes University) to work on a project funded by the Stanford Woods Institute. The project, in collaboration with Dr. Fio Micheli and Dr. Chris Lowe at Stanford's Hopkins Marine Station, explores using the Metabolic Index to predict the future habitable range of abalone and urchins in the NE Pacific ocean. Murray's research website can be found here: https://miduncan.wixsite.com/research

 Posted 1/16/2020

Six members of the Historical Geobiology Lab traveled to Bozeman, MT, for the 27th Annual Stanford Project on Deepwater Depositional Systems (SPODDS) meeting and field workshop. The meeting started with a day-long shale geochemistry short course led by Erik Sperling, followed by a field trip to the Devonian-Carboniferous Sappington Formation, a day-long technical review by SPODDS students, and a field trip to the Mesoproterozoic LaHood Formation in beautiful Jefferson Canyon. 

Posted 9/21/2019

Much of the fieldwork by the Historical Geobiology Lab is done in Yukon and Northwest Territories, but this summer the lab took a break from big hills and Backpacker's Pantry to primarily work at west coast marine stations. The goal for this work was to conduct respirometry measurements on invertebrate groups represented in the fossils record (brachiopods, crinoids, bivalves, gastropods, sea urchins, etc.).

Lab member Malcolm Hodgskiss has published a paper in PNAS titled "A productivity collapse to end Earth’s Great Oxidation." The work focused on rocks of the Belcher Group, from his main thesis area in the Belcher Islands, Hudson Bay, Nunavut, Canada. The Belcher Group was recently dated by Malcolm to ~2018 Ma, in the direct aftermath of the Great Oxidation Event.

Malcolm Hodgskiss has published a paper in Earth and Planetary Science Letters on his research on the Belcher Group, in the Belcher Islands, Nunavut, Canada. These strata cover the Orosirian Period (2050 to 1800 Ma) and include the first unambiguous cyanobacterial fossils. In this paper, Malcolm incorporated 13C carbonate carbon isotope chemostratigraphy and high-precision U-Pb geochronology to place the first constraints on these fossil and the Orosirian carbon cycle. The paper can be accessed here:

Congratulations to Hailey Deres for winning the Miller-Marsden Prize for Innovative Research on the Environment at Stanford's School of Earth Science graduation ceremony. Hailey's undergraduate thesis focused on how temperature, oxygen, and body size interact to limit the aerobic habitable range of red abalone in the California Current ecosystem. 

Congratulations to the Historical Geobiology lab members who have received external and internal grants this spring!

In collaboration with an expert on reproducibility in the Stanford School of Medicine, we have published a perspective on study-level reproducibility in geobiology. The paper is intended for early career scientists or those less familiar with the literature on statistics and reproducibility, and uses examples from psychology, ecology, and medicine to encourage practices that will promote reproducible science within our field. The paper, published in Geobiology, can be accessed here.

Graduate student Tom Boag, in collaboration with lab members Richard Stockey and Erik Sperling and colleagues at Yale University, has published a new paper proposing an ecophysiological basis for the deep-marine origin of Ediacaran organisms. Paleontologists have long questioned why these organisms appeared when and where they did: in the deep ocean, where light and food are scarce, in a time when oxygen in Earth's atmosphere was in particularly short supply.

In collaboration with Stanford colleague Jon Payne and University of Washinton colleagues Curtis Deutsch and Justin Penn, Erik Sperling published a new paper in the journal Science investigating the causes of the Permian-Triassic mass extinction. The paper uses a physiological model (the Metabolic Index) to explore how the synergistic effects of warming and marine oxygen depletion could have driven the extinction.

In collaboration with colleagues at the University of California, Berkeley, we have published a paper in PNAS that uses detailed investigations of iron mineralogy and rock magnetics to understand redox conditions in the 1.1 billion year old Paleolake Nonesuch. These approaches offer a novel alternative to understanding deep-time redox geochemistry, especially in situations such as ancient lakes where techniques such as iron speciation do not have appropriate modern calibrations. The paper by Slotznick et al.

Historical Geobiology lab members recently attended the 26th annual SPODDS (Stanford Program on Deepwater Depositional Systems) workshop and field conference in the Ventura, CA area. Students were able to visit and learn about outcrops of the Miocene Monterey Formation, perhaps the type unit for using oceanographic principles to understand the stratigraphic record, and Cretaceous turbiditic fore-arc fill of the Great Valley Group.

In collaboration with colleagues at the University of California, Riverside and MIT, we have recently published a paper on a new sterane biomarker, 26-methylstigmastane, or 26-mes. The sterol precursors of this biomarker are only found in modern demosponges, and the presence of this biomarker in Cryogenian-age strata provide an independent line of evidence for the presence of Neoproterozoic demosponges. The paper can be found here: https://www.nature.com/articles/s41559-018-0676-2

Posted 10/15/2018

The Historical Geobiology Lab recently finished up a successful field season working on Ediacaran successions in the Canadian Cordillera. In particular, we were happy to have several students from our SPODDS consortium (Stanford Program on Deep Sea Depositional Systems) out to help us better constrain depositional environments. In July, Tom Boag continued to investigate the paleontology and stratigraphy of the Rackla Group in the Wernecke Mountains of Yukon alongside Erik Sperling, Jared Gooley, and collaborators Justin Strauss and James Busch from Dartmouth College.

Erik Sperling and Rich Stockey published a review paper on the Cambrian 'explosion' in Integrative and Comparative Biology. In considering possible environmental triggers of the Cambrian radiation, the paper explores the metaphor of the 'fire triangle'--changes to food supply and temperature could have been equally important as oft-considered oxygen changes.

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