2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 108-12
Presentation Time: 11:00 AM

A NEW JURASSIC LAGERSTATTE FROM ALBERTA, CANADA, PRESERVED DURING THE TOARCIAN OCEAN ANOXIC EVENT


MARTINDALE, Rowan C.1, THEM II, Theodore R.2, GILL, Benjamin C.2 and KNOLL, Andrew H.3, (1)Jackson School of Geosciences, University of Texas at Austin, 1 University Station C1100, Austin, TX 78712, (2)Department of Geosciences, Virginia Polytechnic Institute & State University, Blacksburg, VA 24061, (3)Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138, martindale@jsg.utexas.edu

The Jurassic Period is a critical interval in the evolution of marine communities, and the Early Jurassic, in particular, contains several major environmental and ecological perturbations, namely the Triassic-Jurassic Mass Extinction and the Toarcian Ocean Anoxic Event (T-OAE). Lagerstätten deposits hold the potential to greatly expand our knowledge of evolution, community ecology, local vs. regional paleoecological changes, species distribution, and overall diversity trends during the particular portions of the geologic record they represent. Of the six Lagerstätten in the Jurassic Period (56 million years), only two are from the Early Jurassic and both occur in Europe. Here we describe a newly discovered Early Jurassic Konservat-Lagerstätte from southwestern Alberta, Canada. To date the fauna comprises shrimp and lobsters (appendages and body fossils), meter-scale articulated crinoids, articulated fish with fins and scales, semi-articulated ichthyosaurs, teuthid squid, belemnites, and a diverse suite of bivalves, brachiopods, ammonites, and microfossils. The soft-bodied preservation was found to span at least eight horizons and includes; squid organs, muscle tissue, articulated vertebrate skeletons, wood fragments, arthropod carapaces, and possibly belemnite soft-part preservation. This marine deposit is the first Jurassic Konservat-Lagerstätte from North America, and as such, will fill a considerable gap in the knowledge of global species distribution, evolution, and community structure in the Jurassic. Furthermore, the soft-tissue preservation occurs within the same stratigraphic interval as the Toarcian Ocean Anoxic Event (as defined by chemostratigraphy), making it time correlative to the Posidonia Shale Lagerstätte from Germany. For the first time in the Early Jurassic, two contemporaneous marine Lagerstätten from opposite sides of the globe can be studied. Such a circumstance is extremely rare in the fossil record, and the ability to compare both the paleontological communities and paleoenvironmental conditions between these two sites will certainly provide critical information for our understanding of both the Early Jurassic marine ecosystem and also the processes that control soft tissue preservation.