The Search for Early Fossil Sharks in Lower Devonian rocks of the Mackenzie Mountains, NWT
Principal Investigator: Wilson, Mark V.H. (1)
Licence Number: 15224
Organization: University of Alberta
Licenced Year(s): 2013 1998 1996 1990
Issued: Mar 25, 2013
Project Team: Dr. Todd D. Cook, Ph.D. (Postdoctoral Fellow, University of Alberta), Ms. Stephanie A. Blais, B.Sc. (Ph.D. Candidate, University of Alberta), Ms. Lindsay A. Mackenzie, M.Sc. (Ph.D. Candidate, University of Montana), Mr. L. Allan Lindoe (Field Technician, University of Alberta)

Objective(s): To recover some of the oldest-known body fossils of sharks and their relatives as well as other associated fossils; and to take reference samples of rocks from measured stratigraphic sections at the fossil site, making field records of variation of rock types and fossil content of rock layers.

Project Description: The 2 objectives of this research project are:
1) to recover some of the oldest-known body fossils of sharks and their relatives as well as other associated fossils. The anatomy of the fossil species will be described in detail and published in international journals. These fossils will allow identification of fragments of related species found at other sites worldwide, and will allow the research team to test the main competing ideas about the origins of teeth in sharks and other vertebrate animals; and 2) to take reference samples of rocks from measured stratigraphic sections at the fossil site, making field records of variation of rock types and fossil content of rock layers. The research team will submit the rock samples to stable-isotope geochemical analysis to identify any major global geochemical or extinction events (there is a major event recognized elsewhere in the world at about the same time as the deposition of the MOTH rock layers). The stable-isotope records will allow the research team to improve interpretation of the ancient marine environment in which the animals lived, and also potentially to improve dating of the rocks using patterns of rise or fall of isotope ratios.

On site, the research team will search for and collect fossil vertebrate specimens that are almost always found on pieces of scree or talus, having fallen from the outcrop at some time in the past and having been naturally weathered. No significant excavations will be undertaken to find or collect fossils.

The research team will carefully document and label the discovered and collected fossils and take reference samples of rocks from measured sections, recording the rock types and the fossil content of each rock sample. Each fossil or rock sample will be labeled with location and measured height in the section. GPS coordinates and geo-tagged photos of the localities and rock layers will also be taken.

Laboratory work will involve dissolving the carbonate cement within the fossil-bearing rock with dilute, buffered acetic acid. Slabs will be rinsed weekly, dried, and exposed fossil parts will be protected from acid damage by coating them. The slabs will then be returned to the dilute acid and the cycle repeated.

The sediment residues from acid treatment will be examined for microfossils, which will be concentrated by passing the residues through a series of sieves of graduated mesh sizes. Any tiny fossil specimens will be recovered ("picked") from the residues with fine art brushes. Drawings will be made using a digital tablet. Images of rock and tissue thin sections will be made with compound microscopes and images of microfossils will be made by Scanning Electron Microscope (SEM). Larger specimens such as complete skeletons will be coated with ammonium chloride sublimate to enhance contrast and then digitally photographed. Internal and external 3D reconstructions will be obtained from micro-CT scans using Osirix software. Figures for publication will be prepared using graphical computer software.

Routine elemental analysis of rock and fossil samples during SEM study will be by EDX (energy-dispersive X-ray spectroscopy). Geologic context of the fossils and rock samples from measured sections will be established through geochemistry and sedimentology using mineral contents, stable isotopes, sedimentary structures, and trace fossils. Biostratigraphic context will be established using both macrofossils and microfossils (e.g., brachiopods, conodonts, vertebrate microremains).

The research team will provide photos of the locality and copies/reprints of all published materials to the community for their own records. Casts and photos of the most significant and best-preserved fossils from the locality will also be provided to the community and/or its school for educational purposes. The results of this research will be incorporated into graduate student theses, published in refereed journals and book chapters, and presented at international academic conferences.

The fieldwork for this study will be conducted from July 15, 2013 to July 30, 2013.