Dr. Alfred C. Lenz

Paleontology

Professor Emeritus
Office: BGS 1000E
Phone: 1-519-661-3195
Fax: 1-519-661-3198
Email: aclenz@uwo.ca

Research Interests

My ongoing research basically revolves around a study of Wenlock to Lower Devonian graptolites of Arctic Canada. The Silurian of the Arctic Islands is now internationally renowned for its preservation of beautiful, three-dimensionally graptolites that may be released from limestones through acid dissolution. The beautiful preservation, and the fact that virtually the entire Silurian intermediate-depth sequences yield such graptolites, results in this being, arguably, the finest graptolite sequence in the world. In recent years, I have focussed on the late Wenlock and Ludlow part of the sequence and, in particular, on 1. the complex meshwork graptolites, the retiolitids, and 2. the profound graptolite extinction event near the end of the Wenlock in which 95% of all graptolites became extinct. It now is clear that not only was the extinction a traumatic event in the history of graptolites, but that in both the monograptid and retiolitid groups, post-extinction graptolite morphologies were distinctly different from those of the pre-extinction groups. Related to similar-aged graptolite sequences elsewhere in the world and to better understand the global nature of the extinction event, I have been collaborating with foreign workers; for example, A. Kozlowska-Dawidziuk and P. Štorch on a Barrandian sequence, Czech Republic; J-C. Gutiérrez-Marco and J-M. Piçarra in Spain and Portugal; and X. Chen, Y-N. Ni and Y-D. Zhang in China. Most recently, I have broadened the Arctic studies to involve specialists in other sub disciplines in an integrated study using several fossil groups, and combining this with geochemical analyses of the same strata. A. Kozlowska-Dawidziuk (Poland) joins me in studying the graptolites, P. Noble (University of Nevada/Reno) is studying radiolarians, A. Soufiane (Geological Survey of Canada, Quebec City) is studying palynomorphs, C. Barnes (University of Victoria) is studying conodonts, and C, Holmden (University of Saskatchewan) is carrying out geochemical analyses, particularly of δ¹³C and δ^18/16O. Results thus far are very promising, showing a strong δ¹³C excursion at about the extinction boundary, comparable to those elsewhere in the world. Our goal is now to extend the expanded and integrated study from the late Wenlock to the top of the Silurian basinal sequence. Ideally, the study should be able to compare faunal and floral dynamics with environmental changes shown by geochemical and sedimentological signatures and, from that, to better understand Silurian history of the Arctic.

Selected Publications

Lenz, A.C. and Kozlowska-Dawidziuk, A. 2002. Late Wenlock and Early Ludlow graptolite extinction, evolution and diversification: a reassessment. Studies in Palaeozoic palaeontology and biostratigraphy in honour of C.H. Holland. Special Papers in Palaeontology 67, p. 171-183.

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