Review of Systematic Ichnology of the Late Ordovician

Georgian Bay Formation of Southern Ontario, Eastern Canada,

by D. Christopher A. Stanley and Ron K. Pickerill  

Robert B. MacNaughton
Queenís University at Kingston
macnaugh@geol.queensu.ca


I have looked forward to the publication of Stanley and Pickerill's (1998) treatment of the ichnology of the Late Ordovician Georgian Bay Formation for several years now. As Chris Stanleyís one-time class-mate and Ron Pickerillís former student, I was at various times privy to tantalizing glimpses of the material, glimpses that left me eager to read the resultant monograph. Now that I have done so, I am happy to report that although the monograph breaks relatively little new ground, it provides a solid record of what is potentially a very significant ichnofauna.

The Georgian Bay Formation crops out in southern Ontario, Canada, and is of particular interest to ichnologists because it is of the same age and biogeographic province as the Cincinnatian succession in Ohio, the subject of Osgoodís (1970) classic trace-fossil monograph. The potential for comparison between the carbonate-dominated Ohio succession and the siliciclastic Georgian Bay Formation lends this monograph (a product of Stanleyís M.Sc. research) a very definite significance. In fact, this contribution represents the first systematic treatment of Georgian Bay Formation trace fossils since several specimens were described (as plants) in the mid-1920's.

Stanley and Pickerillís well-written monograph, together with the series of journal articles that preceded it into print, consists almost entirely of a very competent study of the systematic palichnology of the Georgian Bay Formation. It incorporates a re-examination of trace-fossil specimens from collections housed in the Royal Ontario Museum, as well as consideration of additional material collected by the authors.

The treatment of systematics is highly readable and contains some useful and interesting innovations. These include a potentially helpful simplification of the ichnotaxonomy of Cochlichnus, a report of shallow-marine specimens of Paleodictyon (discussed more fully in Stanley and Pickerill, 1993b), and the erection of Rusophycus osgoodii, named in honour of the late Richard Osgood. The reader is also pointed to several previous papers by the authors on the Georgian Bay Formation ichnofauna. These contributions renamed Micatuba as Arenituba (Stanley and Pickerill, 1995), proposed the new ichnospecies Planolites constriannulatus for specimens of Planolites showing concurrent striation and annulation (Stanley and Pickerill, 1994), and provided much-needed systematic reviews of Fustiglyphus and Rhabdoglyphus (Stanley and Pickerill, 1993a). In all, forty-seven ichnospecies are described. The descriptions are thorough and the ichnotaxonomic assignments are well-reasoned. My only serious reservation is that Stanley and Pickerill have probably been too optimistic in their treatment of one specimen, questionably assigned to Paleodictyon (?Paleodictyon isp. b; see Plate 9, Fig. 3), which looks more like an unusual physical sedimentary structure than a trace fossil. The photographic plates are exceptionally well composed (although the figured specimen of Cochlichnus anguineus would have benefited from greater enlargement). I only wish that they could have been printed on glossy paper--the material deserves it.

Thorough ichnotaxonomy is the strength of Stanley and Pickerillís contribution. Regrettably, however, once the ichnotaxonomy has been presented, any additional analysis is rather scant. The monographís endmatter consists of somewhat cursory treatments of the sedimentology and stratigraphy of the Georgian Bay Formation and of the larger significance of the ichnofauna. Although previous work on the sedimentology and stratigraphy of the succession is thoroughly referenced, the abstract actually contains more description of facies and depositional environments than does the main body of the text. And although a very useful tabulated comparison between the ichnofauna of the Georgian Bay Formation and of the Ohio Cincinnatian is presented in an appendix, the associated discussion amounts only to a single paragraph. Given the potential significance of their work, I hope that Stanley and Pickerill will consider presenting a more detailed comparison of the two successions at some time in the future.

Notwithstanding these reservations I am glad to own a copy of this monograph. To those of us for whom solid systematic ichnotaxonomy is a pleasure in its own right, Stanley and Pickerillís monograph will provide enjoyable and informative reading. Within the goals it sets for itself, this contribution succeeds admirably. I only regret that those goals were not set a bit higher.

 


References

  • Osgood, R. G., Jr. 1970. Trace fossils of the Cincinnati area. Palaeontographica Americana, 6(41): 276-444, pl. 57-83.

    Stanley, D. C. A., and Pickerill, R. K. 1993a. Fustiglypus annulatus from the Ordovician of Ontario, Canada, with a systematic review of the ichnogenera Fustiglyphus Vialov 1971 and Rhabdoglyphus Vassoievich 1951. Ichnos, 3: 57-67.

    Stanley, D. C. A., and Pickerill, R. K. 1993b. Shallow marine Paleodictyon from the Upper Ordovician Georgian Bay Formation of southern Ontario. Atlantic Geology, 29: 115-119.

    Stanley, D. C. A., and Pickerill, R. K. 1994. Planolites constriannulatus isp. nov. from the Late Ordovician Georgian Bay Formation of southern Ontario, eastern Canada. Ichnos, 3: 119-123.

    Stanley, D. C. A., and Pickerill, R. K. 1995. Arenituba, a new name for the trace fossil ichnogenus Micatuba Chamberlain, 1971. Journal of Paleontology, 69: 612-614.

    Stanley, D. C. A., and Pickerill, R. K. 1998. Systematic ichnology of the Late Ordovician Georgian Bay Formation of southern Ontario, eastern Canada. Royal Ontario Museum Life Sciences Contribution, no. 162, [3] + 56 pp., 13 pl. Toronto. [Available from: Royal Ontario Museum, 100 Queenís Park, Toronto, Ontario M5S 2C6, Canada.]


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