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Reference
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| Title: |
Report on Referred Fossils
,
1967
(09/08)
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| Report by: |
Norman J. Silberling
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| Referred by: |
C. C. Hawley
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| | Age: | Smithian (lower Smithian) |
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| Comment: | This fauna has close affinity with that of the Meekoceras gracilitatis Zone in the conterminous western U.S. as well as with that of the Euflemingites romunderi Zone of northeastern British Columbia and arctic Canada and Alaska. In the biostratigraphic classification of the North American marine Triassic by Silberling and Tozer (in press), these two zones are regarded as geographically distinct correlatives, both of which represent the lower Smithian Stage or about the middle of the Lower Triassic. Thus Mac Gordon's opinion o the age of this fauna, as stated in Tom Dutro's memo of 8/16/67, is confirmed. This occurrence of Smithian rocks in the Alaska Range has considerable paleogeographic significance, for correlative strata are known in Alaska only in the Brooks Ragne and North Slope, and are evidently not present in the upper Yukon area, Wrangell Mountains, Alaskan Peninsula, or in Southeastern Alaska where strata of late Middle Triassic or Late Triassic age rest directly on the Permian. Although only Dieneroceras, Prosphingites, and Arctoceras are well represented in this fauna, and comparisons are therefore uncertain, the ammonites present are in general more like those found in the Smithian at lower present latitudes in the conterminous U.S. than like those of the Smithian in Canada and northern Alaska. |
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