The graptolites " Pristiograptus " praedeubeli (Jaeger) and " Pristiograptus " ludensis (Murchison) (uppermost Wenlock, Silurian) from Arctic Canada: taxonomy and evolution
Isolated, uncompressed specimens of Pristiograptus dubius, "Pristiograptus" praedeubeli, and "Pristiograptus" ludensis are described from Arctic Canada. Pristiograptus dubius and early forms of "P." praedeubeli are very similar, suggesting a respective, ancestor-descend...
| Published in: | Canadian Journal of Earth Sciences |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
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Canadian Science Publishing
1994
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| Online Access: | http://dx.doi.org/10.1139/e94-125 http://www.nrcresearchpress.com/doi/pdf/10.1139/e94-125 |
| Summary: | Isolated, uncompressed specimens of Pristiograptus dubius, "Pristiograptus" praedeubeli, and "Pristiograptus" ludensis are described from Arctic Canada. Pristiograptus dubius and early forms of "P." praedeubeli are very similar, suggesting a respective, ancestor-descendant relationship. The study shows that "P." praedeubeli and "P." ludensis are generally readily distinguishable, but that the sicular region of the latter shows a much greater variation than previously recognized. End member morphs of "P." ludensis are remarkably similar to "P." deubeli, further confirming a close evolutionary link between them. To facilitate refined biostratigraphic division of the uppermost Wenlock, therefore, large collections of specimens are required to separate those two species when co-occurring. |
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