Alaskan Cretaceous-Tertiary floras and Arctic origins

Cretaceous floras in Alaska, when compared to those at mid-latitudes, generally indicate later appearances in Alaska of major clades and major leaf morphologies. Compared to mid-latitude floras, Alaskan Late Cretaceous floras contain few major clades. The Alaskan clades diversified but at a low taxo...

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Bibliographic Details
Published in:Paleobiology
Main Authors: Spicer, Robert A., Wolfe, Jack A., Nichols, Douglas J.
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press (CUP) 1987
Subjects:
Online Access:http://dx.doi.org/10.1017/s0094837300008599
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0094837300008599
Description
Summary:Cretaceous floras in Alaska, when compared to those at mid-latitudes, generally indicate later appearances in Alaska of major clades and major leaf morphologies. Compared to mid-latitude floras, Alaskan Late Cretaceous floras contain few major clades. The Alaskan clades diversified but at a low taxonomic level. Migrational pathways into high latitudes were probably along streams. Similar patterns characterized the Alaskan Tertiary, although some southward migrations of lineages occurred during the Neogene. Review of other Arctic paleontological data from Ellesmere Island, previously used to suggest that the Arctic was a major center of origin during the Late Cretaceous, indicates that the ages of supposedly substantiating dinoflagellate floras were misinterpreted. When the dinoflagellate data are interpreted according to standard methodology, first occurrences of genera and species groups on Ellesmere are, like the Alaskan occurrences, later than first occurrences at middle latitudes.