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Sunderlin, David, 2005

Permian phytogeographic patterns on northern Pangea with new data from the Alaska Range

Bibliographic Reference

Sunderlin, David, 2005, Permian phytogeographic patterns on northern Pangea with new data from the Alaska Range: Chicago, Illinois, University of Chicago, Ph.D. dissertation, 199 p., illust., maps, 1 CD-ROM.


Global phytogeographic patterning was well developed on Pangea by late Paleozoic time. The major phytogeographic provinces recognized in the Permian are Euramerica of equatorial mainland Pangea, Cathaysia of the low-latitude Tethyan islands, Gondwana of southern middle to high latitudes, and Angara of northern mid latitudes including Siberia, the Russian Platform, and associated regions. Description of an impression/compression flora from the Mt. Dall conglomerate in the Farewell Terrane of Alaska augments floral data coverage in northern Pangea in the Permian. The close biogeographic affinity of this flora with the Angaran phytogeographic province suggests (1) a temperate latitudinal position of the Farewell Terrane in the early Permian, and (2) that the locality is unique in that it represents a westernmost outpost of the Angaran phytogeographic province. The reported paleobiological collections constitute the youngest Paleozoic biogeographic datum of the Farewell Terrane as well as the only one from a primarily terrestrial biota. The intraregional phytogeography of Angara itself is also examined here using a large genus occurrence dataset (>2,200 occurrences) gathered from >190 published floral lists. The results of multivariate analyses of floral assemblages show the development of floristic variation in the region through the Permian, likely to have been driven by a combination of climate change and continental motion. A north-south gradient in floral composition along the Urals is persistent through ~40 million years of Permian time. Siberian and 'Sub-Angaran' assemblages show phytogeographic similarity through the middle stages of the Permian and differentiation in the earliest and latest Permian. The same dataset is used to analyze the geographic manifestation of the Paleophytic/Mesophytic floral transition in Angara. Mesophyte plant groups become taxonomically important in lower latitude assemblages earlier in the Permian than higher latitude assemblages, with some longitudinal variability. Paleophyte plant groups persist as dominant floral components in the highest latitudes into the latest Permian. The overall pattern suggests that the subtropics may have been a geographic source of land plant evolutionary novelty, perhaps initiated by lowland basin desiccation there that allowed plant forms formerly existing only in extrabasinal environments to take hold over a greater landscape range in lowland areas of high preservation potential.

NOTE: This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation.

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