Bomfleur, Benjamin , Decombeix, Anne-Laure , Taylor, Edith , Taylor, Thomas .
A review of the Petriellales, a group of Triassic gymnosperms from Gondwana.
We present a review of the Petriellales, an order of seed plants from the Triassic of Gondwana, based on newly identified material from Antarctica and a critical review of literature data. The group was established in 1994 with the description of Petriellaea triangulata, a permineralized cupulate organ from the Middle Triassic Fremouw Formation of East Antarctica. Petriellaea consists of clusters of presumably paired, multiovulate cupules, each containing five or six small, fully enclosed ovules that are triangular in cross section. Superficially similar ovulate structures in compression/impression preservation (Kannaskoppia) have subsequently been described to occur in organic connection with axes, leaves, and with associated pollen organs in the Molteno Formation of South Africa. The axes are slender and bear irregularly arranged, short protrusions, each giving rise to a leaf, reproductive organ, or both. The leaves - “described as 'Kannaskoppifolia', likely a junior synonym of Rochipteris - are apetiolate, and overall wedge-shaped with a variably incised, divided, to deeply dissected distal margin; the venation is fan-shaped, dichotomizing, and shows characteristic anastomosing patterns that appear to be typical of the group. Well-preserved leaf surfaces also show a particular type of epidermal gland. Pollen organs (Kannaskoppianthus) consist of a dichotomizing main axis with pinnately arranged, wedge-shaped microsporophylls; the concave lamina of each microsporophyll has been interpreted to contain a terminally attached, recurved group of five pollen sacs. A literature survey reveals that foliage, pollen organs, and possibly also ovulate organs that can now be confidently assigned to the Petriellales have been described from numerous Triassic deposits across Gondwana as early as the late 1800s. In most cases, the leaves had been tentatively assigned to Ginkgoales.
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1 - University of Kansas, Department of Ecology and Evolutionary Biology, and Natural History Museum and Biodiversity Institute, Haworth Hall, 1200 Sunnyside Avenue, Lawrence, KS, 66045, USA
2 - UMR AMAP, C/o CIRAD, TA A51/PS2, Bvd De La Lironde, Montpellier, N/A, F-34398, France
3 - University Of Kansas, Department Of Ecology And Evolutionary Biology, 1200 Sunnyside Avenue, Haworth Hall, Lawrence, KS, 66045-7600, USA
4 - University Of Kansas, Department Of Ecology And Evolutionary Biology, 1200 Sunnyside Avenue, Haworth Hall, Lawrence, KS, 66045-2106, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Union A/Hyatt
Date: Tuesday, July 10th, 2012
Time: 2:00 PM