Abstract Detail

Paleobotany

Decombeix, Anne-Laure [1], Serbet, Rudolph [2], Taylor, Edith L [3], Taylor, Thomas N [3].

Triassic trees with epicormic shoots from Gordon Valley, central Transantarctic Mountains, Antarctica.

During the 2010-2011 austral field season, Triassic silicified wood and peat blocks were collected in the Antarctic locality of Gordon Valley, in the central Transantarctic Mountains. They occur within the upper Fremouw Formation, above the level from which an in situ corystosperm fossil forest was discovered in 1990-1991. Among the specimens are large pieces of decorticated gymnosperm trunks showing numerous small branch scars on their outside. Analysis of three specimens through peel-sections shows that they each had over 50 growth rings and thus represent mature trees. In transverse section, numerous epicormic shoots, some of them branching, cross the secondary xylem with a horizontal to oblique course. The center of the trunks is missing but information on the anatomy of the pith and primary xylem is available in the shoots. The pith is composed of parenchyma and conspicuous sclerotic nests. Only one large sclerotic nest can be seen on a given transverse section, and successive nests are regularly spaced when seen in longitudinal section. The secondary xylem is composed of tracheids and parenchymatous rays that are uniseriate and low. The radial walls of tracheids typically have one row of circular pits which are relatively crowded (araucarian) and have an oblique aperture. Cross-fields contain several crowded pits. All three specimens show some evidence of frost rings, sometimes with several in the same trunk, typically located within the earlywood. Our preliminary observations suggest that the trunks differ from arborescent taxa previously reported from the Fremouw Formation. Specifically, they can be distinguished from the conifer Telemachus/Notophytum by their wood and pith anatomy, and from the corystosperm Kykloxylon (=Jeffersonioxylon) by the lack of tangential and radial parenchymatous zones in their wood. The possible affinities of the trees will be discussed, as well as the new information they bring on epicormic shoots in extinct taxa and on Triassic paleoclimates of Antarctica..

1 - CNRS, UMR AMAP, C/o CIRAD, TA A51/PS2, Bvd De La Lironde, Montpellier, F-34398, France
2 - University Of Kansas, Division Of Paleobotany, Natural History Museum and Biodiversity Institute, 1200 Sunnyside Avenue, Lawrence, KS, 66045, USA
3 - University Of Kansas, Department Of Ecology And Evolutionary Biology, 1200 Sunnyside Avenue, Haworth Hall, Lawrence, KS, 66045-7600, USA

Keywords:
Triassic
Antarctica
Trees
wood anatomy
epicormic shoots
Frost rings
Mesozoic
Gondwana.

Presentation Type: Oral Paper
Session: 23, Paleozoic and Mesozoic Paleobotany
Location: 102/Savannah International Trade and Convention Center
Date: Tuesday, August 2nd, 2016
Time: 9:30 AM
Number: 23006
Abstract ID:128
Candidate for Awards:None