Abstract Detail



Paleobotany

Ryberg, Patricia [1], Decombeix, Anne-Laure [2], Serbet, Rudolph [3], Taylor, Edith L. [4].

Silicified Permian Wood: High latitude diversity and environment indicators.

Permian Glossopteris floras are mostly represented by compression/impression fossils which  provide a wide range of glossopterid morphological  features; however, anatomically preserved specimens remain scarce.  Antarctica, on the other hand, includes several localities in which permineralized material with Glossopteris floral components are found, thus allowing for correlations between the morphology and anatomy of these Permian plants. Additionally, anatomical information has provided environmental clues of high-latitude environments. Interestingly enough, studies have mostly focused on the anatomy or the environment rather than the potential relationships between the two. Our goal is to examine the relationship between wood growth and structure and how it relates to various aspects of environmental conditions.
Fossils were collected from Mt. Sirius in the Beardmore Glacier region and has been dated to the Late Permian. The analyzed stems and branches contain conspicuous sclerotic nests in the pith, endarch primary xylem, and paired leaf traces. Of the eight wood genera previously reported from the Permian of Antarctica, these anatomical features suggest assignment to the genus Kaokoxylon, which was only represented in that part of Gondwana by a single specimen from nearby Coalsack Bluff.
The preservation of tree rings at Mt. Sirius is typical of Permian wood from Antarctica. Earlywood of most rings has been compressed creating the appearance of dark bands alternating with light bands. This diagenetic process has impeded most tree ring analyses on Permian wood across Gondwana. Fortunately several rings of Mt. Sirius Kaokoxylon specimens showed minimal damage and allowed for a more precise examination. Results reveal that cell lumen diameter decreases across a growth ring, but that cell walls maintain their thickness. This unusual wood growth challenges the traditional concept of earlywood (EW) and latewood (LW).  However, using a method developed especially for fossil wood analysis indicates that there is in fact a gradual transition from EW to LW. This indicates that the environmental conditions were indicative of a long growing season with an abundant availability of water. The current environmental reconstruction of the Antarctic Permian supports this EW/LW relationship. The extreme light regime at high latitudes where there is continuous sunlight for several months adds support to the long growth season concept. The new fossil trunks from Mt Sirius thus bring new information on the occurrence of Kaokoxylon in Antarctica and on the paleoenvironmental conditions that prevailed at the high latitudes in which these trees were growing.


1 - Park University, 8700 N.W. River Park Drive, Parkville, MO, 64152, United States
2 - CNRS, UMR AMAP, 9 Rue De Nazareth, Montpellier, 34, F-34398, France
3 - University Of Kansas, Division Of Paleobotany, Biodiversity Institute, 1200 Sunnyside Avenue, Lawrence, KS, 66045, United States
4 - University Of Kansas, Department Of Ecology And Evolutionary Biology, 1200 Sunnyside Avenue, Haworth Hall, Lawrence, KS, 66045, United States

Keywords:
Permian
Glossopteris flora
wood
extreme environment.

Presentation Type: Oral Paper
Number: 0004
Abstract ID:705
Candidate for Awards:None


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