Growth habit indicators from Permian Antarctic glossopterids

Glossopteridales dominated the Gondwanan landscape during the Permian with Glossopteris leaves in mats suggesting a deciduous nature. While a great deal of anatomical and morphological information is known about the glossopterids, growth habit indicators have been limited to wood anatomical analyses and the presence of leaf mats. In this study the relative and absolute abundances were calculated on impression specimens collected from the Skaar Ridge locality in the Transantarctic Mountains, Antarctica. Results indicate that material is parautochthonous with layers dominated by either Glossopteris leaves or scale leaves. Three morphologies of scale leaves are present, two of which are associated with reproductive structures and one probably representing bud scales. Only pollen organ-bearing leaves have been observed on the specimens indicating that glossopterids may have been dioecious since ovulate material is not observed in any layer. A second hypothesis is that the glossopterids are monecious, but shed pollen structures early in the season and ovulate structures in the fall with Glossopteris leaves and just have not been observed in the leaf mats. The results from this study will help fill in gaps currently present for the glossopterids in phylogenetic analyses to help resolve their true position in a phylogenetic context. (c) 2017 Elsevier B.V. All rights reserved.