A Dicroidium flora from the Triassic of Allan Hills, South Victoria Land, Transantarctic Mountains, Antarctica

Abstract

Chatterjee, S., Tewari, R. & Agnihotri, D., 2013. A Dicroidium flora from the Triassic of Allan Hills, South Victoria Land, Transantarctic Mountains, Antarctica. Alcheringa 37, 207-219. ISSN 0311-5518. A heterogenous and well-preserved assemblage of Triassic plants, including pteridophytes and gymnosperms, is described from the Lashly Formation of the Allan Hills, South Victoria Land, Antarctica. The pteridophytes include the sphenopsids Calamites aliwalensis, unidentified calamitalean axes, Neocalamites carreri and Neocalamites sp. The gymnosperms include Corystospermales, Peltaspermales and Pinales. Corystosperms dominate the megafloral assemblage and include Dicroidium odontopteroides, D. crassinervis, D. fremouwensis, D. coriaceum subsp. dutoitii, together with a microsporangiate structure Pteruchus sp. Peltaspermales include microsporangiate and ovuliferous reproductive structures namely Townrovia polaris and Matatiella dejerseyi, respectively. Conifers are represented by Heidiphyllum elongatum foliage and an unidentified cone. The megafossil assemblage is similar to those recorded from the late Early Triassic of New South Wales and Antarctica, Middle Triassic of Argentina, New Zealand and southeast Queensland, Middle to Late Triassic of South Africa, India, northern Argentina and Australia, early to middle Late Triassic of the central Transantarctic Mountains, Antarctica, and Late Triassic of Chile and North Victoria Land, East Antarctica. The records of Calamites aliwalensis, Neocalamites carreri, Dicroidium fremouwensis, Pteruchus sp., Townrovia polaris, Matatiella dejerseyi and a conifer cone are the first of these taxa from the Allan Hills. Recent finds from the Permian beds of India and Jordan indicate a much earlier origin of Dicroidium than previously suspected. Persistence of greenhouse conditions from the end of the Permian through the Triassic allowed the rich and diverse Dicroidium forests to develop in the polar regions of Antarctica. Sankar Chatterjee [sankar.chatterjee@ttu.edu], Texas Tech University, Lubbock, TX 79401, USA; Rajni Tewari [rajni.tewari@gmail.com], Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow 226007, India; Deepa Agnihotri [deepa_302033@yahoo.com], Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow 226007, India. Received 9.4.2012; revised 20.9.2012; accepted 2.10.2012.