Anatomy and affinities of permineralized gymnospermous trunks with preserved bark from the Middle Triassic of Antarctica

• Published in: Review of Palaeobotany and Palynology
• Main Authors: Decombeix, Anne-Laure, Taylor, Edith L, Taylor, Thomas N.
• Other Authors: Department of Ecology and Evolutionary Biology, University of Kansas, University of Kansas Lawrence (KU), Department of Ecology and Evolutionary Biology, university of Kansas
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2010
• Subjects: [SDU.STU.PG]Sciences of the Universe [physics]/Earth Sciences/Paleontology; [SDV.BV.BOT]Life Sciences [q-bio]/Vegetal Biology/Botanics; Fremouw Peak; Transantarctic Mountains; Antarc*; Antarctica
• Online Access: https://hal.archives-ouvertes.fr/hal-00656922; https://hal.archives-ouvertes.fr/hal-00656922/document; https://hal.archives-ouvertes.fr/hal-00656922/file/2010_ALD_TNT_ELT_RPP_bark_webprint.pdf; https://doi.org/10.1016/j.revpalbo.2010.09.002

International audience Permineralized gymnosperm axes with pycnoxylic wood from the Middle Triassic Fremouw Formation of the Central Transantarctic Mountains, Antarctica, are assigned to the corystosperms (seed ferns) and conifers. Both groups have been previously described from this formation based on juvenile stems with attached leaf bases and decorticated trunks. Here we describe large axes with preserved bark from the Fremouw Peak permineralized peat locality. The specimens are characterized by a small parenchymatous pith with clusters of sclereids, a thick cylinder (> 10 cm) of pycnoxylic wood, and 1-2 cm of bark containing distinctive clusters of sclereids and a complex system of cortical vascular bundles. Comparison with axes previously described from the Middle Triassic of Antarctica shows that the new specimens are most similar to Kykloxylon, a corystosperm genus based on young stems bearing Dicroidium leaves, and with a portion of axis previously described as Rhexoxylon like. We suggest that both the new specimens and the Rhexoxylon-like axis represent proximal parts of a Dicroidium/Kykloxylon plant that possibly had a fluted trunk base, and we discuss the problem of delimiting features in corystosperm axes.