Habit and ecology of the Petriellales, an unusual group of seed plants from the Triassic of Gondwana

• Published in: International Journal of Plant Sciences
• Main Authors: Bomfleur, Benjamin, Decombeix, Anne-Laure, Schwendemann, Andrew B., Escapa, Ignacio H., Taylor, Edith L., Taylor, Thomas N., McLoughlin, Stephen
• Other Authors: Department of Ecology and Evolutionary Biology, University of Kansas, University of Kansas Lawrence (KU), Botanique et Modélisation de l'Architecture des Plantes et des Végétations (UMR AMAP), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut de Recherche pour le Développement (IRD France-Sud ), Lander University, Consejo Nacl Invest Cient & Tecn Museo Paleontol, Consejo Nacl Invest Cient & Tecn, Department of Palaeobiology Stockholm, Swedish Museum of Natural History (NRM), Alexander von Humboldt-Stiftung (Feodor Lynen fellowship); Agencia Nacional de Promocion Cientifica y Tecnologica (PICT-2010-2322); National Science Foundation (ANT-0943934); Swedish Research Council (VR)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: Polar forests; Antarctica; Gymnosperms; Petriellales; Triassic; Paleoecology; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; Antarc*
• Online Access: https://hal-sde.archives-ouvertes.fr/hal-01111107; https://doi.org/10.1086/678087

International audience Premise of research.Well-preserved Triassic plant fossils from Antarctica yield insights into the physiology of plant growth under the seasonal light regimes of warm polar forests, a type of ecosystem without any modern analogue. Among the many well-known Triassic plants from Antarctica is the enigmatic Petriellaea triangulata, a dispersed seedpod structure that is considered a possible homologue of the angiosperm carpel. However, the morphology and physiology of the plants that produced these seedpods have so far remained largely elusive.Methodology.Here, we describe petriellalean stems and leaves in compression and anatomical preservation that enable a detailed interpretation of the physiology and ecology of these plants.Pivotal results.Our results indicate that the Petriellales were diminutive, evergreen, shade-adapted perennial shrubs that colonized the understory of the deciduous forest biome of polar Gondwana. This life form is very unlike that of any other known seed-plant group of that time. By contrast, it fits remarkably well into the “dark and disturbed” niche that some authors considered to have sheltered the rise of the flowering plants some 100 Myr later.Conclusions.The hitherto enigmatic Petriellales are now among the most comprehensively reconstructed groups of extinct seed plants and emerge as promising candidates for elucidating the mysterious origin of the angiosperms