Whole-Plant Concept and Environment Reconstruction of aTelemachusConifer (Voltziales) from the Triassic of Antarctica

Abstract

We present a whole-plant concept for a genus of voltzialean conifers on the basis of compression/impression and permineralized material from the Triassic of Antarctica. The reconstruction of the individual organs is based on a combination of organic connections, structural correspondences, similarities in cuticles and epidermal morphologies, co-occurrence data, and ex situ palynology. The affiliated genera of organs include trunks, branches, and roots (Notophytum); strap-shaped leaves with parallel venation (Heidiphyllum compressions and permineralized Notophytum leaves); seed cones (Telemachus and Parasciadopitys); pollen cones (Switzianthus); and bisaccate pollen of Alisporites type. Structural similarities lead us to suggest that Parasciadopitys is the permineralized state of a Telemachus cone and should be treated as a junior synonym. Biotic interactions involving the reconstructed conifer genus include plant-insect interactions (oviposition by Odonata) and not less than five different types of plant-fungal interactions, including two distinct endomycorrhizal associations, two probable seed parasites, and epiphyllous fungi. A representative whole plant is reconstructed as a 10-15-m-tall, seasonally deciduous forest tree with a vertical, narrow-conical crown shape. We interpret these Telemachus trees as the dominant components of peat-forming conifer swamps, forest bogs, and immature bottomland vegetation in the Triassic high-latitude river basins of southern Gondwana. In architecture, growth habit, and many ecological characteristics, the Telemachus conifers appear to be comparable to extant larch (Larix). Owing to the large amount and often exquisite preservation of the material, this conceptual whole-plant genus represents one of the most completely reconstructed ancient conifer taxa to date.

Voltziales y Pinales (= Coniferales) de la Formación Cortaderita (Triásico Medio), Argentina, y su implicancia en la reconstrucción de las coníferas triásicas

“…Recientemente, se ha publicado una reconstrucción de la planta completa de una Voltziaceae del Triásico de Antártida, que vincula órganos con diferentes modos de preservación y que a su vez previamente habían sido relacionados a diversas familias (Escapa et al, 2010;Bomfl eur et al, 2013) Jersey, 1962). Sin embargo, la vinculación de estos órganos presenta algunas difi cultades, en particular porque no todos provienen de la misma unidad estratigráfi ca, y entre ellos existen diferencias signifi cativas a nivel anatómico, como es el caso de N. kraeuselii y P. aequata.…”

“…Anatómicamente, el xilema secundario de las Voltziales triásicas y de las Pinales podría presentar similitudes. De hecho, en otras regiones del Gondwana, se ha sugerido una reconstrucción en la que se vincula a Heidiphyllum/ Telemachus con troncos permineralizados, de características semejantes a los leños de las podocarpáceas (Axsmith et al, 1998;Escapa et al, 2010;Bomfl eur et al, 2013).…”

Habit and Ecology of the Petriellales, an Unusual Group of Seed Plants from the Triassic of Gondwana

“…This kind of preservation is exceedingly rare or unknown in all of the co-occurring gymnosperm foliage types (table 1). In addition, we found that detached petriellalean foliage in the Antarctic collections is always strongly fragmented and have never observed complete and isolated leaves, which, by contrast, is the common mode of leaf preservation of the co-occurring gymnosperms (Bomfleur , 2013aEscapa et al 2011). Furthermore, petriellalean compression fossils are overall notably rare, occurring in only 2 of 49 or more plant-fossil assemblages surveyed.…”

“…Furthermore, petriellalean compression fossils are overall notably rare, occurring in only 2 of 49 or more plant-fossil assemblages surveyed. They are absent in the typical "leaf-litter assemblages"-which accumulated during quiescent conditions through the physiological loss of leaves and reproductive organs of seasonally deciduous gymnosperm trees (table 1; Bomfleur et al 2011Bomfleur et al , 2013a)-and are preserved only in rather unusual plant-fossil assemblages; plant level 2 from the Allan Hills, for example, contains redeposited, complete fern rhizomes with attached fronds and croziers (T. N. Phipps et al 1998), subterranean organs of sphenophytes (Bomfleur et al 2013b), and abundant debris of leafy and thallose bryophytes (Bomfleur et al 2014a). At the Alfie's Elbow site, petriellalean remains occur only in the level 2 bed, which also yielded (1) the only known occurrence of corystosperm reproductive organs attached to short shoots Axsmith et al 2000Axsmith et al , 2007, (2) one of only three known occurrences worldwide of attached Dicroidium leaves (Axsmith et al 2000), and (3) the only known record of dipterid ferns in the Antarctic Triassic (Escapa et al 2011).…”

Mesozoic gymnosperms: megafloral changes through the Triassic–Jurassic of Eastern Gondwana

“…Pteruchus-like pollen is known from the Upper Permian through Lower Jurassic (Balme 1995) and the fructification had wide geographic extent in the Gondwanan Triassic (chiefly, Anisian-Norian: Anderson & Anderson 2003). Alisporites pollen has been affiliated with conifers and possibly ginkgophytes (Balme 1995, Bomfleur et al 2013 and has been identified from the Permian through Upper Cretaceous (Mohr & Gee 1992, Balme 1995.…”