The Possible Pollen Cone of the Late Triassic Conifer Heidiphyllum/Telemachus (Voltziales) From Antarctica

This is the publisher's version, which is being used with permission. The original article may be found at: http://dx.doi.org/10.1017/S0954102011000241Fossil leaves of the Voltziales, an ancestral group of conifers, rank among the most common plant fossils in the Triassic of Gondwana. Even though the foliage taxon Heidiphyllum has been known for more than 150 years, our knowledge of the reproductive organs of these conifers still remains very incomplete. Seed cones assigned to Telemachus have become increasingly well understood in recent decades, but the pollen cones belonging to these Mesozoic conifers are rare. In this contribution we describe the first compression material of a voltzialean pollen cone from Upper Triassic strata of the Transantarctic Mountains. The cone can be assigned to Switzianthus Anderson & Anderson, a genus that was previously assumed to belong to an enigmatic group of pteridosperms from the Triassic Molteno Formation of South Africa. The similarities of cuticle and pollen morphology, together with co-occurrence at all known localities, indicate that Switzianthus most probably represents the pollen organ of the ubiquitous Heidiphyllum/Telemachus plant

Systematics and Paleoecology of a New Peltaspermalean Seed Fern From the Triassic Polar Vegetation of Gondwana

This is the publisher's version, which has been shared with permission. The original version may be found at: http://dx.doi.org/10.1017/S0954102011000241A new Triassic seed fern is described on the basis of a large collection of well-preserved plant compressions from the Upper Triassic of Mt. Falla, Queen Alexandra Range, central Transantarctic Mountains. The foliage is simple entire-margined to pinnatifid to partly pinnate and is assigned to Dejerseya lobata (Jones et de Jersey) Herbst emend. nov. Associated with these leaves occur two new reproductive structures. The ovulate organ Matatiella dejerseyi sp. nov. is a lax, conelike structure with primarily shield-shaped megasporophylls that are dissected into three to four narrow lobes, each bearing a single recurved, naked ovule. The pollen organ Townrovia polaris sp. nov. consists of a slender axis arising from a covered reproductive bud, bearing pinnately arranged, stalked, elongate receptacles each with ;20 unilocular, clavate pollen sacs; the pollen is bisaccate nontaeniate with an irregular longitudinal sulcus and coarse saccus endoreticulations, corresponding to the dispersed pollen Falcisporites australis. Similar pollen grains occur in the micropylar canals of seed cuticles of M. dejerseyi. Co-occurrence data indicate that the three taxa are probably different organs from one plant species. This new seed fern is assigned to the Matatiellaceae, which we place into the Peltaspermales because of structural similarities with vegetative and reproductive organs of other peltaspermalean seed ferns. It appears that several Triassic Gondwanan plant fossil taxa of currently uncertain affinities—such as Pachydermophyllum, Linguifolium, Carpolithus mackayi, and Andersonia—may belong to the Matatiellaceae as well. We suggest that the matatiellacean peltasperms were opportunistic, early successional plants that were particularly successful in colonizing stressed wetland environments in polar latitudes during the Triassic

Early Jurassic silicified woods from Carapace Nunatak, South Victoria Land, Antarctica

The Jurassic vegetation of Antarctica remains poorly known and, while there have been several reports of large fossil trees from that time period across the continent, detailed anatomical studies of their wood are extremely scarce. Here we describe new silicified woods of Early Jurassic (probably Toarcian) age from Carapace Nunatak, South Victoria Land. The genera Agathoxylon and Brachyoxylon are formally recognized for the first time in the Jurassic of Antarctica. The preservation of the woods is imperfect, which is likely explained by the presence in some of the specimens of fungi, whose anatomical structures are described in detail. Combined with previous reports of pollen, leaves, and cones from South and North Victoria Land, these new specimens support the presence of several conifer families in the Early Jurassic floras of the region

Under pressure? Epicormic shoots and traumatic growth zones in high-latitude Triassic trees from East Antarctica

International audienceBackground and Aims: Investigating the biology of trees that were growing at high latitudes during warmer geological periods is key to understanding the functioning of both past and future forest ecosystems. The aim of this study is to report the first co-occurrence of epicormic shoots and traumatic growth zones in fossil trees from the Triassic of Antarctica and to discuss their biological and environmental implications.Methods : Permineralized woods bearing scars of epicormic shoots were collected from the Triassic Fremouw Formation in Gordon Valley, Central Transantarctic Mountains, Antarctica in 2010. Samples from different portions of three specimens were prepared using standard thin section and hydrofluoric (HF) acid peel techniques, and anatomical details were studied in transmitted light.Key Results: The fossil woods represent the outer part of trunks, with at least 40 growth rings that are 0.2–4.8 mm in width. Anatomical comparisons suggest that they represent a new tree taxon for the Triassic of Antarctica. Numerous small epicormic shoots can be seen crossing the wood almost horizontally and are locally branched. Each specimen also contains several occurrences of traumatic growth zones located in the early wood, in the cells produced either at the very start of the growing season or slightly later.Conclusions: This is the first report of epicormic shoots and traumatic growth zones in the wood of a Triassic tree from Antarctica. Their co-occurrence indicates that these trees from Gordon Valley were subjected to environmental stresses not seen in Triassic trees previously described from this region. This suggests that they had a different biology and/or were growing in a different habitat, which offers a new glimpse into the diversity of high-latitude trees in the Triassic greenhouse climate

(Table 1) Comparison of localities where Switzianthus (Anderson & Anderson) has been found with Dejerseya and Heidiphyllum occurrence

Fossil leaves of the Voltziales, an ancestral group of conifers, rank among the most common plant fossils in the Triassic of Gondwana. Even though the foliage taxon Heidiphyllum has been known for more than 150 years, our knowledge of the reproductive organs of these conifers still remains very incomplete. Seed cones assigned to Telemachus have become increasingly well understood in recent decades, but the pollen cones belonging to these Mesozoic conifers are rare. In this contribution we describe the first compression material of a voltzialean pollen cone from Upper Triassic strata of the Transantarctic Mountains. The cone can be assigned to Switzianthus Anderson & Anderson, a genus that was previously assumed to belong to an enigmatic group of pteridosperms from the Triassic Molteno Formation of South Africa. The similarities of cuticle and pollen morphology, together with co-occurrence at all known localities, indicate that Switzianthus most probably represents the pollen organ of the ubiquitous Heidiphyllum/Telemachus plant

Permian silicified trunks from Mt. Sirius, Central Transantarctic Mountains, Antarctica

International audienc

Additional observations on the enigmatic Permian plant Buriadia and implications on early coniferophyte evolution

An extensive collection of compressed altered remains, including leafy shoots and ovules similar to specimens described as Buriadia, is reported from Lower Permian rocks on Mount Gran, Victoria Land, Antarctica. The specimens, preserved as a thin layer of aluminosilicate film in a fine-grained black shale, show a number of morphological features like those reported from the type species, Buriadia heterophylla. The leaves are highly polymorphic and appear to be helically arranged. The ovules are orthotropous and attached to leafy shoots by a short stalk; they do not appear to be organized into distinct zones along the axis. The ovules are obovate, with a conspicuous bifid apex and prominent chalazal disk. The combination of features in these Antarctic specimens indicates affinities with the putative Permian coniferophyte, B. heterophylla, originally described from India. The discovery of a presumed coniferophyte with erect terminal ovules from the Permian of Antarctica adds support to the hypothesis that there were at least two major groups of conifer-like plants present during the late Paleozoic. Differences in the ovulate parts of these plants suggest a unique evolutionary history for the late Paleozoic coniferophytes from the Southern Hemisphere.Fil: Serbet, Rudolph. University of Kansas; Estados UnidosFil: Escapa, Ignacio Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Kansas; Estados Unidos. Museo Paleontológico Egidio Feruglio; ArgentinaFil: Taylor, Thomas N.. University of Kansas; Estados UnidosFil: Taylor, Edith L.. University of Kansas; Estados UnidosFil: Cúneo, Néstor Rubén. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Paleontológico Egidio Feruglio; Argentin

Skaar Ridge revisited: Insights into a Permian high latitude peat swamp forest ecosystem from Antarctica

International audienc

Triassic floras of antarctica: Plant diversity and distribution in high paleolatitude communities

Continental Triassic sequences in Antarctica are among the most continuous and best represented in Gondwana. Triassic fossil plants have been collected sporadically from Antarctica since the beginning of the twentieth century, but our knowledge of the vegetation during this time has dramatically increased during the last three decades. Here we review the fossil record of Triassic plants as representatives of natural groups from sites along the Transantarctic Mountains, using the fossils as evidence for successive vegetational changes through the Triassic, taking into account that these plant communities were living under particular high-latitude (706 or higher) paleoclimatological conditions, including a polar light regime. Even though our knowledge of the Triassic floras of Antarctica is still incomplete, this survey shows that these floras were remarkably diverse. Lycopsids, equisetaleans, ferns, seed ferns, ginkgoaleans, and conifers were major components of the landscape in Antarctica during this time. The diversity of gymnosperms is exceptional, with almost every major clade of seed plants present, despite the high paleolatitude; however, each clade is often represented by only one or a few genera. The occurrence of permineralized peat, along with compression-impression floras, has increased our knowledge of the morphology, reproductive biology, and evolution of many of the plants in these floras. In general, floral changes in Antarctica during the Triassic can be recognized elsewhere in Gondwana, especially in South America, although a strict correlation based on macrofossils is still not possible. Thus, this contribution represents the first attempt to bring together information on Triassic floras from continental Antarctica (excluding the Antarctic Peninsula) within a biostratigraphic framework and thereby to compare these floras with those from lower latitudes. Copyright © 2011, SEPM (Society for Sedimentary Geology.Fil: Escapa, Ignacio Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Paleontológico Egidio Feruglio; Argentina. University of Kansas; Estados UnidosFil: Taylor, Edith L.. University of Kansas; Estados UnidosFil: Cúneo, Néstor Rubén. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Paleontológico Egidio Feruglio; ArgentinaFil: Bomfleur, Benjamin. University of Kansas; Estados Unidos. Westfalische Wilhelms Universitat; AlemaniaFil: Bergene, Bergene. University of Kansas; Estados UnidosFil: Serbet, Rudolph. University of Kansas; Estados UnidosFil: Taylor, Thomas N.. University of Kansas; Estados Unido