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  • 1. Hübers, M
    et al.
    Bomfleur, B
    Krings, M
    Pott, C
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Kerp, H
    A reappraisal of Mississippian (Tournaisian and Visean) adpression floras from central and northwestern Europe2014Ingår i: Zitteliana, Series A, ISSN 1612-412X, Vol. 54, s. 39-52Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mississippian plant fossils are generally rare, and in central and northwestern Europe especially Tournaisian to middle Visean fossil floras are restricted to isolated occurrences. While sphenophytes and lycophytes generally are represented by only a few widespread and long-ranging taxa such as Archaeocalamites radiatus, Sphenophyllum tenerrimum and several species of Lepidodendropsis and Lepidodendron, Visean floras in particular show a remarkably high diversity of fern-like foliage, including filiform types (Rhodea, Diplotmema), forms with bipartite fronds (Sphenopteridium, Diplopteridium, Spathulopteris, Archaeopteridium), others with monopodial, pinnate fronds (Anisopteris, Fryopsis) and still others characterized by several-times pinnate fronds (e.g., Adiantites, Triphyllopteris, Sphenopteris, Neuropteris). Most of these leaf types have been interpreted as belonging to early seed ferns, whereas true ferns seem to have been rare or lacking in impression/compression floras. In the upper Visean, two types of plant assemblages can be distinguished, i.e., the northern Kohlenkalk-type and the south-eastern Kulm-type assemblage. Although several compression/impression taxa have been revised in recent years to provide a more uniform classification, additional parameters such as different modes of preservation and imprecise information on stratigraphic age hamper detailed interregional comparisons of Mississippian floras.

  • 2. Launis, Ahti
    et al.
    Pott, Christian
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Mork, Atle
    A glimpse into the Carnian: Late Triassic plant fossils from Hopen, Svalbard2015Ingår i: Norwegian Petroleum Directorate Bulletin, ISSN 0808-1409, Vol. 11, s. 129-136Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A small number of well-preserved plant fossils have been collected during recent fieldwork on Hopen in the Svalbard archipelago. The assemblage shows a composition typical of Carnian floras from central Europe and complements a recent study of old collections of Upper Triassic plant fossils from Svalbard. The new findings include already described species and some possibly new for Svalbard. The plant fossils are from well-dated Carnian beds on Hopen and confirm the earlier assumed Carnian age for plants collected on Svalbard from Upper Triassic sediments. A remarkable feature of this flora is the high number of plants, which are also described from Carnian floras from Austria and Switzerland, but also recorded from Franz Josef Land and other Arctic areas. The stratigraphic value of this flora is discussed.

  • 3.
    Pott, C
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    A revision of Wielandiella angustifolia – a shrub-sized bennettite from the Rhaetian–Hettangian of Scania, Sweden, and Jameson Land, Greenland2014Ingår i: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 201, s. 75-105Artikel i tidskrift (Refereegranskat)
  • 4.
    Pott, Christian
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Westersheimia pramelreuthensis from the Carnian (Upper Triassic) of Lunz, Austria: More evidence for a unitegmic seed coat in early Bennettitales2016Ingår i: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 177, s. 771-791Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Premise of research. Isolated ovules and dispersed seeds have been obtained from bulk macerations of carbonaceousshales bearing fossil plants from the Carnian (Upper Triassic) flora of Lunz am See, Austria. Throughcuticle analysis, these well-preserved specimens were identified as ovules, interseminal scales, and seeds of Westersheimiapramelreuthensis, a peculiar bennettitalean ovuliferous organ. The preservation of several cuticularlayers enables for interpretation of the architecture of the ovules and seeds.Methodology. The excellently preserved plant fossils were investigated using LM and epifluorescence microscopyof cuticles. For comparison, the architecture of ovules and seeds of bennettitalean reproductive organsfrom Scania (Sweden), Jameson Land (Greenland), and Yorkshire (United Kingdom) were reevaluated.Pivotal results. The preserved layers indicate that the nucellus is surrounded by an integument, whose apicalend constitutes the micropyle. The single integument constitutes the monolayered seed coat in Westersheimia.The ovules and seeds are surrounded by interseminal scales. Of the latter, the cuticle is preserved that abutsthe ovule-seed surface, together with portions of the interseminal scale heads. The seeds provide additional informationon the cuticles of the nucellus or embryo.Conclusions. Studies of bennettitalean reproductive organs from Scania (Sweden), Jameson Land (Greenland),and Yorkshire (United Kingdom) facilitated reevaluation of the disputed architecture of bennettitalean seeds.The findings clearly indicate that early bennettitalean seeds can be interpreted as unitegmic.

  • 5.
    Pott, Christian
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Axsmith, Brian
    Department of Biology, University of South Alabama, Mobile, Alabama 36688, USA.
    Williamsonia carolinensis sp. nov. and associated Eoginkgoites foliage from the Upper Triassic Pekin Formation: Implications for early evolution in Williamsoniaceae (Bennettitales)2015Ingår i: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 176, s. 174-185Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Premise of research. Few reproductive organs unequivocally attributable to the important but enigmatic Mesozoic seed plant order Bennettitales have been described from the Triassic of all of North America outside of Greenland. Here, the first ovulate reproductive organs (gynoecia) of the group from the Upper Triassic of eastern North America are described and assigned to a proposed new species, Williamsonia carolinensis, of the family Williamsoniaceae.

    Methodology. The excellently preserved plant fossils were investigated using cuticular analysis and light, fluorescence, and scanning electron microscopy.

    Pivotal results. The description is based on 10 specimens from the Late Triassic (Carnian) Pekin Formation of North Carolina. They are interpreted as representing progressive developmental stages. Williamsonia carolinensis lacks a corona (sterile apical projection of the receptacle) and bracts subtending the receptacle. The lack of bracts is particularly unusual and appears to be the original condition and not apreservation artifact based on their absence even on immature specimens. The two largest specimens, interpreted as mature gynoecia, occur together on the same slab in exclusive association with the unusual bennettitalean leaf Eoginkgoites, suggesting that these organs were produced by the same parent plant species.

    Conclusions. The unique features of W. carolinensis, along with the probable affinity with Eoginkgoites foliage, expands the known diversity of the Williamsoniaceae and supports previous suggestions of remarkably high levels of morphological disparity in the earliest history of the Bennettitales.

  • 6.
    Pott, Christian
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Guhl, Michael
    Fachbereich Geowissenschaften der Universität Bremen, Postfach 330440, DE-28334 Bremen, Germany.
    Lehmann, Jens
    Fachbereich Geowissenschaften der Universität Bremen, Postfach 330440, DE-28334 Bremen, Germany.
    The Early Cretaceous flora from the Wealden facies at Duingen, Germany2014Ingår i: Review of Palaeobotany and Palynology, ISSN 0034-6667, E-ISSN 1879-0615, Vol. 201, s. 75-105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A middle latitude (c. 40° N) flora from the Lower Cretaceous of Duingen, north-western Germany, has been investigated. The newly collected fossils are preserved as impressions and compressions, some yielding cuticular details. Twenty-one species have been identified. The flora is dominated by ginkgophytes and conifers, whilst other groups such as Nilssoniales and Bennettitales represent minor portions of the vegetation. The bennettitaleans may be among the youngest of this group in Europe and one sphenophyte and a few ferns are also present. Two new species are described (viz. Nilssonia kurwia and Williamsonia joanwatsoniae) and one new combination (viz. Ptilophyllum aequale) is made. The composition of the flora is similar to that of other floras from the German Wealden, but exhibits certain differences from the English Wealden. The Duingen flora is compared to nearby and more remote Early Cretaceous floras of the Northern Hemisphere revealing a general need for revision of the German Wealden to improve correlation with more remote floras. The Duingen fossil flora derives from an established mixed temperate ginkgoalean–conifer forest with bennettites and Nilssoniales as minor, understorey components, most likely restricted to the moister coastal fringes of the forest.

  • 7.
    Pott, Christian
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Launis, Ahti
    Department of Biological and Environmental Sciences & Botanical Museum, P.O. Box 7, FI-00014, University of Helsinki, Finland.
    Taeniopteris novomundensis sp. nov. — "cycadophyte" foliage from the Carnian of Switzerland and Svalbard reconsidered: How to use Taeniopteris?2015Ingår i: Neues Jahrbuch für Geologie und Palaontologie - Abhandlungen, ISSN 0077-7749, Vol. 275, nr 1, s. 19-31Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recent findings of Taeniopteris-like foliage from the Carnian of Hopen, Svalbard, necessitated the re-evaluation of entire-margined Taeniopteris foliage from the Carnian flora of Neuewelt, Basel, Switzerland, revealing the illegitimate status of Taeniopteris angustifolia. The specimen from the Ladinian or Carnian (Lower Keuper) of Lower Franconia, Germany, on which the identification was based, was recently identified as the holotype of the marattialean fern Danaeopsis angustifolia, of which Taeniopteris angustifolia is the basionym. This implies that the Neuewelt specimens, which are different from the specimens from Franconia, lack any type and basionym, and a new species name is required. The specimens from Hopen as well as specimens elsewhere from Svalbard are identified as conspecific with the specimens from Neuewelt, and we here assign all specimens to Taeniopteris novomundensis sp. nov., which is thus known from the Carnian of Switzerland and Svalbard. Information on epidermal anatomy is not available, and the affinity of the species can, therefore, not be elucidated further, but is here interpreted as a cycadophyte. Several specimens from the Carnian of Franconia assigned to Taeniopteris angustifolia belong to a species different from Taeniopteris novomundensis, i.e. Taeniopteris kelberi. Earlier inclusion of some of the specimens now assigned to Taeniopteris novomundensis in Taeniopteris kelberi is unsupported. The typification and use of Taeniopteris are discussed in this framework.

  • 8.
    Pott, Christian
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    McLoughlin, Stephen
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Divaricate growth habit in Williamsoniaceae (Bennettitales): Unravelling the ecology of a key Mesozoic plant group2014Ingår i: Palaeobiodiversity and Palaeoenvironments, ISSN 1867-1594, Vol. 94, nr 2, s. 307-325Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Representatives of Williamsoniacae (Bennettitales) are usually restored as small-leafed shrubs or low-growing trees with densely interlaced stems bifurcating or trifurcating at broad angles —a growth form referred to as divaricating. A divaricate plant architecture has evolved independently in at least 18 modern plant families, of which the majority occur in New Zealand, where they constitute more than 10 % of the flora. Botanists favour two or three hypotheses on the benefits of a divaricating habit for modern plants. One hypothesis favours the evolution of this habit to protect the foliage and reproductive structures from browsing by large mammals or large flightless birds, such as the recently extinct moa or other ratites. Another argues that this habit evolved in response to a dry, windy or frosty climate, whereas a third regards divarication as having evolved to optimise foliar light harvesting. Our evaluation of these hypotheses with respect to the ecological pressures known to have been experienced by Williamsoniaceae in the mid-Mesozoic reveals that although defence against browsing tetrapods cannot be excluded as a selective pressure that promoted divarication in Williamsoniaceae, many of the anatomical and morphological features of this family appear to represent responses to local environmental conditions. In this context, representatives of Williamsoniaceae have many characters that are convergent with members of Banksiinae (Proteaceae), suggesting adaptation to open vegetation communities on nutrient-deficient soils.

  • 9.
    Pott, Christian
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Schmeissner, Stefan
    Dutsch, Guenter
    Van Konijnenburg-Van Cittert, Johanna HA
    Bennettitales in the Rhaetian flora of Wüstenwelsberg, Bavaria, Germany2016Ingår i: Review of Palaeobotany and Palynology, ISSN 0034-6667, E-ISSN 1879-0615, Vol. 232, s. 98-118Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The diverse bennettitalean plant remains from the Rhaetian of Wüstenwelsberg, Franconia, southern Germany,are described by means of macromorphological and epidermal anatomy; the study is part of the ongoing examinationof this recently excavated and excellently preserved fossil flora. The taxa identified include four species ofPterophyllum, one species of Anomozamites, two species of Nilssoniopteris and one species of Wielandiella withsterile leaves, bracts and ovulate reproductive organs. In addition, an enigmatic type of bennettitalean microsporangiateorgan has been obtained, remains of which from the Rhaetian of Greenland had been assigned toBennettistemon. However, the material from Wüstenwelsberg is much more complete and is assigned to a newgenus, viz. Welsbergia gen. nov., with its type species Welsbergia bursigera (Harris) comb. nov., based on theorgan's unique architecture. The microsporangiate organs are always exclusively associated with the sterile foliagePterophyllum aequale. Comparison of the flora fromWüstenwelsbergwith adjacent Rhaetian floras revealeddistinct local differences in the bennettitalean constitution, which are discussed in the light of palaeogeographyand plant dispersal patterns.

  • 10.
    Pott, Christian
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Van der Burgh, J
    Van Konijnenburg-van Cittert, JHA
    New ginkgophytes from the Upper Triassic–Lower Cretaceous of Spitsbergen and Edgeøya (Svalbard, Arctic Norway): The history of Ginkgoales on Svalbard.2016Ingår i: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 177, nr 2, s. 175-197, artikel-id 10.1086/684194Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Premise of research. During the ongoing investigation of Upper Triassic–Lower Cretaceous plant macrofossilsfrom Svalbard, Norway, some ginkgoalean leaf fossils were found from Carnian and Aptian deposits ofSpitsbergen and Edgeøya that represent newginkgophyte species. One newspecies is described as Baiera aquiloniasp. nov., and one ginkgophyte leaf is assigned to Ginkgoites sp. Along with the description of the new material,an overview of the presence and distribution of ginkgophytes in the high-latitude ecosystems of Svalbard throughtime is provided.Methodology. The plant macrofossils have been analyzed with transmitted-light and epifluorescence microscopy.Attempts to isolate cuticles were made.Pivotal results. The investigation resulted in the description of one species new to science, Baiera aquiloniasp. nov., and one specimen assigned to Ginkgoites sp. The presence of ginkgophytes on Svalbard changed significantlythrough time: periods of dominance and wide distribution interchanged with periods of very lowdiversity and abundance.Conclusions. Ginkgophytes were thriving in Svalbard, which was already located above 607N by the Carnian,from the Late Triassic to the Cenozoic in varying abundance and were finally extirpated, probably as a result ofdramatic climatic changes at the end of the Paleogene

  • 11.
    Pott, Christian
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Van der Burgh, Johan
    Van Konijnenburg-van Cittert, Johanna HA
    NEW GINKGOPHYTES FROM THE UPPER TRIASSIC–LOWER CRETACEOUS OF SPITSBERGEN AND EDGEØYA (SVALBARD, ARCTIC NORWAY):THE HISTORY OF GINKGOALES ON SVALBARD2016Ingår i: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 177, nr 2, s. 175-197Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Premise of research. During the ongoing investigation of Upper Triassic–Lower Cretaceous plant macrofossilsfrom Svalbard, Norway, some ginkgoalean leaf fossils were found from Carnian and Aptian deposits ofSpitsbergen and Edgeøya that represent newginkgophyte species. One newspecies is described as Baiera aquiloniasp. nov., and one ginkgophyte leaf is assigned to Ginkgoites sp. Along with the description of the new material,an overview of the presence and distribution of ginkgophytes in the high-latitude ecosystems of Svalbard throughtime is provided.Methodology. The plant macrofossils have been analyzed with transmitted-light and epifluorescence microscopy.Attempts to isolate cuticles were made.Pivotal results. The investigation resulted in the description of one species new to science, Baiera aquiloniasp. nov., and one specimen assigned to Ginkgoites sp. The presence of ginkgophytes on Svalbard changed significantlythrough time: periods of dominance and wide distribution interchanged with periods of very lowdiversity and abundance.Conclusions. Ginkgophytes were thriving in Svalbard, which was already located above 607N by the Carnian,from the Late Triassic to the Cenozoic in varying abundance and were finally extirpated, probably as a result ofdramatic climatic changes at the end of the Paleogene.

  • 12.
    Pott, Christian
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Van Konijnenburg-van Cittert, Johanna HA
    Kustatscher, Evelyn
    Schmeissner, Stefan
    Dutsch, Guenther
    Krings, Michael
    New data on Selaginellites coburgensis from the Rhaetian of Wüstenwelsberg (Upper Franconia, Germany).2016Ingår i: Neues Jahrbuch für Geologie und Palaontologie - Abhandlungen, ISSN 0077-7749, Vol. 280, s. 177-181Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A branched shoot with several attached microsporangiate strobili of the Rhaetian (late Triassic) herbaceous lycophyte Selaginellites coburgensis is described from Wüstenwelsberg near Coburg, Germany, the locus typicus of the species. The strobili all contain Uvaesporites-type microspores, precisely as the single, detached strobilus fragment found in association with one of the original specimens

  • 13.
    Pott, Christian
    et al.
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Wang, Xiaoli
    Linyi University, Institute of Geology and Paleontology, Linyi, Shandong, 276005, China.
    Zheng, Xiaoting
    Shandong Tianyu Museum of Natural History, Pingyi, Shandong, 273300, China.
    Wielandiella villosa comb. nov. from the Middle Jurassic of Daohugou, China: More evidence for divaricate plant architecture in Williamsoniaceae2015Ingår i: Botanica Pacifica, ISSN 2226-4701, Vol. 4, nr 2, s. 137-148Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently discovered fossils yielding branched axes with attached foliage are described from the Middle Jurassic Daohugou beds, Inner Mongolia, China. The leaves of the plant were earlier described as isolated and disarticulated foliage and assigned to Anomozamites villosus; the plant architecture, however, necessitates the re-assignment of the fossils under study to Wielandiella, a bennettitalean whole-plant fossil taxon that includes stems, leaves and unisexual ovuliferous repro-ductive structures. Wielandiella villosa is the second known species attributable to Wielandiella and extends the taxon’s range from the Rhaetian into the Middle Jurassic. Wielandiella villosa is interpreted to encompass specialised shrubs that are regarded to have thrived in swampy settings but also potentially extended to other lowland habitats, especially where conditions of physiological drought prevailed; conditions that, in modern vegetation, are considered to favour the development of divaricate plant growth forms. The foliage and reproductive organs of these medium-sized shrubs would have been of suitable size for ground-based animals to browse, potentially also stimulating a divaricate growth form in Wielandiella villosa. The ecological pressures promoting indumentum development and the protruding hairs on the leaves of Wielandiella villosa are interpreted as predominant-ly an adaptation for passive defence against herbivores rather than xeromorphic features. The latter add to ongoing investigations of the depositional setting of the fossils in order to unravel the plant’s habitat and micro-climate at Daohugou.

  • 14. Van Konijnenburg-van Cittert, JHA
    et al.
    Kustatscher, Evelyn
    Bauer, Kathleen
    Pott, Christian
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Schmeissner, Stefan
    Dütsch, Günter
    Krings, Michael
    A Selaginellites from the Rhaetian of Wüstenwelsberg (Upper Franconia, Germany)2014Ingår i: Neues Jahrbuch für Geologie und Palaontologie - Abhandlungen, ISSN 0077-7749, Vol. 272, s. 115-127Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Sterile shoots and a microsporangiate strobilus of a new herbaceous lycophyte, Selaginellites coburgensis nov. spec., are described from the Rhaetian (uppermost Triassic) of Wüstenwelsberg near Coburg, Germany. Shoots branch dichotomously and bear two lateral rows of larger and two median rows of smaller microphylls. Sporophylls are scale-like; sporangia contain Uvaesporites-type spores, which permit a direct comparison of macrofossil evidence with the dispersed spore record. Sellaginellites coburgensis is significant because lycophyte macrofossils are exceedingly rare in the Rhaeto-Liassic of Franconia. The plant probably grew in habitats that were shady and relatively humid, perhaps within dense vegetation and/or in close proximity to bodies of water that locally provided a favourable microclimate.

  • 15. Zaton, M
    et al.
    Niedzwiedzki, G
    Marynowski, L
    Benzerara, K
    Pott, Christian
    Naturhistoriska riksmuseet, Enheten för paleobiologi.
    Cosmidis, J
    Krzykawski, T
    Filipiak, P
    Coprolites of Late Triassic carnivorous vertebrates from Poland: An integrative approach2015Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 430, s. 21-46Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Vertebrate coprolites derived from Upper Triassic terrestrial deposits of southern Poland have been subjected to various analytical methods in order to retrieve information about their composition, producer’s diet and nature of the microscopic structures preserved in the groundmass. Morphologically, the coprolites have been classified into four morphotypes, of which only three were further analysed due to their good state of preservation. Their groundmass are composed of francolite, a carbonate-rich apatite, in which abundant coccoid structures are preserved. Based on various microscopic and organic geochemical techniques, they are interpreted as fossilized bacteria which could have mediated the phosphatization of the faeces. The thin sectioning revealed that the coprolites consist of those containing exclusively bone remains, and those preserving both bone and plant remains. Those coprolites preserving only vertebrate remains are suggestive for exclusive carnivorous diet of the producers. However, the interpretation of coprolites consisting of both vertebrate and plant remains is more debatable. Although they may attest to omnivory, it cannot be excluded that potential producers were carnivorous and occasionally ingested plants, or accidentally swallowed plant material during feeding. The latter may involve predation or scavenging upon other herbivorous animals. The potential producers may have been animals that foraged in or near aquatic habitats, such as semi-aquatic archosaurs and/or temnospondyls. This is supported by the presence of ostracode and other aquatic arthropod remains, and fish scales within the coprolites, as well as by the presence of specific biomarkers such as phytanic and pristanic acids, which are characteristic constituents of fish oil. The preservation of such labile organic compounds as sterols, palmitin, stearin or levoglucosan attests for rapid, microbially-mediated mineralization of the faeces at very early stages of diagenesis.

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