Abstracts
Geoff Creber
Geology Department, Royal Holloway University of London, Egham, Surrey
Schilderia adamanica and Woodworthia arizonica
are two of the tree species that grew in the Upper Triassic of what is now
Arizona USA. Each has its own special features. The trunk anatomy of
Schilderia is most unusual and also there is evidence of
penetration of the wood by arthropods. The wood of Woodworthia
has horizontal vascular traces which, in life, would have supplied epicormic
buds on the trunk surface.
Montserrat de la Fuente1, Carles Martín-Closas2 and Bernard Gomez3
(1) Unidad de Paleontología, Departamento de Biología, Universidad Autónoma de Madrid, 28049 Cantoblanco (Spain)
(2) Departament d'Estratigrafia, Paleontologia i Geociències Marines, Facultat de Geologia, Universitat de Barcelona,
08028 Barcelona (Catalonia, Spain)
(3) Bernard Price Institute for Paleontological Research, University of Witwatersrand, P.B. 3, 2050 Johannesburg (South Africa)
The Barremian lacustrine delta of Uña has been the subject of much interest since the seventies owing mainly to the presence of early mammal fossils associated with dinosaur remains, which were studied by Krebs and colleagues from the Freie Universität of Berlin (e.g. Krebs, 1980, 1993). Furthermore this delta displays particular sedimentological features, such as the accumulation of lignites in the deltaic front foresets (Gierlovsky-Kordesch et al., 1991). In the few last years we have focused our attention on the plant taphonomy of the Uña delta, including palynomorphs and macroremains (Gomez 2000, Gomez et al., 2001). In previous studies only the palynomorphs had been considered taxonomically (Mohr, 1987, 1989).
Our previous results showed that the Uña delta contained a monotypic taphofacies formed mainly by cheirolepidiaceous macroremains. Thus, fragmentary shoots of Frenelopsis associated with its male cones (Classostrobus) and rare remains of another conifer (Glenrosa) dominated the deltaic front and the crevasse-splay deposits of the lower deltaic plain. Macroremains were absent from other depositional environments in the deltaic plain. Gomez et al. (2001) concluded from their macroremain taphofacies analysis that the stream feeding the Uña delta was almost exclusively fed with cheirolepidiaceous remains which were supplied by stands of shrubs or trees living upstream, and probably forming low-diversity woodlands in the upper deltaic plain.
Additional data from palynofacies analysis has now enabled us to complete the picture. Two different palynofacies have been found in the Uña delta. Both are dominated by poorly preserved woody remains (poorly structured brown wood in the sense of Batten, 1996), which are in agreement with the general depositional environment, i.e. the deltaic context. The two palynofacies can be distinguished by secondary, but diagnostic, constituents. Palynofacies 1, which corresponds to lower deltaic plain deposits, contains abundant cuticles (up to 30 %) and palynomorphs (up to 20 %), the latter being mainly represented by schizaeaceous spores and tasmanitids (prasinophyte cysts). Other significant palynomorphs of this facies were matoniaceous spores and pollen of angiosperms. In contrast, palynofacies 2, belongs to the deltaic front lignites and is characterised by abundant amorphous organic matter (up to 60 %) and amber (up to 10 %). Rare palynomorphs of the palynofacies 2 almost exclusively belong to Classopollis as already noted by Gomez et al. (2001). The present results confirm our previous hypothesis that the Uña delta was almost exclusively fed by woody, cuticular and pollen remains, which Gomez et al. (2001) mainly attributed to Cheirolepidiaceae living in the upper deltaic plain. They shed, however, new light on the palaeoecology of the lower deltaic plain, which was extensively populated by herbaceous ferns (Schizaeaceae). Ponds in this part of the delta were temporarily eutrophic and allowed for the development of prasinophyte blooms.
References
BATTEN, D.J. 1996. Chapter 26A. Palynofacies and palaeoenvironmental interpretation. En: Jansonius, J. & McGregor, D.C.
(ed.), Palynology: principles and applications, American Association of Stratigraphic Palynologists Foundation, vol. 3, 1011-1064.
GIERLOWSKI KORDESCH, E.; GOMEZ FERNANDEZ, J.C. & MELENDEZ, N. 1991. Carbonate and coal deposition in an
alluvial-lacustrine setting: Lower Cretaceous (Weald) in the Iberian Range (East-Central Spain). En: Anadón, P.; Cabrera,
Ll. y Kelts, K. Lacustrine Facies Analysis. I.A.S. Special Publications, 13, 111-127.
GOMEZ, B.; MARTÍN CLOSAS, C.; MEON, H.; THEVENARD, F. y BARALE, G. 2001. Plant taphonomy and palaeoecology in the
lacustrine delta of Uña (Late Barremian, Iberian Ranges, Spain). Palaeogeogr., Palaeoclimatol., Palaeoecol., 170: 133-148.
KREBS, B. 1980. The search for mesozoic Mammals in Spain and Portugal. Mesozoic Vertebrate Life, 1, 23-25.
KREBS, B. 1993. Das Gebiss von Crusafontia (Eupantotheria, Mammalia) - Funde aus der Unter-Kreide von Galve und Uña (Spanien).
Berliner Geowissenchaftliche Abhandlungen, (E), 9, 233-252.
MOHR, B.A.R. 1987. Mikrofloren aus Vertebraten-fürenden Unterkreide-Schichten bei Galve und Uña (Ostspanien).
Berliner Geowissenschaftliche Abhandlungen, A (86), 69-85.
MOHR, B.A.R. 1989. New palynological information on the age and environment of the Late Jurassic and Early Cretaceous
vertebrate localities of the Iberian Peninsula (eastern Spain and Portugal). Berliner Geowissenschaftliche
Abhandlungen, A (106), 291-301.
Pinnatiramosus, a Llandovery vascular plant?
Dianne Edwards
Department of Earth Sciences, Cardiff University
Chinese assemblages of Silurian and Lower Devonian plants show such striking disparity that they have demanded reassessment
of evolutionary and geographic radiations of early land plants. Most spectacular of all, and occurring in Llandovery (basal
Silurian) rocks of Guizhou province, is Pinnatiramosus qianensis Geng which consists of an extensive vascularised axial system
showing complex pinnate branching. The latter is morphologically far more advanced than the strictly dichotomous branching
exhibited in slightly younger fossils believed to derive from the earliest tracheophytes, and the permineralised xylem possesses
tracheary pitting first documented in the Middle Devonian elsewhere. The orientation of the branches suggests that the fossils
are autochthonous, and not transported into the entombing marine rocks which are dated by brachiopoids. Following a field trip
to Guizhou I propose to evaluate evidence for two contrasting scenarios namely that the fossils were the rooting systems of
Llandovery plants or that they came from much younger plants which colonised weathered Silurian surfaces in the late Palaeozoic.
Christa-Charlotte Hofmann & Reinhard Zetter
Institute of Palaeontology, Geocentre, University of Vienna
A reinvestigation of the palynology of the modern sediments of the Orinoco delta complements the work of Jan Muller concerning the taxonomy and diversity of pollen grains. Surficial sediment samples taken from three deltaic environments (Cano Guaneiro, mangrove forest, and palm swamp) were studied with lightmicroscopy and SEM. The standing vegetational types of the sampling sites were reflected to different degrees (42-71%) by the palynomorph assemblages. Generally, the pollen and spore taxa preserved in all sediment samples reflected (a) the most abundant and most pollen producing taxa of the local and surrounding vegetation and (b) the taxa common along the distributaries in the delta. In each assemblage, 77-80% of the taxa are allochthonous or par-autochthonous and represent 36-78% of the pollen sum. In more open fluvial localities, these elements originated upstream and were transported by the river. Input of allochthonous palynomorphs into a more closed sedimentary system, such as a flood basin, is more restricted (36% of the pollen sum) and occurred mostly during floods. Floral composition also has an influence on the amount of autochthonous palynomorphs. The palynomorph assemblages from less diverse vegetational types (21-22 taxa) that are dominated by one or few taxa contain less allochthonous palynomorphs (39-36% of the pollen sum) than the assemblage of a diverse (>45 taxa) vegetation type that contains 78% of allochthonous palynomorphs.
Klaus-Peter Kelber
Institute of Mineralogy, University of Würzburg
Fossil charcoal (fusain), preserved in fluvial, lake and peat sediments have been yielded from the Erfurt-Formation (Lower
Keuper, Upper Ladinian), Stuttgart-Formation (Schilfsandstein, Carnian), Haßberge-Formation (Coburger Sandstein, Carnian?
Norian?) and the Exter-Formation (Rhaetian) of southern Germany. Broken chunks of charcolified wood, associated with
microbial mats also occur in chert beds of the Trossingen-Formation (Knollenmergel, Norian) from the Mainhardter Wald in Württemberg.
Fractured cubic charcoal pieces in size up to 3 x 3 x 2 cm have been resistant to compression and are three-dimensionally
preserved. These specimens are black and brittle, with silky luster. They display porosity from form of original cells.
SEM and reflective microscopy of cell walls shows clear evidence of cell wall homogenisation. Fluvial transportation is
well documented by rounded charcoal pieces.
The superb preservation achieved by charcolification enables exceptionally wood detail analysis, e.g. in revealing
uniseriate separate bordered pits and pit aperture characteristic in cross-field pits. So far as microscopically
scrutinized, all wood belongs to the genus Dadoxylon ENDLICHER. Growth rings in secondary wood indicate a degree of seasonality.
The charcolified wood remains, sourced from fire prone coniferopsid upland forests, suggest that
wildfire was an important environmental factor in germanotype Keuper ecosystems. Abundant quantities
of charcoal together with Semionotus bergeri and other fish remains from the Coburger Sandstein of
Ebelsbach (northern Bavaria) are interpreted as the result of a local catastrophic wildfire. Erosion after
wildfire might have induced nutrient flux into the water body. Then eutrophic processes have led to low
oxygen levels and triggered out massive fish kill.
Jiri Kvacek
National Museum, Prague
Peruc-Korycany Formation of the Bohemian Cretaceous Basin shows the best example of transgresive Cenomanian sequence and bears
the richest Cenomanian flora in Europe. The formation is outcropped in many localities distributed in the Northern part
of the Czech Republic. The most complete, and the largest section, is located at the Pecinov Quarry, 60 km west of Prague.
Multidisciplinary approach including palaeobotany, palynology, sedimentology, CLAMP C12/C13 analyses were employed
for understanding of palaeoenvironmental conditions of the Peruc-Korycany Formation in detail.
Our palaeoclimatic proxy data obtained by CLAMP reveal subtropical, periodically dry climate with mean annual temperature
17-20 ºC, warmth month mean temp. 22-24 ºC, cold month mean temp. 12-16 ºC, mean annual precipitation 1400-2250 mm, length
of the growing season 10-11 month.
The main recovered environments recorded in the Bohemian Cenomanian are occupied by the following plant assemblages:
A. Braided river assemblage (partly tidally influenced as documented by palynology) with prevailing lauroids: Myrtophyllum,
Grevilleophyllum, and Platanus, B. Meandring river assemblage with ferns (Schizeaceae - Schizeopsis, Anemia, Gleicheniaceae,
angiosperms Liriodendropsis, Debeya. C. Large river levee and floodplain assemblage with the cycad Microzamia gibba and
prevailing angiosperms Platanus bohemica, Debeya coriacea, Myrtophyllum geinitzii, "Aralia" kowalewskiana, Diplostrobus
stupeckyanus, D. Salt marsh assemblage with Frenelopsis alata, Eretmophyllum obtusum, Dammarites albens, Diospyros cretacea, E.
Swamp
assemblage with taxodiaceae conifers Cunninghamites lignitum, Quasisequoia crispa, Sequoia hetereophylla, F. Regression
marsh assemblage with Sphenolepis pecinovenisi, Cunninghamites lignitum, Brachyphyllum squamosum, Nilssoniopteris pecinovensis, G.
Unclassified upland vegetation, which is typical in presence of gymnosperms Zamites, Lindleycladus, Sagenopteris, Pinaceae and
small leaved angiosperms (Dicotylophyllum sp.)
Frenelopsis assemblage is typical for transgressive type of a coast with high level of underground water. The Sphenolepis
assemblage is typical for regressive sediments with falling level of underground water. Representatives of Lauraceae are typical
for disturbed habitats of braided rivers being in role of pioneers. The nutrient rich levee of large rivers bear the most diverse
broad-leaved angiosperms (e.g in the locality Vysehorovice).
C12 C 13 analysis showed succession of the salt marsh. Frenelopsis was front plant growing most seaward, then Eretmophyllum
and Pseudoasterophyllites and an ngiosperm "Dispyros" cretacea.
All the assemblages show prevailing angiosperm taxa in river sediments and their shortage in sea influenced sediments and swamps.
Old Lower Cretaceous taxa were recorded in many habitats (Nilsonia from fluvial sediments, Nilssoniopteris from marsh),
but they are most prominent in specialised habitats of salt marshes (Frenelopsis, Eretmophyllum) and drier uplands
(Zamites, Lindleycladus, Sagenopteris).
Imogen Poole1, Pim F. van Bergen1 and Miles Silman2
1 Department of Geochemistry Faculty of Earth Sciences, Utrecht University, P.O. Box 80021, 3508 TA Utrecht, The Netherlands.
2 Department of Biology, Wakeforest University, Box 7325 Reynolda Station, Winston-Salem,
NC 27109-7325 USA.
Reconstructing, along with subsequent refining and understanding, of past environments is one of the continual goals of palaeobotanical research. Such studies focus on the remains of plant organs which have been subject to taphonomic processes and thus biases. Conclusions from such studies are based on an underlying assumption that the preserved material is representative of the original, or parent, vegetation. In order to try and quantify this assumption a tropical river system in the Manu National Park, eastern Peru, was studied to determine the relationship between the plant material, namely propagules and wood, found along the river system and the parent vegetation growing in neighbouring forests. Plant family composition was found to differ significantly between the wood and propagule component thus highlighting the importance of looking at fruit and seed assemblages in conjunction with the wood assemblage when reconstructiong palaeoenvironments.
Pim F. van Bergen P.F. and Imogen Poole
Department of Geochemistry Faculty of Earth Sciences, Utrecht University, P.O. Box 80021, 3508 TA Utrecht, The Netherlands
Evidence for epiphytes and palms in the fossil record is scanty. Does this imply that epiphytes and palms are a feature of predominantly modern ecosystems, or that taphonomical biases have played a role in reducing the potential for incorporation into the fossil flora? Observations focusing on growth habit, habitat with the Cocha Cashu Biological Station within the Manu National Park and log jam (palisadas) from the neighbouring Manu river system in the Peruvian Amazon Basin was undertaken to help qualify and quantify the processes that may account for the presumed under representation of palms and epiphytes in fossil floras
Johanna H. A. van Konijnenburg-van Cittert
Department of Palaeobotany & Palynology, University of Utrecht
Most people working in the Mesozoic and certainly those studying the Triassic are familiar with the
Ladinian/Carnian (Lower Keuper) Lycophyte Annalepis zeilleri Fliche known from e.g. France an Germany.
This plant is only known from identical, ligulate mega- and microsporophylls including their mega- and microspores.
It has long been thought that this monospecific genus might be a guidefossil for the Lower Keuper floras in Europe,
but the recent discovery of similar, although smaller and especially more narrow Annalepis scales in the lower
Liassic strata near Bayreuth (Bavaria, Germany) extends the range of the genus into the Liassic.
The macromorphology of the new material will be discussed briefly, especially the apical extension preserved
in one specimen which is about as long as the rest of the cone scale and very thin. The imprint material has
been preserved in soft clays enabling the recovery of latex casts which demonstrate the epidermal structure
and the presence of microspores in some of the specimens.
This genus presents a taphonomic problem in so far that up till now only sporophylls have been found
and no vegetative parts of the plant, both in Annalepis zeilleri and in the new material. What can be the
reason for this? Are the vegetative parts so delicate that fossilisation is virtually impossible? When
we look at relatives that have also been found during mainly Triassic times, we see that members of the
Pleuromeiaceae (to which Annalepis is often assigned) are much better known, and also Isoetalean macrofossils are
well-known, often as whole plants, both from Triassic and Jurassic sediments. Even leaf cuticles have been recovered.
Retallack (1997) included A. zeilleri in the genus Lepacyclotes Emmons because of the similarity of the sporophylls.
Lepacyclotes is a lycopsid genus with leaves attached to a short lobed to rounded corm with fine adventitious roots.
The ligulate leaves are arranged in a terminal cluster with most apical leaves modified to sporophylls. The megasporophylls
more basally and the microsporophylls more apically placed. According to him, the foliage leaves are only few (and only
present in the type species L. circularis) and therefore, have often been overlooked. But neither corm, nor sporophylls
attached to some kind of structure have been preserved in Annalepis so far, and I do not believe that this attribution to
Lepacyclotes based on similarity of sporophylls, can be maintained unless the whole plant has been recovered. And this
leaves us again with the problem: why do we only have (numerous) sporophylls of these Annalepis species and no vegetative remains.
Ref.: Retallack, G.J., 1997. Earliest Triassic origin of Isoetes and quillwort evolutionary radiation. J. Paleont. 71(3): 500-521.
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CREBER, G.: Two unusual fossil Triassic tree species in the Petrified Forest
National Park, Arizona, USA