Palynology

Cambios vegetales holocenos en la región mediterránea de la Península Ibérica: ensayo de síntesis

by Santiago Riera

Santiago Riera
Revista Ecosistemas, ISBN 1697-2473, Nº 15 (1), 2006

La Península Ibérica se caracteriza por la diversidad de su paisaje vegetal y, a menudo, también por presentar una more La Península Ibérica se caracteriza por la diversidad de su paisaje vegetal y, a menudo, también por presentar una
fragmentación del mismo. Esta estructuración paisajística es el resultado de la confluencia de un conjunto de factores
topográficos, climáticos, microclimáticos, históricos, así como de una acción humana diversa y ejercida desde antiguo. La
acción integrada de estos factores ha conducido a una sectorialización del medio vegetal, así como también de los procesos de cambio ambiental.
Algunos estudios han puesto de manifiesto que la variabilidad natural de los cambios vegetales ha sido superior a lo largo del
Holoceno en los territorios mediterráneos que atlánticos (Fig. 1) (Julià et al., 2001; Riera y Julià, 2002). Las frecuencias de
cambio vegetal evidenciadas por los diagramas polínicos peninsulares se muestran en la Figura 1, apreciándose la existencia
de un mayor número de períodos de alta recurrencia de cambios en las áreas de bioclima mediterráneo (Rivas Martínez,
1987).

Late Cretaceous palynological correlation and environmental analyses of fluvial reservoir facies of the Tuna Field, Gippsland Basin, southeast Australia

by Stephen Gallagher

Überlegungen zur Verwendung pollenanalytischer Forschungen im Rahmen einer archäologischen Untersuchung der frühmittelalterlichen Landnutzung in Norddeutschland

by Anne Klammt

Veröffentlichung eines 2007 gehaltenen Vortrages.

Der Beitrag beinhaltet methodenkritische Überlegungen zur (unbedachten) Einbeziehung der Ergebnisse palynologischer... more Der Beitrag beinhaltet methodenkritische Überlegungen zur (unbedachten) Einbeziehung der Ergebnisse palynologischer Untersuchungen in siedlungsgeschichtlichen Studien. Der Schwerpunkt liegt auf der Auswertung von Pollenprofilen aus Seen und Mooren im Zuge archäologischer Untersuchungen. Näher betrachtet wird die Frage der Datierung, der räumlichen Tiefenschärfe und der Erkennbarkeit wirtschaftlicher Nutzungsstrategien. Der Beitrag richtet sich somit an die Archäologie und hier besonders die Siedlungsarchäologie. Sie stützt die eigene Argumentation vielfach auf die Ergebnisse palynologischer Untersuchungen, ohne die jeweiligen Parameter und Unsicherheiten der zugrundeliegenden Daten darzulegen.

Morphological trends in the fossil pollen of Decodon and the paleobiogeographic history of the genus

by Fridgeir Grimsson

2012
Fridgeir Grimsson, David K. Ferguson, Reinhard Zetter
International Journal of Plant Sciences

Eocene-Miocene carbon-isotope and floral record from brown coal seams in the Gippsland Basin of southeast Australia

by Stephen Gallagher

A new subdivision of the Albian spore-pollen zonation of Australia

by Stephen Gallagher

The Triassic-Jurassic boundary in the Danish Basin: implications on events of the end-Triassic mass extinction

by Sofie Lindström

Reference:
Lindström, S., Dybkjær, K., Pedersen, G.K., Nielsen, L.H., Erlström, M. & van de Schootbrugge, B. 2011: The Triassic-Jurassic boundary in the Danish Basin: implications on events of the end-Triassic mass extinction. FORCE Applications of biostratigraphy to the Norwegian Shelf. 8 December, 2011. Stavanger, Norway. Force/Norwegian Oil Directorate. Applications of biostratigraphy to the Norwegian Shelf, abstracts, 2-3.

The end-Triassic mass extinction event is estimated to have caused the disappearance of several marine families (23%)... more The end-Triassic mass extinction event is estimated to have caused the disappearance of several marine families (23%) and genera (50%) on a global scale (Hallam and Wignall, 1999; van de Schootbrugge et al. 2007). In the terrestrial realm regional to supraregional losses of vertebrate families (up to 42%) and plant species (up to 95%) have been recorded (McElwain et al, 1999, 2007; Olsen et al., 2002; Whiteside et al., 2007). The event is temporally linked to the flood basalt volcanism of the Central Atlantic Magmatic Province (CAMP)(Schoene et al. 2010) and major perturbations in the carbon cycle recorded in stable carbon isotope records globally are generally attributed to the effects of outgassing of 12C-enriched CO2 from this large igneous province (Hesselbo et al., 2002). However, recently injection of methane was put forward as a more likely cause for the most prominent C-isotope excursion, and thus also as a trigger of the end-Triassic mass extinction (Ruhl and Kürschner, 2011; Ruhl et al, 2011).

High resolution palynological and bulk organic C-isotope data from Triassic–Jurassic (T/J) successions in Denmark and Sweden provide evidence of major and partly coeval shifts in the marine and terrestrial palynofloras. The demise of typical Rhaetian dinoflagellate cysts and the temporary disappearance of these phytoplankton appear to coincide with an interval indicating terrestrial deforestation marked by a major decline in pollen from conifers, cycads and ginkgos. Instead high abundances of fern spores, the enigmatic pollen Ricciisporites tuberculatus and sphaeromorphs totally dominate the assemblages. Additional significant features of this interval within the basin, include increased erosion and reworking, changes in fluvial style and temporary loss of peat-forming vegetation.

Correlation between the organic C-isotope record and the terrestrial and marine biotic changes in the Danish Basin show that the major environmental perturbations took place prior to the most prominent negative C-isotope excursion. The subsequent reorganisation and recovery of the terrestrial ecosystem already commenced during this peak, hence negating injection of methane as a major cause of the end-Triassic mass extinction event. Instead we favour a scenario in which repeated episodic CO2 and SO2 release from the CAMP played a prominent role (van de Schootbrugge et al., 2009). Many of the changes recorded in the T/J-boundary succession of the Danish Basin can be attributed to outgassing of SO2 from the CAMP, and subsequent acid rain and acid deposition, and subsequent feedback effects.

References
Hallam, A. and Wignall, P.B. (1999). Mass extinctions and sea-level changes. Earth Sci. Rev., 48, 217-250.
Hesselbo, S.P., Robinson, S.A., Surlyk, F. and Piasecki, S. (2002). Terrestrial and marine extinction at the Triassic-Jurassic boundary synchronized with major carbon-cycle perturbations: A link to initiation of massive volcanism? Geology 30, 251-254.
McElwain, J.C., Beerling, D.J. and Woodward, F.I. (1999). Fossil plants and global warming at the Triassic-Jurassic boundary. Science 285, 1386-1390.
McElwain, J.C., Popa, M.E., Hesselbo, S.P., Haworth, M. and Surlyk, F. (2007). Macroecological responses of terrestrial vegetation to climate and atmospheric change across the Triassic/Jurassic boundary in East Greenland. Paleobiology 33, 547-573.
Olsen, P.E., Kent, D.V., Sues, H.D., Koeberl, C., Huberm H., Montanari, A., Rainforth, E.C., Fowell, S.J., Szajna, M.J. and Hartline, B.W. (2002). Ascent of dinosaurs linked to Ir anomaly at Triassic–Jurassic boundary. Science 296, 1305-1307.
Ruhl, M. and Kürschner, W.M., 2011, Multiple phases of carbon cycle disturbance from large igneous province formation at the Triassic-Jurassic transition: Geology, 39, p. 431-434.
Ruhl, M., Bonis, N.R., Reichart, G.-J., Sinninghe Damsté, J.S., and Kürschner, W.M., 2011, Atmospheric carbon injection linked to end-Triassic mass extinction: Science, v. 333, p. 430-434.
Schoene, B., Guex, J., Bartolini, A., Schaltegger, U. and Blackburn, T.J. (2010). Correlating the end-Triassic mass extinction and flood basalt volcanism at the 100 ka level. Geology 38, 387-390.
van de Schootbrugge, B., Tremolada, F., Bailey, T.R., Rosenthal, Y., Feist-Burkhardt, S., Brinkhuis, H., Pross, J., Kent, D.V. and Falkowski, P.G. (2007). End-Triassic calcification crisis and blooms of organic-walled disaster species. Palaeogeogr. Palaeoclimatol. Palaeoecol. 244, 126-141.
van de Schootbrugge, B., Quan, T.M., Lindström, S., Püttmann, W., Heunisch, C., Pross, J., Fiebig, J., Petschik, R., Röhling, H.-G., Richoz, S., Rosenthal, Y. and Falkowski, P.G. (2009). Floral changes across the Triassic/Jurassic boundary linked to flood basalt volcanism. Nature Geoscience 2, 589-594.
Whiteside, J.H., Olsen, P.E., Kent, D.V., Fowell, S.J. and Et-Touhami, M. (2007). Synchrony between the Central Atlantic magmatic province and the Triassic–Jurassic mass-extinction event? Palaeogeogr. Palaeoclimatol. Palaeoecol., 244, 345-367.

No causal link between terrestrial ecosystem change and methane release during the end-Triassic mass extinction

by Sofie Lindström

Reference:
Sofie Lindström, Bas van de Schootbrugge, Karen Dybkjær, Gunver Krarup Pedersen, Jens Fiebig, Lars Henrik Nielsen, and Sylvain Richoz, 2012: No causal link between terrestrial ecosystem change and methane release during the end-Triassic mass extinction. Geology 40 (6), 531-534, doi:10.1130/G32928.1.

Profound changes in both marine and terrestrial biota during the end-Triassic mass extinction event and associated... more Profound changes in both marine and terrestrial biota during the end-Triassic mass extinction event and associated successive carbon cycle perturbations across the Triassic-Jurassic boundary (T-J, 201.3 Ma) have primarily been attributed to volcanic emissions from the Central Atlantic Magmatic Province and/or injection of methane. Here we present a new extended organic carbon isotope record from a cored T-J boundary succession in the Danish Basin, dated by high-resolution palynostratigraphy and supplemented by a marine faunal record. Correlated with reference C-isotope and biotic records from the UK, it provides new evidence that the major biotic changes, both on land and in the oceans, commenced prior to the most prominent negative C-isotope excursion. If massive methane release was involved, it did not trigger the end-Triassic mass extinction. Instead, this negative C-isotope excursion is contemporaneous with the onset of floral recovery on land, whereas marine ecosystems remained perturbed. The decoupling between ecosystem recovery on land and in the sea is more likely explained by long-term flood basalt volcanism releasing both SO2 and CO2 with short- and long-term effects, respectively.

The dawn of terrestrial ecosystems on Baltica: First report on land plant remains and arthropod coprolites from the Upper Silurian of Gotland, Sweden

by Kristina Mehlqvist

Judging an acritarch by its cover: the taxonomic implications of Introvertocystis rangiaotea gen. et sp. nov. from the Late Cretaceous (Cenomanian–Turonian) of the Chatham Islands, New Zealand

by Chris Mays

A weird little guy which adds a new angle to the niche-universe of acritarch taxonomy.

You can access it online here:

http://www.tandfonline.com/doi/abs/10.1080/01916122.2011.633633

Described here is a small acritarch with a fine reticulation on the internal surface of the cyst wall which provides... more Described here is a small acritarch with a fine reticulation on the internal surface of the cyst wall which provides a
new criterion for future acritarch taxonomy. Sixty-six specimens of Introvertocystis rangiaotea gen. et sp. nov. have
been identified from sediments of Ngaterian to Arowhanan age (Cenomanian to early Turonian; c. 99–92 Ma) within
the Tupuangi Formation, Chatham Islands, New Zealand. The diagnostic feature of this fossil cyst is internal
reticulation. This requires the emendment of the genus Palaeostomocystis. Some specimens may show waist
constriction; this constriction is more common in larger specimens where it is suggestive of a paracingulum.
However, the absence of a definite paracingulum, parasulcus or definable archeopyle precludes its assignment within
the dinoflagellates. The wall structure is unusual in that the sculptural ornamentation is present on the internal
surface, a feature that distinguishes it from all known acritarch genera.

Historical context and chronology of Bronze Age land enclosure on Dartmoor, UK

by Thomas Roland

The upland of Dartmoor, southwest England, is one of the flagship prehistoric landscapes within Britain owing to the... more The upland of Dartmoor, southwest England, is one of the flagship prehistoric landscapes within Britain owing to the excellent survival of extensive prehistoric coaxial field systems. Archaeological surveys and rescue excavations during the 1970s and 1980s did much to further the understanding of this landscape; however, much remains to be explored, in particular the chronology of enclosure, the nature of the pre-enclosure landscape and the relationship between Bronze Age communities and their environment. Reconsideration of this landscape is important, given the place it holds in our understanding of subdivision of the landscape across northwest Europe during prehistory. This paper presents new palaeoecological data recovered as part of an integrated archaeological and palaeoecological project on northeast Dartmoor. The sequences detailed here include the first dated Neolithic period palaeoenvironmental data from within the prehistoric enclosed land on the moor, providing a longer-term context for enclosure. Neolithic groups are implicated in the first establishment of heathland in the study area at around 3630–3370 cal BC. During the early Bronze Age, reestablishment of hazel scrub in the study area implies reduced use of the upland, although it is not clear whether this is local or indicative of the wider landscape. A combination of pollen and fungal spore data indicates a substantial shift to species-rich grassland with grazing animals at c.1480 cal BC in a phase that lasted 400 years. The later Bronze Age and early Iron Age are characterised by low intensity use of the upland. These data provide new chronological data for land cover change on Dartmoor and whilst they broadly confirm existing models of upland land use in later prehistory, their proximity to the standing archaeology affords a more nuanced interpretation of local change.

Palaeovegetational reconstruction of the Hajdúnánás–Tedej–Lyukas-halom based on combined micropalaeobotanical analysis

by Ákos Pető

Pető, Á. – Cummings, L.S., 2011.Palaeovegetational reconstruction of the Hajdúnánás–Tedej–Lyukas-halom based on combined micropalaeobotanical analysis. In: Pető, Á. – Barczi, A. (Eds.) 2011. Kurgan Studies – An environmental and archaeological multiproxy study of burial mounds in the Eurasian steppe zone. British Archaeological Reports International Series 2238. Archaeopress, Oxford, UK., 315-325.

HERNÁNDEZ BELOQUI, B. 2012. Estudio palinológico de los espacios agrarios de Zaballa. En QUIRÓS CASTILLO, J. A. (ed.) Arqueología del campesinado medieval: La aldea de Zaballa. Universidad del País Vasco, Vitoria-Gasteiz, pp. 558-576.

by Begoña Hernández-Beloqui

Buying and Maintaining Nail Lacquer for Laboratory Use: A Practical Guide for Palynologists

by Maria Caffrey

Co-authored with Sally P. Horn

The evolution of the Australian flora: fossil evidence

by Stephen McLoughlin

Reference:
Hill, R.S., Truswell, E.M., McLoughlin, S. & Dettmann, M.E. 1999. The evolution of the Australian flora: fossil evidence. Flora of Australia, 2nd Edition, 1 (Introduction): 251-320.

The prehistory of the Australian vegetation is summarized – from the earliest traces of life in the Precambrian to the... more The prehistory of the Australian vegetation is summarized – from the earliest traces of life in the Precambrian to the events of the Cenozoic that shaped the continent’s modern flora. Australia’s oldest land plants appear in the Silurian with the rise of the lycophyte-dominated Baragwanathia flora. A succession of late Palaeozoic and Mesozoic pteridophyte- and gymnosperm-dominated floras followed, successive floras being punctuated by phases of major climate change and/or global mass-extinction events. For much of its Phenerozoic history, Australia has been part of the supercontinent Gondwana, thus it has shared broadly similar floras with the other Southern Hemisphere continents. The rise of the angiosperms in the Early Cretaceous was coincident with or slightly preceded the later stages of Gondwanan breakup. The modern angiosperm-dominated flora, therefore, developed during progressive isolation of Australia and its eventual collision with landmasses of southeast Asia. This history of isolation and amalgamation, together with the great climatic changes that have affected the continent over the past 100 million years, has set up intriguing scenarios for explaining the past and present distribution of a broad range of Australia’s plant taxa.

Deforestation of East–Bohemian lowland during the last two millennia: Interpretation of pollen record from the site „Na bahně“, Hradec Králové district

by Jaromír Beneš

Co-authored with P. Pokorný; Czech - English article from Archeologicke rozhledy jornal about human impact and ocupational intesity from La Tene Period until present

This article presents the results of pollen analyses at the East Bohemian lowland site of Na bahně near Hradec... more This article presents the results of pollen analyses at the East Bohemian lowland site of Na bahně near Hradec Králové, in comparison with analyses of the extensive archaeological assemblages from a wide area in eastern Bohemia. Radiocarbon dating has made it possible to synchronise the results of pollen
analyses with settlement evolution from the later Iron Age (La Tène period) to the present. The curves of settlement extent and the average representation of anthropogenic indicators mutually correspond. For the first time in the Czech Republic, it has thus been possible to demonstrate the decrease in human impact
on the landscape during the Migration Period. During the Early and (in particular) the High Middle Ages, on the hand, the pronounced synatrophisation of the landscape is clear, while during the Modern period there is a gradual transformation to the present situation.

Extinction and recovery patterns of the vegetation across the Cretaceous-Palaeogene boundary--a tool for unravelling the causes of the end-Permian mass-extinction

by Stephen McLoughlin

Reference:
Vajda, V. & McLoughlin, S. 2007. Extinction and recovery patterns of the vegetation across the Cretaceous–Palaeogene boundary — a tool for unraveling the causes of the end-Permian mass-extinction. Review of Palaeobotany and Palynology 144, 99–112.

High-resolution palynofloral signatures through the Cretaceous–Palaeogene boundary succession show several features in... more High-resolution palynofloral signatures through the Cretaceous–Palaeogene boundary succession show several features in common with the Permian–Triassic transition but there are also important differences. Southern Hemisphere Cretaceous– Palaeogene successions, to date studied at high resolution only in New Zealand, reveal a diverse palynoflora abruptly replaced by fungi-dominated assemblages that are in turn succeeded by low diversity suites dominated by fern spores, then gymnosperm- and angiosperm-dominated palynofloras of equivalent diversity to those of the Late Cretaceous. This palynofloral signature is interpreted to represent instantaneous (days to months) destruction of diverse forest communities associated with the Chicxulub impact event. The pattern of palynofloral change suggests wholesale collapse of vascular plant communities and short-term proliferation of saprotrophs followed by relatively rapid successional recovery of pteridophyte and seed–plant communities. The Permian–Triassic transition records global devastation of gymnosperm-dominated forests in a short zone synchronous with one or more peaks of the fungal/algal palynomorph Reduviasporonites. This zone is typically succeeded by assemblages rich in lycophyte spores and/or acritarchs. Higher in the succession, these assemblages give way to diverse palynofloras dominated by new groups of gymnosperms. Although different plant families were involved in the mass-extinctions, the general pattern of extinction and recovery is consistent between both events. The major difference is the longer duration for each phase of the Triassic recovery vegetation compared to that of the Paleocene. The protracted extinction-recovery succession at the Permian–Triassic boundary is incompatible with an instantaneous causal mechanism such as an impact of a celestial body but is consistent with hypotheses invoking extended environmental perturbations through flood-basalt volcanism and release of methane from continental shelf sediments.

Early Cretaceous (Neocomian) flora and fauna of the Lower Strzelecki Group, Gippsland Basin, Victoria

by Stephen McLoughlin

Reference:
McLoughlin, S., Tosolini, A.-M., Nagalingum, N.S. & Drinnan, A.N., 2002. The Early Cretaceous (Neocomian) flora and fauna of the lower Strzelecki Group, Gippsland Basin, Victoria, Australia. Memoirs of the Association of Australasian Palaeontologists 26, 1-144.

Fossil assemblages are described from the Tyers River Subgroup (late Berriasian to Hauterivian), Gippsland Basin,... more Fossil assemblages are described from the Tyers River Subgroup (late Berriasian to Hauterivian), Gippsland Basin, Victoria. The assemblages include plant macrofossils referable to 33 form-species including five new species (Isoetites abundans Tosolini & McLoughlin, Coniopteris victoriensis Nagalingum & McLoughlin, Otozamites douglasii Drinnan, Brachyphyllum tyersensis Tosolini & Nagalingum, Otwayia hermata Tosolini & McLoughlin) and three new combinations [Medwellia lacerata (Douglas) Nagalingum & McLoughlin, Rintoulia variabilis (Douglas) McLoughlin & Nagalingum, Pachydermophyllum austropapillosum (Douglas 1969) McLoughlin & Nagalingum]. Macrofossil assemblages include representatives of the Hepaticales, Isoetales, Equisetales, Filicopsida, seed-ferns, Coniferales and unionid bivalves. Co-preserved mesofossil suites include dispersed cuticle fragments, seed coats, seed megaspore membranes, microspore clusters, fern leptosporangia, charcoalified wood, resin blebs, epiphyllous fungal shields, clitellate annelid cocoons, insect exoskeleton fragments and coprolites. Sixteen lycophytic megaspore taxa were identified from the succession including six newly described species (Erlansonisporites confertus Tosolini, Favososporites brevis Tosolini, Hughesisporites australis Tosolini, Paxillitriletes rintoulensis Tosolini, Striatriletes imperfectus Tosolini, Trikonia locmaniensis Tosolini). These represent the first Neocomian megaspores formally described from Australia and their diversity and abundance indicates that lycophytes represented a significant component of the Early Cretaceous vegetation. The Tyers River Subgroup shares some taxa with the well-studied Koonwarra Fossil Bed (Aptian) flora of the Gippsland Basin but lacks several key elements (Ginkgoales, angiosperms and large-leafed araucarian conifers) and is more closely comparable to Jurassic floras of eastern Australia in its strong representation of bennettitalean, pentoxylalean and other seed-fern remains. The Tyers River Subgroup flora differs from coeval northwestern Australian floras by possession of smaller-leafed bennettites, Komlopteris and Pachydermophyllum species and by the lack of dipteridacean and gleicheniacean/lophosoriacean fern macrofossils. This intra-Australian provincialism is interpreted to be largely a function of palaeolatitude-induced climatic differences. Six major biofacies (one divisible into four sub-facies) are recognized in the Tyers River Subgroup and are attributable to three broad environmental settings within fluvial depositional tracts. Channel deposits host principally detrital plant remains derived from a broad range of riparian, upland, and reworked floodbasin communities. Silty floodbasin deposits typically host a mixture of pteridosperm-, fern- and lycophyte-dominated assemblages derived from a mosaic of herb-, shrub- and small tree-dominated communities developed mainly in perennially or seasonally wet environments. Better-drained, intervening levee, crevasse splay and neighbouring upland environments are interpreted to have hosted a conifer-dominated flora contributing to conifer-, root/rhizome-, megaspore-and clitellate-rich fossil associations. The floristic diversity, foliar morphology of selected species, strong representation of deciduous taxa and sedimentological data collectively suggest that seasonally cold conditions prevailed during the Neocomian-Aptian compared to the Albian in southeastern Australia.

Gondwanan floristic and sedimentological trends during the Permian–Triassic transition: new evidence from the Amery Group, northern Prince Charles Mountains, …

by Stephen McLoughlin

Reference:
McLoughlin, S., Lindström, S. & Drinnan, A.N., 1997. Gondwanan floristic and sedimentological trends during the Permian-Triassic transition: new evidence from the Amery Group, northern Prince Charles Mountains, East Antarctica. Antarctic Science 9, 281-298

The Permian-Triassic boundary within the Amery Group of the Lambert Graben is placed at the contact between the... more The Permian-Triassic boundary within the Amery Group of the Lambert Graben is placed at the contact between the Bainmedart Coal Measures and overlying Flagstone Bench Formation, based on the first regular Occurrence of Lunatisporites pellucidus and the first appearance of Aratrisporites and Lepidopteris species. The Permian-Triassic boundary is marked by the extinction of glossopterid and cordaitalean gymnosperms, and by the disappearance or extreme decline of a range of gymnospermous and pteridophytic palynomorph groups. Earliest Triassic macrofloras and palynofloras of the Flagstone Bench Formation are dominated by peltasperms and lycophytes; corystosperms, conifers, and ferns become increasingly common elements of assemblages through the Lower Triassic part of the formation and dominate floras of the Upper Triassic strata. The sedimentary transition across this boundary is conformable but marked by a termination of coal deposits; overlying lowermost Triassic sediments contain only carbonaceous siltstones. Typical redbed facies are not developed until at least 100 m above the base of the Flagstone Bench Formation, in strata containing ?Middle Triassic palynofloras. Across Gondwana the diachronous disappearance of coal deposits and appearance of red-beds is suggestive of a response to shifting climatic belts, resulting in progressively drier seasonal conditions at successively higher palaeolatitudes during the Late Permian to Middle Triassic. The abrupt and approximately synchronous replacement of plant groups at the Permian-Triassic boundary suggests that factors independent of, or additional to, climate change were responsible for the turnover in terrestrial floras.

An Early Jurassic flora from the Clarence-Moreton Basin, Australia

by Stephen McLoughlin

Reference:
Jansson, I.-M., McLoughlin, S., Vajda, V. & Pole M., 2008. An Early Jurassic flora from the Clarence-Moreton Basin, Australia. Review of Palaeobotany and Palynology 150: 5-21.

A low-diversity Early Jurassic flora preserved in floodbasin siltstones of the Marburg Subgroup at Inverleigh Quarry... more A low-diversity Early Jurassic flora preserved in floodbasin siltstones of the Marburg Subgroup at Inverleigh Quarry in the Clarence-Moreton Basin, eastern Australia, is dominated by Allocladus helgei Jansson sp. nov., a conifer with denticulate leaves tentatively attributed to Araucariaceae. The assemblage also includes Rintoulia variabilis and Caytoniales, (Caytonia cucullata McLoughlin sp. nov. and cf. Sagenopteris nilssoniana), reinforcing the wide distribution of this order in Early to Middle Jurassic floras of Gondwana. Ferns (Cladophlebis and Sphenopteris species) and isoetalean lycophytes (Isoetites sp.) constitute the herbaceous elements of the flora. The palynoflora is dominated by cheirolepidiacean (Classopollis) pollen and is attributable to the upper part of the Corollina (=Classopollis) torosa Zone of late Pliensbachian– early Toarcian age (180–185 Ma). The Inverleigh flora represents one of the few Australian assemblages dated between the major phases of floristic turnover at the end of the Triassic and the Toarcian. Sedimentological characteristics, cuticular features of the conifer leaves and the abundance of free-sporing plants indicate a relatively humid palaeoclimate for the Clarence-Moreton Basin Early Jurassic.