Search

Conifers of the order Voltziales were important components of Triassic floras. Their pollen is likewise abundant in microfloras from this period. Voltzialean pollen grains are known to have a considerable range of morphologies, but taxonomic distinctions based on these differences require thorough descriptions of in situ pollen from well-preserved male cones. We studied the pollen grains extracted from male cones from the palaeofloras of the Dont Formation in Italy, the Grès à Voltzia in France (both Anisian, lower Middle Triassic), and the Erfurt Formation in Germany (Ladinian, upper Middle Triassic). Pollen cones from the Dont Formation contain taeniate bisaccate pollen that are otherwise known only from Paleozoic conifers, as well as in one case multi-taeniate pollen grains resembling those commonly associated with seed ferns. By contrast, in situ pollen grains from the Grès à Voltzia and the Erfurt Formation are mostly comparable to Illinites, Angustisulcites or alete forms such as Voltziaceaesporites, Alisporites, and Klausipollenites. Malformations are usually rare, but notable are recurring patterns of smaller or larger than normal corpus sizes, which could lead to different taxonomic assignments if found dispersed. Overall, pollen grain sizes in general can vary considerably within a sample and even more between samples from different specimens of the same species. By contrast, size ranges of different species are overlapping significantly.

The Middle to Upper Triassic successions of Europe have yielded several rich and well-preserved palaeofloras in which fertile fronds of marattialean ferns with conspicuous sporangia are common components. Here we describe the in situ spores of several marattialean fern species from these floras belonging to the genera Asterotheca, Merianopteris, Danaeopsis, and Symopteris with a focus on intra- and interspecific variability. Knowing this spore variability is important for the interpretation of dispersed spores and may provide insights into phylogenetic relationships and ecological influences. The spores of the various Asterotheca species are generally similar among each other, but Ladinian specimens are distinct as they have a punctate exine, whereas those from the Carnian are laevigate or microverrucate, rarely verrucate. Merianopteris augusta, long regarded as a junior synonym of A. merianii, differs markedly in the size and ornamentation of its spores. The spores of the various Danaeopsis and Symopteris species are generally circular, trilete, smooth-walled or discreetly ornamented, and mostly correspond to Todisporites or Punctatisporites. However, the rays of the trilete mark are often of unequal length. The various species mostly differ in the average size of the spores, but with notable outliers, potentially pointing to macromorphologically indistinguishable but biologically distinct lineages. In samples with sufficient yield, abnormally small, dense, and often dark spores that we interpret as abortive can be observed. These occur with frequency in every plant, usually in low frequencies, but with considerably high frequencies in a few individuals, which may indicate pathological conditions or natural hybridisation.

Spores or pollen from a single species or even an individual plant or sporangium may vary in morphology and size to a point that equivalent forms found dispersed in the sediment have been described as different species or even genera. In addition, not all these organs were mature at the moment of burial, and therefore they do not always contain completely developed microspores. To understand these variations better, we studied the intraspecific and interspecific morphological variability of in situ spores of leptosporangiate ferns (belonging to the Osmundales, possible Osmundales, and Gleicheniales) from the Triassic of Europe. The material comes from the Anisian Kühwiesenkopf/Monte Prà della Vacca flora of Italy and the Carnian Lunz flora of Austria. Our analysis is aimed at distinguishing the normal range of variability, differentiating developmental stages, and determining the frequency of abnormal spores. Results show significant variation in both size and surface ornamentation of spores from the same sporangia, as well as between sporangia and individuals, which may have various causes. Abortive spores are usually rare but occur with higher frequency in different samples from some specimens, suggesting that they can serve to identify systemic defects in the plants.

Altres ajuts: CERCA Programme/Generalitat de Catalunya, The Cisuralian-Guadalupian (early-middle Permian) was a period of climate transition between the Carboniferous icehouse conditions to the latest Permian-Early Triassic hothouse. The landmasses had coalesced in the supercontinent Pangaea and the climate was progressively becoming more arid, especially in a belt over the palaeoequator. The deposits of present-day Mallorca (Balearic Islands, western Mediterranean) were located in those low palaeolatitudes, in the western margin of the Tethys Sea, and correspond to alluvial systems with meandering rivers. The present study divides the stratigraphic succession into three main units, formally described herein as the Bec de s'Àguila Formation, Port des Canonge Formation and Pedra de s'Ase Formation. Based on an exhaustive review of the literature and new magneto- and biostratigraphic data, the sequence has been dated between the early and middle Permian (Artinskian-Wordian). Moreover, the detailed study of the fossils has provided a complete account of the denizens of those ecosystems. Tetrapod tracks occur abundantly in the Port des Canonge Formation, with morphotypes attributed to moradisaurine captorhinid eureptiles, araeoscelidian diapsids/non-varanodontine varanopids, possible pareiasauromorph parareptiles, "pelycosaur"-grade synapsids and indeterminate synapsids. Spores and pollen grains from the Pedra de s'Ase Formation indicate an overall dominance of conifers, accompanied by sphenophytes, ferns and seed ferns. Overall, apart from providing the first detailed interpretation of the ecosystems of the Permian of Mallorca, these new data have made it possible to improve the characterisation of the Permian-Triassic tectonosedimentary cycle in the Balearic Islands, which contribute to the understanding of the evolution of the western peri-Tethys ecosystems.

One of the most significant climate changes in the history of Earth happened during the late Palaeozoic, with the melting of the Gondwanan ice sheets and a progressive warming that profoundly changed the composition of the global terrestrial biota. Nevertheless, there is a lack of studies on mid-late Cisuralian central Pangaea (presentday Europe and North Africa). We have comprehensively revised the well-constrained tetrapod ichnofauna, macroflora, and microflora from the late Cisuralian of the Southern Alps and compared it to other Cisuralian assemblages from Europe and North Africa. The results show a dramatic increase in both diversity and relative abundance of drought-tolerant forms during the Artinskian, at about 287 Ma. This biotic replacement is sudden, conspicuous, widespread and time-equivalent to the biotic replacement observed at the low palaeolatitudes of western Pangaea (present-day western USA) and to a major increase of pCO2 and Na2O values in Euramerican successions. This is possibly related to the eruption of the Tarim Large Igneous Province of NW China and Panjal Traps of NW India that may have caused the final melting of the Gondwanan ice sheets. Consequently, this substantial faunal and floral change is probably driven by a global climatic event (Artinskian Warming Event, AWE) that increased temperature and aridity at the low palaeolatitudes of Pangaea, enhancing the apparent abundance and diversity of drought-tolerant taxa. Further studies are needed to better constrain the timing of this event and verify its full extent, in both the continental and marine realms, as well as to investigate its relationship with contemporary eruptions.

The Northern Hemisphere dominates our knowledge of Mesozoic and Cenozoic fossilized tree resin (amber) with few fndings from the high southern paleolatitudes of Southern Pangea and Southern Gondwana. Here we report new Pangean and Gondwana amber occurrences dating from ~230 to 40 Ma from Australia (Late Triassic and Paleogene of Tasmania; Late Cretaceous Gippsland Basin in Victoria; Paleocene and late middle Eocene of Victoria) and New Zealand (Late Cretaceous Chatham Islands). The Paleogene, richly fossiliferous deposits contain signifcant and diverse inclusions of arthropods, plants and fungi. These austral discoveries open six new windows to diferent but crucial intervals of the Mesozoic and early Cenozoic, providing the earliest occurrence(s) of some taxa in the modern fauna and flora giving new insights into the ecology and evolution of polar and subpolar terrestrial ecosystems., Tis publication represents aresearch output from Australian Research Council Discovery Grant ARC-DP140102515 (2014–2017) to J.S., D.B.and D.C., a Robert Blackwood Seed grant to J.S., and from Spanish AEI/FEDER, UE Grant CGL2017–84419 (theCRE project) to A.A. and E.P. Additional funds provided to C.M. for feldwork and preparation by the NationalGeographic Society (Grant 9761–15) and the Paleontological Society

The Northern Hemisphere dominates our knowledge of Mesozoic and Cenozoic fossilized tree resin (amber) with few fndings from the high southern paleolatitudes of Southern Pangea and Southern Gondwana. Here we report new Pangean and Gondwana amber occurrences dating from ~230 to 40 Ma from Australia (Late Triassic and Paleogene of Tasmania; Late Cretaceous Gippsland Basin in Victoria; Paleocene and late middle Eocene of Victoria) and New Zealand (Late Cretaceous Chatham Islands). The Paleogene, richly fossiliferous deposits contain signifcant and diverse inclusions of arthropods, plants and fungi. These austral discoveries open six new windows to diferent but crucial intervals of the Mesozoic and early Cenozoic, providing the earliest occurrence(s) of some taxa in the modern fauna and flora giving new insights into the ecology and evolution of polar and subpolar terrestrial ecosystems., Tis publication represents aresearch output from Australian Research Council Discovery Grant ARC-DP140102515 (2014–2017) to J.S., D.B.and D.C., a Robert Blackwood Seed grant to J.S., and from Spanish AEI/FEDER, UE Grant CGL2017–84419 (theCRE project) to A.A. and E.P. Additional funds provided to C.M. for feldwork and preparation by the NationalGeographic Society (Grant 9761–15) and the Paleontological Society

In this paper, we provide an overview of the historically known Triassic floras from the Eastern Southern Alps (e.g., Raibl and Recoaro), as well as the newer macro- and micro-plant assemblages that have been recorded during the 20th and 21st centuries. This includes some specimens stored in various European museums. The plant assemblages are presented here in chronostratigraphic order, starting with the Early Triassic, an interval of which only very few plant fragments are known from the area, whereas palynological data are available. In contrast to the Early Triassic, the Anisian floras (e.g., Kühwiesenkopf/Monte Prà della Vacca) are quite diverse, in both macrofloras – including in situ spores – and palynological assemblages. Similarly, the Ladinian of the Eastern Southern Alps is well known from the flora of Monte Agnello, which is outstanding in terms of both diversity and in total number of specimens, with additional information being derived from a large number of smaller macrofloral collections. The Carnian flora of the Eastern Southern Alps is also represented by a wide range of plant fossils, in contrast to the Norian/Rhaetian floras, which are represented only by a low number of macroremains and dispersed pollen and spores findings. A special subject of interest is the presence of amber in some of the Triassic sediments of the Southern Alps. Between the Wengen/La Valle and Heiligkreuz formations, the Dolomites represent the largest Triassic amber deposit known to date. In addition to macrofossil collections, the palynological data from many localities permits the reconstruction of environmental conditions during the various stages of the Triassic in the Southern Alps. They provide evidence for at least three shifts from xerophytic to hygrophytic palynoassemblages. Moreover, (chrono-)stratigraphic revision of the various localities enables a better understanding of the geographic and temporal dist