Recognizing pulses of extinction from clusters of last occurrences

The distribution of last occurrences of fossil taxa in a stratigraphic column are used to infer the pattern, timing and tempo of extinction from the fossil record. Clusters of last occurrences are commonly interpreted as an abrupt pulse of extinction. However, stratigraphic architecture alone can produce clusters of last occurrences that can be misinterpreted as an extinction pulse. These clusters will typically occur in strata that immediately underlie facies changes and sequence‐stratigraphic surfaces. It has been proposed that a basin‐wide analysis of the fossil record within a sequence‐stratigraphic framework can be used to distinguish between clusters of last occurrences caused solely by extinction pulses from those generated by sequence‐stratigraphic architecture. A basin‐wide approach makes it possible to observe lateral facies shifts in response to sea‐level change, mitigating the effects of stratigraphic architecture. Using computer simulations of plausible Late Ordovician mass‐extinction scenarios tuned to an inferred Late Ordovician sea‐level curve, we show that stratigraphically‐generated clusters of last occurrences are observed even in basin‐wide analyses of the simulated fossil records due to the basin‐wide loss of preferred facies for many taxa. Nonetheless, we demonstrate that by coarsening the stratigraphic resolution to the systems‐tract level and identifying facies preferences of simulated taxa, we can filter out taxa whose last occurrences coincide with the basin‐wide loss of their preferred facies. This enables consistent identification of the underlying extinction pattern for a wide variety of extinction scenarios. Applying this approach to empirical field data can help to constrain underlying extinction patterns from the fossil record.     

Ammonoid biostratigraphy of the Middle Triassic Latemar platform (Dolomites, Italy) and its correlation with Nevada and Canada

An extensive study of the ammonoid fauna occurring in the lagoonal facies of a Middle Triassic isolated carbonate platform (Latemar platform, Dolomites, Italy) has been undertaken, and ammonoids from selected coeval successions (Punta Zonia, Marmolada, Rio Sacuz) have been illustrated. Ammonoids from Latemar have been collected in 20 distinct horizons (storm deposits) within the ca. 500 m thick lagoonal succession of the platform, thus providing a biostratigraphy of a series which is unusually expanded for this time interval, close to the Anisian-Ladinian boundary. Contrary to general opinion, some ammonoids of the Latemar and other coeval carbonate platforms of the Dolomites (Marmolada, Cernera), in particular Aplococeras avisianum, Lecanites misanii, Celtites spp., and Paranevadites sp., are also present in nearby basinal series. The same taxa have been found in North American localities deposited at the opposite margin of Panthalassa. The homotaxis of these ammonoids in North America and Latemar allow to establish a global scale correlation between the Southern Alps and North America with the highest resolution to date possible. In the context of this study, Aplococeras transiens n. sp. and Esinoceras nerinae n. sp are established.     

The reefal margin and slope of a Middle Triassic carbonate platform: the Latemar (Dolomites, Italy)

The Latemar is a mainly aggrading platform, but shows repeated backstepping during its entire development. The behaviour of the slope does not reflect accommodation changes and lateral consistencies of the lagoonal interior; the Latemar contemporaneously reveals different, even contrasting depositional characteristics. The slope of the late stage platform evolution corresponds at least partially to the base-of-slope apron model. Controlling factors on slope evolution are of tectonic (proximity of the Stava Line) and autocyclic (repeated oversteepening) nature. Other factors are insignificant and/or overprinted. The reef-facies at Latemar reveals a complex facies pattern; it varies along and across the margin and is rich in encrusting sponges, corals, biogenic crusts and Microproblematica. Some biota or fossil assemblages—e.g. foraminifers (Abriolina mediterranea, Turriglomina scandonei) or Tubiphytes multisiphonatus thrombolites—have not been described in the Dolomites before. Biostratigraphic evidence from the uppermost reef-facies confirms a mainly Anisian age of the outcropping platform interior.     

Ammonite biostratigraphy of the uppermost Hauterivian in the Betic Cordillera (SE Spain)

A detailed analysis of the stratigraphic distribution of ammonites from fourteen sections in the External Zones of the Betic Cordillera has enabled us to identify accurately the sequence of bioevents that take place throughout the uppermost Hauterivian and to propose a more precise biostratigraphic scheme for this interval. Thus, we have divided the two currently admitted zones (the Crioceratites balearis Zone and the Pseudothurmannia angulicostata auct. Zone) into several subzones. Four subzones can be recognised within the Cr. balearis Zone. The base of each subzone is defined by the first occurrence of one of four successive species belonging to the same Crioceratites lineage. These species are: Cr. balearis, Cr. binelli, Cr. krenkeli and Cr. angulicostatus. The Ps. ohmi Zone (which replaces the classical Ps. angulicostata Zone) can be divided into three subzones characterised by three successive species of the genus Pseudothurmannia: Ps. ohmi, Ps mortilleti (here considered as a senior synonym of Ps. catulloi) and Ps. picteti. According to the current definition, the first occurrence of Taveraidiscus hugii (OOSTER) marks the lower boundary of the Barremian stage. This event fits into a major faunal-renewal episode that begins in the upper part of the Ps. picteti Subzone.     

New dasycladalean algae from the Middle Norian (Upper Triassic) of northern Italy (Mt. Pramaggiore, Carnic Prealps)

In the Eastern Southern Alps of northern Italy (Carnic Prealps, Friuli region), the shallow-water carbonate platform deposits of the Dolomia Principale Fm. (Norian–Rhaetian, Upper Triassic) show best-preserved platform to basin facies transition. The palaeontological study of an algal-rich level recovered from the platform margin facies (Mt. Pramaggiore) has displayed a very interesting association of Dasycladales. Two new genera (Bystrickyella and Elliottporella) and four new species (Bystrickyella ottii, Elliottporella morelloae, Palaeodasycladus lorigae and Holosporella conradii) have been described. These new data suggest that the Norian represents a period of turnover in the evolutionary history of the green algae community. This stage, placed between two extinctions, end-Ladinian and end-Norian, is here interpreted as a re-organization period of the evolutionary schemes of Dasycladales. The new lineages originated in the Norian developed further and characterized the Early Jurassic scenery. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

TIMING DEEP DIVERGENCE EVENTS IN CALCAREOUS DINOFLAGELLATES1

Based on morphological and molecular data, calcareous dinoflagellates (Thoracosphaeraceae, Peridiniales) are a monophyletic group comprising the three major clades Ensiculifera/Pentapharsodinium, Thoracosphaera/Pfiesteria, and Scrippsiella sensu lato. We used stratigraphically well‐documented first occurrences of particular archeopyle types to constrain relaxed Bayesian molecular clocks applied to nuclear rRNA sequences of 18 representatives of the three main clades. By comparing divergence estimates obtained in differently calibrated clocks with first stratigraphic occurrences of taxa not themselves used as constraints, we identified plausible divergence times for several subclades of calcareous dinoflagellates. The initial diversification of extant calcareous dinoflagellates probably took place in the Late Jurassic, with the three main clades all established by the Cretaceous. The two mesoepicystal operculum types observed in calcareous dinoflagellates probably evolved independently from simple apical archeopyles. Based on our taxon sample, the K/T boundary had relatively little effect on the diversity of the group, with several lineages dating to before 65 mya (million years ago). The first stratigraphic occurrences of key taxa, such as Thoracosphaera and Calciodinellum (not themselves used as constraints), are in agreement with the molecular time estimates. Conflicts that involve “Calciodinellum”levantinum, Leonella, Pentapharsodinium, Pernambugia, and the Scrippsiella trochoidea species complex may be due to inaccurate assignment of fossils because of high morphological homoplasy and insufficient knowledge of the extant diversity of calcareous dinoflagellates.     

Proposal for adoption of the base of the Undulograptus austrodentatus Biozone as a global Ordovician stage and series boundary level

The base of the Undulograptus austrodentatus Biozone appears to be a synchronous event that is widely recognizable within graptolitic facies around the world. It occurs within an interval in which graptolite species ranges are now well known and in which there is a rapid turnover in the composition of graptolite faunas. This turnover reflects the rapid evolutionary radiation of the Diplograptacea simultaneously with the appearance of several distinctive pseudisograptid and glossograptid species. These events provide the basis for the recognition of two thin but widely applicable subzones; a lower Arienigraptus zhejiangensis Subzone and an upper U. sinicus Subzone. The occurrence of the lower boundary of the U. austrodentatus Biozone within a succession of first appearances also permits accurate and reliable identification of the boundary as well as assessment of stratigraphic completeness across the boundary interval in correlated sections. Diverse graptolite faunas of late Yapeenian and early Darriwilian age occur in association with the Histiodella altifrons Biozone of the North American midcontinent conodont zonation and the Paroistodus originalis and Microzarkodina parva biozones of the North Atlantic conodont zonation. They also occur in association with the shelly-fossil zonations developed for several different continents. These features of the base of the U. austrodentatus Biozone make it a suitable level for use as the boundary level for a global stage. Its stratigraphic position within the Ordovician System relative to other likely global stages as well as its coincidence with one of the major events in graptolite evolutionary history suggest that this level also may be a suitable level for the base of a global Middle Ordovician Series.Ordovician System, Ordovician stages, graptolite zonation, chronostratigraphy, international correlation. Charles E. Mitchell and Jörg Maletz, Department of Geology, State University of New York at Buffalo, Buffalo, New York 14260-1550, USA; 13th July, 1994; revised 22nd May, 1995.     

Conodont chronostratigraphical resolution and Declinognathodus evolution close to the Mid‐Carboniferous Boundary in the Barcaliente Formation type section,NW Spain

The Barcaliente Formation in its type section provides significant conodont occurrences in the Mid‐Carboniferous Boundary interval (between the Mississippian and Pennsylvanian sub‐periods). A sequence of Declinognathodus morphotype appearances (considered here as species) is recognized from the uppermost Serpukhovian to the lower Bashkirian. These morphotypes belong to Declinognathodus noduliferus (Ellison & Graves) sensu lato, the primary marker for the worldwide correlation of the Mid‐Carboniferous Boundary. Among them, D. inaequalis (Higgins) appears to have been the first species to occur at the Mid‐Carboniferous Boundary bed in the Arrow Canyon GSSP. A morphocline between D. bernesgae (Sanz‐López et al.) and D. inaequalis is studied here to identify the bed correlated with the GSSP. Other diagnostic first occurrences of conodonts (Rachistognathus minutus (Higgins & Bouckaert), D. noduliferus, D. lateralis (Higgins & Bouckaert), Idiognathoides asiaticus Nigmadganov & Nemirovskaya and I. corrugatus (Harris & Hollingsworth)) are evaluated as chrono‐markers throughout their worldwide distribution, particularly for the Eurasian faunas. The available secondary markers provide a better resolution and support chrono‐correlation in sections other than that at the GSSP. The worldwide first and late occurrences of studied taxa are considered within the background of the Mid‐Carboniferous Extinction Event and the conodont overturn, where crises progenitor Declinognathodus gave rise to members of the Family Idiognathodontidae. Firstly, progenitor taxa are good biostratigraphic tools, whereas local extinction of genera considered Mississippian in age and new taxa arising later in the post‐crises radiation suggest an early Bashkirian palaeogeography and climatic conditions confining temporarily the biogeographic distribution of conodonts.     

Dynamics of East European modern amphibian and reptile species distribution areas and their potential use in Quaternary stratigraphy

The last appearance dates and especially occurrences of amphibian and reptile species have a rather limited stratigraphic potential in Quaternary deposits. However, changes in their areas of distribution against the background of climate variations open some possibilities for biostratigraphy. Based on fossil assemblages of amphibians and reptiles, interglacial or periglacial conditions can be distinguished. Substitution of forest associations by those typical for forest-steppes or steppes within the limits of the modern forest zone can be attributed to climate aridization at the onset of a glaciation. Therefore, during paleogeographic reconstructions, it is important to determine a natural zone, instead of an assortment of possible biotopes. Glacial intervals for modern steppe zones can theoretically be visualized by the emergence of desert taxa. Distribution areas of amphibians and reptiles during interglacial optima show different outlines. They usually varied slightly, but sometimes the range of some species expanded (Bufotes viridis) or species disappeared (Strauchbufo raddei) from a large part of their original distribution. Such changes can be used to define large age intervals within a regional biostratigraphy.     

Bioerosional structures and pseudoborings from Late Jurassic and Late Cretaceous-Paleocene shallow-water carbonates (Northern Calcareous Alps, Austria and SE France) with special reference to cryptobiotic foraminifera

Examples of bioerosional processes (boring patterns) are described from shallow-water limestones of the Late Jurassic Plassen Carbonate Platform (PCP) and the Late Cretaceous to Paleocene Gosau Group of the Northern Calcareous Alps, Austria. Some micro-/macro-borings can be related to distinct ichnotaxa, others are classified in open nomenclature. In the Alpine Late Jurassic, bioerosional structures recorded from clasts in mass-flows allow palaeogeographical conclusions concerning the source areas. In particular, these are borings of the Trypanites-ichnofacies detected from clasts (Barmstein limestones) of the PCP or special type of bored ooids of unknown source areas or restricted autochthonous occurrences. In the Lower Gosau Subgroup, Gastrochaenolites macroborings occur in mobile carbonate clast substrates of shore zone deposits (“Untersberg Marmor”). Different types of borings are recorded from rudist shells and coral skeleton, some of which are referable to the ichnotaxon Entobia produced by endolithic sponges. In the present study, special attention is paid to the occurrences of the cryptobiotic foraminifera Troglotella incrustans Wernli and Fookes in the Late Jurassic and Tauchella endolithica Cherchi and Schroeder in the Late Cretaceous. The latter is so far only known to be from the Early Cenomanian of France and is reported here for the first time from the Late Turonian-Early Coniacian stratigraphic interval where it was found in turbulent carbonate deposits within borings penetrating bivalve shells or coralline algae. The records of cryptobiotic foraminifera from the Northern Calcareous Alps are supplemented by a single finding from the Middle Cenomanian of SE France. A palaeoenvironmental interpretation of the occurrences of the cryptobiotic foraminifera is provided.     

Palaeoenvironmental significance of the green alga Botryococcus in the lacustrine rotliegend (upper carboniferous ‐ lower permian)

The green alga Botryococcus is an important component of the phytoplankton in lake sediments from the Rotliegend of Central Europe. The first microscopic fossils from the Saar‐Nahe Basin that can be assigned to this genus are described and illustrated here. Their distribution at various stratigraphic levels shows that the primary production of the lakes was at least partially controlled by these green algae. The frequency of fossils in the sediments is correlated with grain size, which varied with the depositional environment. Their abundance is greater in sediments deposited in shallow water, especially in small lakes and in the littoral environments of larger lakes. Sediments of deep‐water lake bottoms contain only minor amounts of algal remains. The abundance of kerogen originating from phytoplankton and occurrences of Botryococcus fossils are correlated in these lake deposits.     

PHYLOGENY OF THE DASYCLADALES (CHLOROPHYTA,ULVOPHYCEAE) BASED ON ANALYSES OF RUBISCO LARGE SUBUNIT (rbcL) GENE SEQUENCES1

The phylogeny of the green algal Order Dasycladales was inferred by maximum parsimony and Bayesian analyses of chloroplast‐encoded rbcL sequence data. Bayesian analysis suggested that the tribe Acetabularieae is monophyletic but that some genera within the tribe, such as Acetabularia Lamouroux and Polyphysa Lamouroux, are not. Bayesian analysis placed Halicoryne Harvey as the sister group of the Acetabularieae, a result consistent with limited fossil evidence and monophyly of the family Acetabulariaceae but was not supported by significant posterior probability. Bayesian analysis further suggested that the family Dasycladaceae is a paraphyletic assemblage at the base of the Dasycladales radiation, casting doubt on the current family‐level classification. The genus Cymopolia Lamouroux was inferred to be the basal‐most dasycladalean genus, which is also consistent with limited fossil evidence. Unweighted parsimony analyses provided similar results but primarily differed by the sister relationship between Halicoryne Lamouroux and Bornetella Munier‐Chalmas, thus supporting the monophyly of neither the families Acetabulariaceae nor Dasycladaceae. This result, however, was supported by low bootstrap values. Low transition‐to‐transversion ratios, potential loss of phylogenetic signal in third codon positions, and the 550 million year old Dasycladalean lineage suggest that dasyclad rbcL sequences may be saturated due to deep time divergences. Such factors may have contributed to inaccurate reconstruction of phylogeny, particularly with respect to potential inconsistency of parsimony analyses. Regardless, strongly negative g₁ values were obtained in analyses including all codon positions, indicating the presence of considerable phylogenetic signal in dasyclad rbcL sequence data. Morphological features relevant to the separation of taxa within the Dasycladales and the possible effects of extinction on phylogeny reconstruction are discussed relative to the inferred phylogenies.     

18S rDNA AND EVOLUTION IN THE DASYCLADALES (CHLOROPHYTA): MODERN LIVING FOSSILS1

Phylogenetic relationships were inferred from parsimony and distance analyses of nuclear small-subunit ribosomal DNA sequences taken from 14 species representing 8 of the 11 extant genera in the Dasycladales. Of 1733 aligned positions, 412 (23.8%) were variable and 251 (61%) of those were phylogenetically informative within the Dasycladales. Secondary structure was analyzed and taken into account during all phases of data analysis. Robustness of the trees was assessed using bootstrap analysis and g₁ statistics of tree-length decay. Strongly supported branches were robust to all methods of analysis regardless of weighting schemes used. The secondary structure of the 18S within the Dasycladales agrees with that of other green algae with the exception of a shared deletion in stemloop E10-1 (ca. 13 nucleotides long), which provides additional support for the uniqueness of this monophyletic group. A molecular clock was calibrated from the dasyclad fossil record and suggests a radiation of the Acetabulariaceae at 120 ± 30 million years (Ma) ago and the Dasycladaceae 215 ± 40 Ma ago. The split of the two lineages from a shared ancestor is estimated at 265 ± 50 Ma ago. Within the Dasycladaceae, Neomeris and Cymopolia are sister taxa, as are Batophora and Chlorocladus. Bornetella groups with the Neomeris and Cymopolia clade in 78% of the bootstrap replicates. Relationships among the Acetabulariaceae show that Acetabularia and Polyphysa do not form monophyletic groups as presently circumscribed. No evidence indicates that Acicularia is the oldest genus. Halicoryne, Chalmasia, and Dasycladus were not included in the analysis. Molecular data provide afresh background perspective from which to discuss the evolution of one of the most ancient lineages of green plants.     

4 Phylogeny of the dasycladales (ulvophyceae,chlorophyta) based on analyses of nuclear‐encoded large subunit rDNA

The Dasycladales is an ancient order of tropical benthic marine green algae, unique in their radially arranged unicellular thalli and well‐preserved fossil record due to extensive calcification of the thallus. The inference of an accurate phylogeny for the Dasycladales is important in order to better understand stratigraphy, character evolution, and classification. Previous analyses (rbcL and 18S rDNA) suggested that the Family Acetabulariaceae is monophyletic, but that the Family Dasycladaceae is a basal paraphyletic assemblage. However, the two data sets disagreed regarding genus‐ and species‐level relationships within the Dasycladales. For example, the placement of the genera, Halicoryne, Bornetella and Cymopolia were incongruent. Given the conflicting results of these previous analyses, the current project examined a third highly conserved nuclear‐encoded gene, 26S rDNA. Aligned 26S rDNA sequences were analyzed with parsimony and model‐based methods and compared to previous results based on18S and rbcL sequences. Family‐level relationships based on 26S rDNA were congruent with previous studies: the Acetabulariaceae is monophyletic while the Dasycladaceae is paraphyletic. In addition, acetabulariacean genera are not monophyletic, suggesting that the presence of a corona inferior or calcification of gametes may not be appropriate to define genera. Within the Dasycladaceae, the basal position of Cymopolia is supported by 26S rDNA, a result congruent with rbcL and stratigraphy but not with 18S data. These results will be discussed in the context of morphological character evolution, fossil stratigraphy and family, tribal and generic relationships among these living algal fossils. Supported in part by NSF grant DEB‐0128977 to FWZ.     

New data (smaller foraminifers and correlation with depositional sequences) on the Las Llacerias section (Late Pennsylvanian,Cantabrian Mountains,NW Spain)

New sedimentological and paleontological information on the uppermost Moscovian and Kasimovian strata of the Las Llacerias section, a succession exposed in the Picos de Europa region (Cantabrian Mountains) that is considered to bear interest for the global correlation of the Upper Pennsylvanian subsystem, are presented. Based on sedimentological studies, three stratigraphic intervals can be established which record three successive episodes in the evolution of the carbonate platform. The study of the environmental evolution and sea-level fluctuations, as well as biostratigraphic fusulinoidean information, allow the correlation of this section with the synorogenic deposits of the Gamonedo-Cabrales area (northern Picos de Europa region). It is recognized that in the Las Llacerias strata, 7 of the 11 depositional sequences of the latter area are represented. The taxonomy and distribution of smaller foraminifers, a fossil group never studied before in this section, have been analysed. Data obtained show the presence of, at least, 30 genera. In some cases (Syzrania aff. bulbosa, Tezaquina, Mesolasiodiscus, Pseudotaxis and Hemidiscus), their record in the Las Llacerias section significantly extends the stratigraphic genus or species range. The potential role of Protonodosaria and Nodosinelloides species, as well as the acme of Hemigordius schlumbergeri for the correlation of the Kasimovian deposits is reinforced within this study.     

PHYLOGENY OF THE ULVOPHYCEAE (CHLOROPHYTA): CLADISTIC ANALYSIS OF NUCLEAR-ENCODED rRNA SEQUENCE DATA1

Cladistic analysis of nuclear-encoded rRNA sequence data provided us with the basis for some new hypotheses of relationships within the green algal class Ulvophyceae. The orders Ulotrichales and Ulvales are separated from the clade formed by the remaining orders of siphonous and siphonocladous Ulvophyceae (Caulerpales, Siphonocladales /Cladophorales [S/C] complex, and the Dasycladales), by the Chlorophyceae and Pleurastrophyceae. Our results suggest that the Ulvophyceae is not a monophyletic group. Examination of inter- and intra-ordinal relationships within the siphonous and siphonocladous ulvophycean algae revealed that Cladophora, Chaetomorpha, Anadyomene, Microdictyon, Cladophoropsis and Dictyosphaeria form a clade. Thus the hypothesis, based on ultrastructural features, that the Siphonocladales and Cladophorales are closely related is supported. Also, the Caulerpales is a monophyletic group with two lineages; Caulerpa, Halimeda, and Udotea comprise one, and Bryopsis and Codium comprise the other. The Dasycladales (Cymopolia and Batophora) also forms a clade, but this clade is not inferred to be the sister group to the S/C complex as has been proposed. Instead, it is either the sister taxon to the Caulerpales or basal to the Caulerpales and S/C clade The Trentepohliales is also included at the base of the siphonous and siphonocladous ulvophycean clade. The Pleurastrophyceae, which, like the Ulvophyceae, posses a counter-clockwise arrangement of flagellar basal bodies, are more closely related to the Chlorophyceae than to the Ulvophyceae based on rRNA sequences. Thus, the arrangement of basal bodies does not diagnose a monophyletic group. Previously reported hypotheses of phylogenetic relationships of ulvophycean algae were tested. In each case, additional evolutionary steps were required to obtain the proposed relationships. Relationships of ulvophycean algae to other classes of green algae are discussed.     

Ecology of the pteridophytes on the southern slopes of Mt. Kilimanjaro – I. Altitudinal distribution

140 taxa of 61 genera in 24 families of pteridophytes were recorded on the southern slopes of Mt. Kilimanjaro. These represent about one third of the entire pteridophyte flora of Tanzania. The families richest in species are the Aspleniaceae, the Adiantaceae, the Dryopteridaceae, the Thelypteridaceae and the Hymenophyllaceae. Due to its luxuriant montane rain forest, which receives a precipitation of up to over 3000 mm, Mt. Kilimanjaro is distinctly richer in pteridophyte species than other volcanoes in East Africa. However, compared with the mountains of the Eastern Arc, the number of pteridophytes on Mt. Kilimanjaro is smaller. This can be explained by the widely destroyed submontane (intermediate) forest rather than by the higher age of the Eastern Arc Mts.The altitudinal distribution of all ferns was investigated in 24 transects. On the southern slopes of Mt. Kilimanjaro they were found in an altitudinal range of 3640 m. Cyclosorus quadrangularis, Azolla nilotica, Azolla africana andMarsilea minuta are restricted to the foothills, while Polystichum wilsonii, Cystopteris nivalis and Asplenium adiantum-nigrum are species found in the highest altitudes.Based on unidimensionally constrained clustering and on the analysis of the lowermost and uppermost occurrence of species, floristic discontinuities within the transects were determined. From these data and from an evaluation of the distribution of ecological groups and life forms, 11 altitudinal zones could be distinguished: a colline zone (–900 m asl), a submontane zone (900–1600 m asl) with lower and upper subzones, a montane zone (1600-2800 m asl) divided into 4 subzones, a subalpine zone (2800–3900 m asl) with lower, middle and upper subzones, and finally a (lower) alpine zone above 3900 m. The highest species numbers were observed in the lower montane forest belt between 1600 and 2000 m altitude. The zonation of ferns found at Mt. Kilimanjaro corresponds well with the vegetational zonation described by other authors using bryophytes as indicators in different parts of the humid tropics.     

A survey of species assigned to the fossil pollen genus Anacolosidites

Anacolosidites Cookson & Pike, a fossil pollen genus recorded since the Campanian, is peculiar in its morphology – six‐porate with three apertures on each hemisphere, located away from the equator, and with the distal and proximal apertures positioned over each other. Representatives of this fossil genus are widely considered to represent extant Olacaceae from tribe Anacoloseae. Olacaceae is an exclusively tropical angiosperm family with a pantropical distribution; consequently the fossils are often used to suggest a tropical climate and in addition are frequently used as a stratigraphic marker. Fossil species assigned to Anacolosidites are quite variable and may not all represent Olacaceae, in which case they may not indicate tropical climate.

The present study is a morphological survey of fossil pollen assigned to Anacolosidites; it identifies the published reports of the fossil species that probably represent positive occurrences of Olacaceae pollen in the fossil record. Within Olacaceae, Anacolosidites‐type pollen is usually compared with pollen of genera in tribe Anacoloseae, in particular: Cathedra, Anacolosa and Phanerodiscus, but never with the pollen of Ptychopetalum, a genus from tribe Olaceae with closely similar pollen to the other three genera, but with a reticulate tectum and very small circular apertures located near the equator. Nevertheless, the records of reticulate Anacolosidites species which have been excluded from the emended diagnosis are unlikely to be related to Ptychopetalum. The earliest accepted record of Anacolosidites is from the Late Cretaceous (Maastrichtian) of Germany. However, most Late Cretaceous records, and later Russian and Chinese occurrences referred to Anacolosidites, consist mainly of Normapolles‐type pollen, whereas many of the Cenozoic records assigned to Anacolosidites have a much clearer affinity with the pollen of Anacolosa, Cathedra and Phanerodiscus (tribe Anacoloseae). The newly emended genus Anacolosidites may be used as a stratigraphic marker for tropical or megathermal climatic conditions.     

Spatial distribution patterns of Rhynchostegium megapolitanum at the landscape scale ‐ an expanding species?

Question: Is Rhynchostegium megapolitanum an expanding species? Location: Viennese Basin (120‐220 m a.s.1.), Austria. Methods: 121 dry grasslands, were investigated for the occurrence of R. megapolitanum. Nineteen environmental variables at 50 randomly selected sites, species composition at sites with and without R. megapolitanum and the spatial patterns of distribution of the species at the landscape scale were analysed. We compared actual distribution data of three rare species (Didymodon acutus, Pleurochaete squarrosa R. megapolitanum) and a common one (Brachythecium rutabulum) with the distribution obtained by vouchers that were collected between 1860 and 1940 in the investigated area. We calculated a GIS based model pattern and compared it with the actual distribution. Results: R. megapolitanum was detected in 28 of these sites, almost 50 % of its populations produced sporophytes. We found significant differences between sites with and without R. megapolitanum with regard to grassland size, the percentage of silt and of sand in the soil. There were fewer occurrences of historic herbarium vouchers of R. megapolitanum than our current field survey discovered. The GIS based analyses of distribution patterns at the landscape scale showed a clustering of sites in which R. megapolitanum was present or absent. Simulations with a spatially realistic expansion model showed high similarities to the actual distribution of the species. Conclusions: All these analyses suggest that R. megapolitanum has been expanding in the investigated area. A significant increase in temperature and nitrogen deposition within the last hundred years might be the underlying cause for the species' spread.     

Predicting the distribution of a novel bark beetle and its pine hosts under future climate conditions

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