Oppel Zone Research Articles

An earliest Triassic riparian ecosystem from the Bulgo Sandstone (Sydney Basin), Australia: palynofloral evidence of a high-latitude terrestrial vertebrate habitat after the end-Permian mass extinction

A landmark change in terrestrial ecosystems took place after the end-Permian mass extinction (EPME). This was marked by disappearance of the iconic latest Permian Glossopteris forests in Australian continental successions dated to 252.10 ± 0.06 Ma (mega-annum). Pioneering earliest Triassic spore-producing plants then spread following catastrophic wildfires, soil erosion and algal blooms. These ruderal plant communities were later replaced by vast Dicroidium ‘seed fern’ forests, which established under warm, seasonally dry conditions. By contrast, evidence of coeval vertebrate assemblages is scarce in Australia. The Bulgo Sandstone (Narrabeen Group) fossil biota in the Sydney Basin is, therefore, important as a rare example of associated plant and animal communities from the Early Triassic. The fossils include imprints and organic remains of lycopsid roots and attributed leaves (microphylls), Dicroidium and Lepidopteris foliage, and both erythrosuchid and smaller-bodied archosauromorphs, capitosaurians and other temnospondyls, actinopterygian fishes and sharks. Here, we undertake a palynofloral analysis of the vertebrate fossil-bearing bed within the Bulgo Sandstone to determine the assemblage age and palaeoenvironment. We identified a low-diversity miospore suite that is overwhelmingly dominated by lycopsids (42%), and especially quillworts (Isoëtales/Pleuromeiales) represented by Densoisporites and Aratrisporites. Bryophyte (moss), sphenopsid (horsetail) and ground fern spores are also present. Pollen (14%) comprises forms mainly associated with voltzialean conifers. The non-taeniate bisaccate Falcisporites (Alisporites) produced by Dicroidium is comparatively rare (3%). Based on this taxic composition, we correlate the vertebrate-bearing layer of the Bulgo Sandstone with the lower part of the Protohaploxypinus samoilovichii Oppel Zone and suggest a late Induan to early Olenekian age. Calculated sedimentation rates indicate that the 400 m of sediments between the top of the Vales Point Coal and the base of the Bulgo Sandstone were laid down within a time span of 40–400 ka (kilo-annum). Furthermore, the high portion of spores (37%) implies a parautochthonous organic accumulation that would have derived from local vegetation. This was likely riparian, with Dicroidium (and associated gymnosperm) cuticles (ca 20%) being over-represented because of a deciduous seasonal cycle. Notably, the Bulgo Sandstone accumulated on a high-palaeolatitude floodplain (ca 66–69°S) with dense vegetation flanking waterways that might have provided both shelter and forage for terrestrial vertebrates living less than 1 Ma after the EPME ecosystem collapse. Vivi Vajda* [vivi.vajda@nrm.se], Swedish Museum of Natural History, Svante Arrhenius väg 9, Stockholm 11414, Sweden; Benjamin P. Kear [benjamin.kear@em.uu.se], The Museum of Evolution, Uppsala University, Norbyvägen 16, Uppsala 75236, Sweden.

Palynological assemblages from Hongguleleng Formation of Western Junggar, Northwest China and their correlation with conodont zonation

The Upper Devonian Hongguleleng Formation is a significant stratigraphic unit near the Frasnian/Famennian and Devonian/Carboniferous boundaries of the Kazakhstan Paleoplate. However, its age is still under debate. A new palynostratigraphic analysis was conducted at the Gennaren section to provide a more accurate biostratigraphic assignment. In this study, we identified 43 species belonging to 26 spore genera, including those in open nomenclature. Despite the poor preservation of the palynofloras, the spore taxa were categorized into two assemblages. Assemblage I is established at the lower part of the lower member of the Hongguleleng Formation, containing Cornispora varicornata, cf. Auroraspora pseudocrista, and Cyrtospora cristifera. Assemblage II is from the upper part of the lower member of the Hongguleleng Formation, including Grandispora cornuta, Grandispora famennensis var. famennensis, Grandispora cf. famennensis var. minutus, Grandispora microseta, and Rugospora radiata. These assemblages are compared with the Western European DV Oppel Zone (lower-middle Famennian), and the GF to VCo Oppel zones. The assemblages are equivalent to the conodont crepida–rhomboidea and marginifera to Lower trachytera zones (middle-upper Famennian).

Updating Frasnian miospore zonation from the Boulonnais (Northern France) and comparison with new data from the Upper Palaeozoic cover on the Brabant Massif (Western Belgium)

Accurate palyno-analysis by S. Loboziak (from 1980 to 1983) of 28 samples from the Upper Givetian to the Middle Frasnian Blacourt, Beaulieu and Ferques Formations and of 44 samples of the Upper Frasnian to the Lower Famennian Hydrequent Formation are re-evaluated. Chelinospora concinna, Verrucosisporites bulliferus, Cirratriradites jekhowskyi, Lophozonotriletes media first occurrences are major criteria for Lower and Middle Frasnian, well calibrated by conodonts. Cymbosporites acanthaceus, Rugospora bricei, Grandispora gracilis, Diducites plicabilis, Corbulispora vimineus first occurrences allow to subdivide the Upper Frasnian where conodonts are poorly present. Samarisporites triangulatus versus Auroraspora pseudocrista taxonomy and stratigraphic significance are discussed. The reconnaissance borehole Nieuwkerke-De Seule (95W152), near the limit of the Upper Palaeozoic subcrop on the Brabant Massif (West Flanders, Belgium, 75 km east of the Boulonnais), which has intersected conodont-dated Givetian/Frasnian boundary at the transition between the Bois de Bordeaux and Bovesse Formations, contained poorly preserved miospores attributed to the triangulatus–concinna (TCo) Oppel Zones. In the nearby Nieuwkerke-Noordhoek borehole (95W153), strata also assigned to the Bovesse Formation yielded better preserved miospores which demonstrate a close succession of triangulatus–concinna (TCo) and bulliferus–jekhowskyi (BJ) Oppel Zones at the transition Lower–Middle Frasnian, also known in the Beaulieu Formation in the Boulonnais. Samples from the Heuvelland groundwater monitoring well (95W175), 10 km north of Nieuwkerke, contain the bricei-acanthaceus (BA) Oppel Zone suggesting a late Frasnian age, also known in the Hydrequent Formation in the Boulonnais area and in the Booischot Formation in the Booischot borehole (59E146) from the Campine Basin (Belgium). International correlation using Frasnian miospore zonation is attempted between the Pripyat Depression in Belarus, the Timan–Pechora province in Russia and North-West China.

The Unitary Association method in biochronology and its potential stratigraphic power between benthic and planktic organisms: A case study on foraminifers from Paleocene–Eocene strata of southern Egypt

Although foraminifers have been extensively used for biochronology, no quantitative evaluation of the quality of their application is available. In this work we apply a quantitative approach – the Unitary Association (UA) method – to evaluate the relative quality of planktic and benthic foraminifers in biostratigraphy. Based on 12,321 specimens belonging to 65 planktic and 132 benthic foraminifer species in 117 samples from the Paleocene–Eocene strata of the Kharga-Baris Oases (Western Desert, Egypt), the potential stratigraphic resolution power of benthic foraminifers is quantitatively assessed and compared to planktic foraminifers. The UA method accounts for superpositional contradictions between sets of coexisting taxa and generates unitary associations, which are conceptually similar to Oppel zones. The analysis produced fifteen unitary associations for the Paleocene–Eocene benthic Foraminifera of the studied sections, instead of three classical zones; most of these unitary associations are easily identified by the restricted occurrence of a single species. Although planktic Foraminifera have a higher seriation reality leading to a more robust biozonation, benthic Foraminifera have a higher stratigraphic resolution, at least at such regional scale. Furthermore, there was a significant positive correlation between the number of unitary associations and the number of species (R=0.78 for planktic and 0.70 for benthic foraminifers; both with p<0.001). These results corroborate that quantitative techniques may lead to a higher resolution in biochronology, even when applied to poor biochronological markers. Moreover, in contrast to simple spatiotemporal analyses, the Unitary Association method can accurately assess the stratigraphic potential of a given taxonomic group.

Revisiting the spore assemblages from the Lower Devonian Posongchong Formation of Wenshan, Yunnan Province, southwestern China

ABSTRACTThe Lower Devonian Posongchong Formation (Wenshan, Yunnan Province, southwestern China) consists of a series of continental deposits with an outstanding plant megafossil diversity. More than 20 years ago, this formation was interpreted as ‘Siegenian' (∼Pragian) in age based on palynology. However, such interpretation needs further evidence because of the known differences between the dispersed spore assemblages from South China and Euramerica/northwestern Gondwana. Here, we present new dispersed spore assemblages recently recovered from the Posongchong Formation. The isolated spore diversity is highly diverse, with 18 genera and 32 species. The recognised taxa include, among others, Ambitisporites avitus, Aneurospora conica, Aneurospora posongchongensis sp. nov., Aneurospora xujiachongensis, Apiculiretusispora plicata, Archaeozonotriletes chulus, Concentricosisporites agradabilis, Dibolisporites echinaceus, Emphanisporites rotatus, Gneudnaspora divellomedia, Latosporites ovalis, Retusotriletes triangulatus, Tetrahedraletes medinensis and Verrucosporites polygonalis, with Aneurospora and Retusotriletes being the most abundant forms. The known Posongchong palynoflora (previous spore data included) suggests that the Posongchong Formation assemblages can be correlated with the Pragian interval of the polygonalis–wetteldorfensis Oppel Zone (PoW). This age determination is supported by the presence of index species of PoW, such as Verrucosporites polygonalis, Dictyotriletes subgranifer and Camarozonotriletes parvus (sensu Steemans, 1989), the latter being known only from the Pragian of Belgium and Germany. Recent advances in the study of the marine faunas in the overlying sequences also indicate a Pragian age for the Posongchong Formation. This new investigation of the Posongchong palynoflora highlights differences of abundance at species level between the Gondwanan–Laurussian floras during the Early Devonian.

The Contribution of Fossils to Chronostratigraphy, 150 Years after Albert Oppel

The 150th anniversary of the death of Albert Oppel (1831–65) provided the opportunity to celebrate this outstanding stratigrapher with a Thematic Issue dedicated to the importance of fossils for dating and correlating of sedimentary rocks. In this issue, we analyse Oppel's significant contribution to modern chronostratigraphy, before exploring the Phanerozoic through all its major fossil groups, to verify if fossils are still able to make a significant contribution to chronostratigraphy. The extraordinary merit of Oppel's work has been the demonstration that fossils can be used to sub-divide sedimentary sequences into zones, which in turn might be organized in higher chronostratigraphical units. The zone for Oppel is characterized by the distinctive fossil content, and his view strongly influenced the development of the standard chronostratigraphical scale for about one century, until the introduction, in the 1950s, of the log-based range chart as the common practice to study the fossil record of sedimentary successions. This approach forced the stratigraphers to shift the focus from the fossil content of the zones to their boundaries. This new view allowed for the introduction of new kind of zones with precisely defined boundaries based on bioevents and to the decline of the Oppel Zone. This turning point in the history of chronostratigraphy was fuelled by the International Commission on Stratigraphy programme of definition of the units of the International Chronostratigraphic Chart based on the boundary stratotype and point (GSSP) concept, which started in 1973.

The evolution of Oppel's ‘Macrocephalusbett’ (Callovian, Middle Jurassic)

In his basic work of 1856–1858, Albert Oppel subdivided his ‘Juraformation’ into eight stages and 32 zones. There is a long history of confusion as to the meaning of Oppel's zones. Using his ‘Macrocephalusbett’ and his ‘Zone des Amm. macrocephalus’, it is explained how his concept has been developed until today. Both and also Oppel's ‘Macrocephalus Schichten’ are chronostratigraphical units and correspond to today's Lower Callovian. The Lower Callovian was first subdivided by Buckman and Spath into three zones: Herveyi, Koenigi and Calloviense. These units hold good for the Subboreal Province in Central Europe and England and became the primary standard. In addition, there are four more secondary standard zonations in other faunal provinces. In terms of the ammonites, the amount and quality of material available improved and also the methods used to assess morphological similarities. That makes a finer resolution possible, and today, the Lower Callovian of England and Central Europe consists of eight subzones with about 20 biohorizons.

Spore assemblages from the Lower Devonian ‘Lower Old Red Sandstone’ deposits of the Northern Highlands of Scotland: the Berriedale Outlier

ABSTRACTAssemblages of well-preserved dispersed spores have been recovered from the ‘Lower Old Red Sandstone’ deposits of the Berriedale Outlier in the Northern Highlands of Scotland. They belong to the annulatus–sextantii Spore Assemblage Biozone (AS SAB), in the spore zonation of Richardson &amp; McGregor (1986), indicating an Early Devonian Emsian (but not earliest Emsian or latest Emsian) age. Comparison with the spore zonation of Streel et al. (1987) suggests they may be confined to the annulatus–bellatulus Oppel Zone (AB OZ), further constraining the age to early Emsian. This new biostratigraphical datum provides an age constraint for the onset of ‘Lower Old Red Sandstone’ sedimentation in the Orcadian Basin and, in particular, northwest of the Great Glen Fault System on the Northern Highlands. In the Orcadian Basin, there is a gap between ‘Lower Old Red Sandstone’ and ‘Middle Old Red Sandstone’ sedimentation, represented by either unconformity or disconformity, which appears to be variable in duration. In the Berriedale Outlier, it is estimated to represent up to 16 million years, but with an unknown thickness of ‘Lower Old Red Sandstone’ sequence removed at the unconformity. However, this basin-wide unconformity/disconformity is likely due to minor, local rather than large-scale, regional tectonism, and the evidence suggests little, if any, syn-depositional strike-slip movement along the Great Glen Fault System during Devonian ‘Old Red Sandstone’ deposition. The described spore assemblage is the most diverse AS SAB/AB OZ assemblage described from the British Isles. However, compared to contemporary spore assemblages from elsewhere on the Old Red Sandstone continent, the Scottish material is rather depauperate, with certain key taxa absent. This probably reflects subtle ecological effects, with the Scottish material representing restricted floras of the inland intermontaine basins.

An early Devonian age for the Bulls Head Formation, Lower Old Red Sandstone, Dingle Peninsula

The Bulls Head Formation is the oldest lithostratigraphic formation in the 2.8km thick Dingle Group (Lower Old Red Sandstone) succession of the Dingle Peninsula. The formation mainly comprises thinly bedded, fine-grained purple-grey sandstones interlaminated with thin mudstone layers (Heterolithic Member) that were deposited in a very extensive shallow lake, here named ‘Lake Blasket’. The formation also includes two lake margin sheetflood systems (the Boat Cove and Trabane Members) that are only developed on the northern lake limit. The Bulls Head Formation has been previously assigned a late Silurian (late Ludlow-Pridoli) age. Two spore assemblages obtained from the Trabane Member are assigned to Z Interval Zone of the Breconisporites breconensis and Emphanisporites zavallatus BZ Oppel Zone, which indicates the upper part of the Bulls Head Formation is early Devonian (late Lockhovian) in age. In addition, a small disarticulated fish plate is recorded from the matrix of a mudclast conglomerate of the Trabane Member and this represents the first body fossil ever to be found in the Dingle Group. The plate is assignable to the Heterostraci group of jawless fish that were common in late Silurian and early Devonian times. A new palaeoenvironmental model for the Trabane Member proposes fluctuating lake levels and periodic fluvial sheetfloods with contemporaneous erosion.

Evolution of the Paleocene-Early Eocene larger benthic foraminifera in the Tethyan Himalaya of Tibet, China

The Paleocene-Early Eocene larger benthic foraminifera (LBF) in the far eastern Neo-Tethyan Ocean of Tibet still remain poorly known. Here, we present a novel, high-resolution larger foraminiferal biozonation from the shallow-water limestones in Tibet, which will improve our current understanding of the larger foraminiferal evolution in the eastern Neo-Tethyan Ocean. Based on one continuous section at Tingri and three separate sections at Gamba, ten Shallow Benthic Zones (SBZ 1–10) have been designated in Tibet by following the principle of Oppel Zone. In contrast to those in Europe, the Paleocene LBFs in Tibet are characterized by high diversification of Lockhartia, Kathina, Daviesina, Miscellanea, Ranikothalia, and Operculina and show progressively increasing diversity of genera and species during SBZ 2–5. Adult dimorphism and large shell size of some LBFs as well as differentiation of the diversity between genera and species initiated as early as SBZ 3. It suggests that the occurrence of the Larger Foraminifera Turnover (LFT) was probably not synchronous in the entire Neo-Tethyan Ocean, because in Europe, the LFT was generally thought to occur at the beginning of SBZ 5. During the Early Eocene, the LBFs in Tibet decreased markedly on the generic level and increased on the species level, and some new genera (Alveolina, Orbitolites, Nummulites, Assilina, Discocyclina) have gained predominance in Tibet. It is nearly identical to the evolution of the LBFs in Europe and indicates a high-degree homogenization of the LBFs in the entire Neo-Tethyan Ocean. Furthermore, the Paleocene-Eocene (P-E) boundary in shallow-water environments has been clearly identified by us, and it is situated in the upper part of SBZ 5 and associated with no evident biotic turnover of shallow benthic foraminiferal communities. The possible diachroneity of the LFT in the Neo-Tethyan Ocean and the evident lagging of the Paleocene-Eocene Thermal Maximum (PETM) behind the LFT imply that the LFT could only be the result of a natural evolutionary process and has no linkage with the PETM. Notably, a transient but distinct larger foraminiferal extinction and origination (LFEO) event has been found in Tibet, which is characterized by a sudden disappearance of all Paleocene lamellar-perforate LBFs, such as Lockhartia, Kathina, Daviesina, Miscellanea, Ranikothalia, and Operculina, and the initial dominance of the Early Eocene porcellaneous-walled Alveolina. The LFEO marks the boundary between SBZ 5 and 6, and might only occur in the low-latitude areas of the Neo-Tethyan Ocean. Surprisingly, the LFEO coincides with the initial recovery of the Carbon Isotope Excursion (CIE), and their synchronicity implies that some possible mechanisms causing the rapid recovery of the CIE probably had also led to the LFEO in the shallow-water environments.

Diverse assemblages of Mid Devonian megaspores from Libya

A restudy of Devonian palynological assemblages of samples from the A1-69 borehole, drilled in the Ghadamis Basin, western Libya, North Africa has led to the discovery of numerous well-preserved megaspores amongst abundant miospores, rare acritarchs and rare chitinozoans. Thirteen samples from base to top, 1496 ft (456 m) up to 965 ft (294 m), contain the richest Devonian megaspore assemblages from northwestern Gondwana. The section is dated by a rich diverse miospore assemblage indicating the presence of the upper part of the AD pre-Lem Biozone up to the lower part of the TCo Oppel Zone, ranging from a latest Eifelian or earliest Givetian age up to a latest Givetian or an earliest Frasnian age. Seventeen megaspore taxa have been identified. Among them, two new species ( Biharisporites lugardonii and Lagenicula milleri) and four new varieties ( Corystisporites acutispinosus var. acutispinosus and var. bullatus, Heliotriletes longispinosus var. longispinosus and var. radiatus) are described. One new possible megaspore species is also described: Verruciretusispora labiosa sp. nov. One core sample (1293 ft, 394 m) contains several specimens of very large megaspores (ca. 1 mm), the largest known from Devonian localities (except for one specimen observed in the Givetian from Belgium). Among the 17 megaspore taxa from Libya, 6 are present on the Euramerican Continent. This observation is in accordance with previous palynological conclusions that favour the absence of palaeogeographic barriers between the Euramerican and Gondwanan continents that are suggested to be grouped together in a “Pre-Pangea” land mass.

New evidence for the age of the Athol Formation (Middle Jurassic; Bajocian) in the Tusk-1 and Tusk-2 wells, offshore Carnarvon Basin, Western Australia

The co-occurrence of ammonites with palynomorphs in the Athol Formation of the Tusk-1 and Tusk-2 wells drilled in the offshore Carnarvon Basin, Western Australia confirms the Early Bajocian (Middle Jurassic) age of the Dissiliodinium caddaense dinoflagellate cyst Oppel Zone. The macrofaunas refine this Early Bajocian age to the early Laeviuscula Chronozone. A belemnite from the Tusk-1 well has a strontium isotope (87Sr/86Sr) ratio consistent with the biostratigraphical age. All the identifiable ammonites belong to Pseudotoites robiginosus (Crick). Pseudotoites is prominent in the Early Bajocian of the Indo-Pacific Realm, being known mainly from onshore Western Australia and the Southern Andes, together with rare occurrences in Irian Jaya (west New Guinea); somewhat surprisingly, it is also rarely present in southern Alaska. The palynofloras studied from the Tusk-1 and Tusk-2 wells contain abundant specimens of the marine dinoflagellate cyst Dissiliodinium caddaense, and are assigned to the Dissiliodinium caddaense Oppel Zone. The Athol Formation is a correlative of the Newmarracarra Limestone of the onshore Perth Basin, Western Australia; the distribution of both these units indicates a marine transgression onto the Australian block during the Early Bajocian.

The age of the carboniferous‐Permian Converrucosisporites confluens Oppel biozone: New data from the Ganigobis shale member (DWYKA group) of Namibia

The establishment of the Converrucosisporites confluens Oppel Zone in the Canning Basin of Australia in cored intervals from the Calytrix No. 1 Borehole was considered to be an advance in Gondwana Carboniferous‐Permian palynostratigraphy. This was because the zone is associated with a marine fauna that suggests a correlation with the standard Russian Early Permian stages. Moreover the index species has a wide occurrence in Gondwana outside Australia, for example Antarctica, Argentina, Brazil, India, Oman, Saudi Arabia, and Uruguay. The zone was originally considered middle to late Asselian in age, but this was later revised to latest Asselian to Early Sakmarian. Converrucosisporites confluens is reported here from the Ganigobis Shale Member of Namibia in a well‐preserved and diverse assemblage including four of the fourteen specified accessory taxa for the Converrucosisporites confluens Oppel Zone. Ash layer IIb of the Ganigobis Shale Member is radiometrically dated as 302.0 ±3.0 Ma (i.e. Pennsylvanian; Gzhelian or Kasimovian) thus the Converrucosisporites confluens Oppel Zone may range earlier than previously thought. Preliminary study of the range top of Converrucosisporites confluens in Argentina and Uruguay suggests that it ranges younger there than in Western Australia with the possibility that the Converrucosisporites confluens Oppel Zone may also be younger than previously thought.

THE AGE OF THE CARBONIFEROUS-PERMIAN CONVERRUCOSISPORITES CONFLUENS OPPEL BIOZONE: NEW DATA FROM THE GANIGOBIS SHALE MEMBER (DWYKA GROUP) OF NAMIBIA

Abstract The establishment of the Converrucosisporites confluens Oppel Zone in the Canning Basin of Australia in cored intervals from the Calytrix No. 1 Borehole was considered to be an advance in Gondwana Carboniferous—Permian palynostratigraphy. This was because the zone is associated with a marine fauna that suggests a correlation with the standard Russian Early Permian stages. Moreover the index species has a wide occurrence in Gondwana outside Australia, for example Antarctica, Argentina, Brazil, India, Oman, Saudi Arabia, and Uruguay. The zone was originally considered middle to late Asselian in age, but this was later revised to latest Asselian to Early Sakmarian. Converrucosisporites confluens is reported here from the Ganigobis Shale Member of Namibia in a well-preserved and diverse assemblage including four of the fourteen specified accessory taxa for the Converrucosisporites confluens Oppel Zone. Ash layer IIb of the Ganigobis Shale Member is radiometrically dated as 302.0 ±3.0 Ma (i.e. Pennsyl...

Palynostratigraphy from the Lower devonian of the Paraná Basin, South Brazil, and a revision of contemporary chitinozoan biozones from Western Gondwana

New palynomorph data from the Paraná Basin, south Brazil, suggests a discontinuous sedimentation during the Lower Devonian. A comparison is made with coeval beds in Argentina, Bolivia and other intracratonic basins from Brazil. The Lochkovian/Pragian boundary is best developed in Bolivia and is distinguished by the first appearance of Ramochitina magnifica Lange 1967, which succeeds characteristic late Lochkovian chitinozoan species from underlying strata (e.g. Angochitina filosa Eisenack 1959, Cingulochitina ervensis Paris 1979, Cingulochitina serrata Taugourdeau and Jekhowsky 1960, Ramochitina jutaiense Grahn et al. 2003, and Urochitina loboi Volkheimer et al. 1986). Based on spore evidence, the Urochitina loboi Zone is considered as a subzone in the upper late Lochkovian part of the Angochitina strigosa Zone. A palynomorphic barren interval, corresponding to most of the Pragian (PoW, pre-Su spore Interval Zone of Streel et al. 1987), occurs in Western Gondwana. No positive evidence is present for rocks coeval with the Emsian AB and FD spore Oppel Zones of Streel et al. (1987). Ancyrochitina biconstricta (Lange 1949) is a characteristic Emsian species, and not conspecific with Cladochitina biconstricta Lange 1949 sensu Quadros 1982, which is a new late Eifelian – late early Givetian species. Ramochitina praemagnifica and Spinachitina aciculata, are described as new species.

Robert M. Kleinpell: Founder of the Berkeley School of Stratigraphic Paleontology

Robert M. Kleinpell (1905-1986) has been called the founder of a ‘Berkeley School of West Coast Cenozoic Stratigraphic Paleontology’. Through his personal experiences in carrying out oil exploration in California's Cenozoic stratigraphic successions, his extensive inquiry into the fundamentals of stratigraphic paleontology, and his teaching activity while held in a Japanese prison camp during World War II, Kleinpell developed the basic ingredients for his school of stratigraphic paleontology. His school attracted numbers of students interested in obtaining employment in the oil industry when Kleinpell joined the Department of Paleontology at University of California, Berkeley, in 1953. Kleinpell told his students that the first step toward a basic understanding of stratigraphic geology came from field mapping and recording of all relevant data. The data included collecting fossils from precisely-positioned stratigraphic levels. The fossil occurrence information was then plotted carefully to ascertain associations of taxa that appeared to be unique. The associations that appeared to be unique in time, based on their stratigraphic positions (Kleinpell came to term these ‘congregations’), were used to recognize zones and stages. Kleinpell was firm in his conviction that the zones and stages that he and his students recognized in American West Coast Cenozoic strata were closely similar in principle to the zones and Zonengruppe of Albert Oppel who had worked with ammonite faunas in the European Jurassic. Kleinpell did not publish a diagram or definition of the zones that he espoused because, he said, Oppel had already defined that type of zone. Hollis Hedberg, Kleinpell's former fellow-student in graduate study at Stanford, did include a discussion of the ‘zone’ of Oppel and Kleinpell in the 1976 International Stratigraphic Guide. Subsequent international and American stratigraphic guides and codes have omitted Hedberg's discussion and illustration of the Oppel zone. The West Coast Cenozoic zones and stages, recognized using the methodology established by Oppel, are a primary characteristic of the Berkeley School of Stratigraphic Paleontology.

New evidence for the Early Devonian age of the Jauf Formation in northern Saudi Arabia

Well-preserved Early Devonian continental and sparse marine palynomorph assemblages recovered from an exploration borehole located in northern Saudi Arabia are reported here and add to the understanding of Arabian Devonian stratigraphy. The units examined are the conventionally cored lower Murayr, upper Hammamiyat and Sha’iba Members of the Jauf Formation. A comparison with data sets from elsewhere on the Arabian Plate suggests that the units examined are Emsian in age. The age of the Murayr and Hammamiyat boundary interval is revised, based on the occurrence of Dibolisporites eifeliensis in northern Saudi Arabia, and placed in the Rhabdosporites minutus (Min) Interval Zone of the Emphanisporites foveolatus- Verrucosisporites dubia (FD) Oppel Zone. A new miospore, Apiculiretusispora densa with distinctive interradial thickenings, is described.

Spore assemblages from the Lower Devonian ‘Lower Old Red Sandstone’ deposits of the Rhynie outlier, Scotland

ABSTRACTSince the late 1980s an extensive programme of trenching/borehole drilling has been undertaken in order to study the Lower Devonian ‘Lower Old Red Sandstone’ deposits of the Rhynie outlier in the Grampian Highlands of Scotland. The boreholes have provided new information on the stratigraphical succession and geological structure of the Rhynie outlier, both of which were hitherto poorly understood due to the paucity of good surface exposure and the complex geological relationships of the deposits. One hundred and eighteen palynological samples were collected, representing much of the stratigraphical sequence of the inlier, of which 106 were productive. Productive samples yield assemblages of well preserved palynomorphs, dominated by spores and phytodebris, but also containing arthropod cuticle and rare freshwater algal remains. The spore assemblages are systematically described and two new genera and six new species proposed. They are similar throughout the sequence and the spores belong to the polygonalis–emsiensis Spore Assemblage Biozone of Richardson &amp; McGregor (1986) and the PoW Oppel Zone (possibly Su Interval Zone) of Streel et al. (1987), indicating an early (but not earliest) Pragian–?earliest Emsian age range, that may possibly be restricted to latest Pragian–?earliest Emsian. The palynomorph assemblages contain only terrestrial forms, supporting sedimentological interpretation of the deposits as ‘Lower Old Red Sandstone’ fluviatile and lacustrine deposits, with occasional extrusive volcanics and volcaniclastic sediments intercalated. The palynomorphs are of variable thermal maturity (within and between samples), probably reflecting differential heating associated with the complex volcanic/hydrothermal system. The new palynological data provide, for the first time, a reliable biostratigraphical age for the deposits, and suggest that they accumulated relatively rapidly. Spore biostratigraphy and thermal maturity studies facilitate correlation of the tectonically complex deposits, and shed light on other aspects of the geological history of the outlier. The palynomorph assemblages also aid interpretation of the biota of the Rhynie basin, including the exceptionally preserved biotas of the Rhynie and Windyfield cherts.

Lochkovian (earliest Devonian) miospores from the Solimões Basin, northwestern Brazil

Eighteen core samples from PETROBRAS well 1-JD-1-AM (Jandiatuba area, Solimões Basin, northwestern Brazil) have been studied for miospores. Fifty-three species are identified. This assemblage is tentatively correlated with the Z Phylozone of the BZ Oppel Zone ( Steemans, P., 1989. Palynostratigraphie de l'Eodévonien dans l'ouest de l'Europe. Professional Paper. Mémoires Explicatifs pour les Cartes Géologiques and Minéralogiques de la Belgique, 27, pp. 453.), dated late Lochkovian. This is in accordance with previous age determinations based on chitinozoans and acritarchs. Numerous representatives of the miospore genus Dictyotriletes are observed. These enable recognition of the Dictyotriletes emsiensis morphon, an informal classification unit which includes Dictyotriletes granulatus, D. emsiensis, Dictyotriletes cf. subgranifer, specimens previously misassigned to D. subgranifer and some Dictyotriletes spp. provisionally left in open nomenclature. Since all intermediate forms from typical D. granulatus to typical D. emsiensis coexist, it is currently difficult to determine the base of “E” Interval Biozone in South America as originally defined in Western Europe. It is suggested, therefore, that the base of the “Ems” Biozone defined in Brazil cannot be correlated with the base of the “E” Biozone. Instead, it should be included in an interval of uncertainty ranging from the European “Si” to “E” Biozones. Indeed, the underlying “NsZ” Biozone from South America contains species not known below the “Si” Biozone. Here, the D. emsiensis morphon Assemblage Zone is erected, which may be coeval with the “N” through “E” Biozones of Western Europe. The PISA palynoflora from the Paraná Basin is also attributed to this new biozone. However, in the absence of species observed in the “BZ” Biozone (and also in the Solimões Basin), the PISA assemblage could be somewhat older than that of well 1-JD-1-AM.

Counting taxonomic richness from discrete biochronozones of unknown duration: a simulation

Counts of taxonomic richness and derivates such as origination and extinction rates should ideally be scaled against absolute time. However, calibration of the fossil record with absolute time is often wanting or lacking at the zone level, which is the most resolved level that can be reached for long-distance correlations based on faunal content. For discrete biochronozones based on the maximal association principle (Oppel zones, concurrent-range zones, unitary-association zones), the relation between taxonomic richness and absolute duration of maximal associations is explored by means of an inverse Monte-Carlo approach. Simulations indicate that only a minor and negligible fraction (6% on average) of changes in taxonomic richness can be explained by changes in absolute duration of maximal associations. This very weak relation is shown to hold whatever the mean values of Poisson-type distributions of longevity of taxa, the various degrees of completeness of the record, and the intensity of a superimposed extinction phase. Hence, biochronozones based on the principle of maximal association provide a very robust and reliable basis for counts of taxonomic richness. However, as the mean of the distribution of longevities strongly controls the taxonomic richness and the number of constructed maximal associations, great caution is required when comparing fluctuations of taxonomic richness of different clades in time and space. On the other hand, and all other things being equal, the comparison of taxonomic richness of clades across stratigraphic successions is shown to be reliable irrespective of the biostratigraphic completeness of the sequences. Finally, during extinction phases, the number of zones is shown to increase, whereas the mean duration of zones is found to decrease strongly, leading to a significantly negative correlation between the percentage of disappearing taxa and the total amount of time represented by zones. This last result clearly emphasizes the methodological inappropriateness of the widely used equal zone-duration approach.