Bollettino SPI Vol. 37 - Issues 1, 2-3
Issue 1
Published in July 1998
- Parisi G., Baldanza A., Benedetti L., Mattioli E., Venturi F. & Cresta S. (1998)
Toarcian stratigraphy of the Colle d’Orlando section (Umbria, Central Italy, northern Apennine)
pp. 3-39
A detailed biostratigraphic study based on ammonites and calcareous nannofossils was carried out in the Colle d’Orlando section (Central ltaly). This succession is characterized by a regular alternance of marly and limestone levels, Toarcian in age. Fifty seven Ammonite assemblages belonging to seven biozones, seven subzones and one biohorizon were recognized. They comprise all the Toarcian Standard Ammonite Zones with the exception of the Bonarellii Zone. The ammonite assemblages exhibit a Mediterranean affinity. Several calcareous nannofossil events are recognized in the Late Domerian to Early Bajocian of the Colle d’Orlando section and some considerations regarding the assemblage composition and preservation state are presented here. The continuous and relatively abundant record of ammonites and calcareous nannofossils allows for an integrated biostratigraphy and a precise correlation of calcareous nannofossil events to ammonite biohorizons.
- Carboni M.G. & Palagi I. (1998)
The Neogene – Quaternary deposits of the coastal belt between the Tafone and Marta Rivers (Northern Latium)
pp. 41-60
Four boreholes, out of the several boreholes drilled in the Plio-Pleistocene deposits of the coastal belt of Northern Latium, were analyzed in detail for their micropaleontological content.
Foraminiferal distribution allowed us to reconstruct the biostratigraphy of the core-sampled interval and infer the paleoenvironmental condition of the area.
Benthic foraminiferal assemblages were correlated with sedimentary patterns, sea level and possible climate changes during the Plio-Pleistocene interval, and compared with other outcropping successions and boreholes drilled offihore. In the Early Pliocene-Early Pleistocene interval five planktonic foraminiferal biozones were recognized: the Globorotalia margaritae Zone, the Globororalia puncticulata Zone, the Globorotalia aemiliana Zone, the Globorotalia inflata Zone, and the Globigerina cariacoensis Chronozone.
The study reiterates the presence of previously reported Upper Pliocene deposits and discusses their relationships with the Pleistocene marine transgression. Taking into account the different regional interpretations of this sector of Central ltaly, a stratigraphic framework was reconstructed showing that during the considered interval sediment deposition of the Neoautochthonous Cycle occurred in belts parallel to the modern coastline.
- Barra D., Bonaduce G. & Sgarrella F. (1998)
Paleoenvironmental bottom water conditions in the early Zanclean of the Capo Rossello area (Agrigento, Sicily)
pp. 61-98
The Pliocene “Trubi” Formation outcropping in Southern Sicily, has been so far the object of numerous researches only on composite sections. To obtain a continuous succession of unweathered sediments considered more suitable for paleomagnetic studies and cyclostratigraphical analyses, a continuous core drilling has been performed in the area East of Capo Rossello, between Punta di Maiata and Punta Grande. The bore-hole crossed the basal part of the Monte Narbone Formation, all the “Trubi” Formation and about 1 m of the underlying Messinian “Arenazzolo” Formation with a recovery of 99%. The complete drilling reached 155.26 m below ground surface.
The present paper deals with the paleoecological bottom water changes during the Zanclean from M Pl 1 to the lower part of M Pl 3 Biozones by means of the detailed quantitative analysis of benthic foraminifers and ostracods. The assemblages are typical of lower epibathyal zone all along the succession with benthic foraminifers that document a depth-range from 600 to 800 m. The two faunal groups pointed out different colonization patterns. The benthic foraminifers show a quick re-colonization at the base of the succession, almost completed in the lower part of M Pl 2 Biozone, whereas the ostracods show a slow fluctuating re-colonization along M Pl 1 and M Pl 2 Biozones and a rapid increase only a few meters above the M Pl 2 – M Pl 3 boundary.
Moreover some principal bioevents have been identifìed. Above the initial re-colonization at the base of the M Pl 1 Biozone, the assemblages change rapidly in the upper part of the same biozone. This interval is characterized by the ‘Uvigerina pygmaea – peregrina Event’, among the benthic foraminifers, and by a remarkable reduction of the ostracods assemblages in both number of species and specimens, indicative of a clearly defined dysaerobic or kenoxic phase with bottom slowed circulation. These conditions quickly change at the base of the M Pl 2 Biozone with the beginning of improving bottom oxygenation characterized by the FOD of Agrenocythere pliocenica, typical psychrospheric ostracod, and of Cibicidoides robertsonianus, a benthic foraminifer characteristic of the NADW. A second change starts from the middle part of the M Pl 2 Biozone. In fact, the benthic foraminiferal co-dominant assemblages are characterized by species related to increased productivity and circulation. This change begins a few meters below the FO of Globorotalia puncticulata, a species which testifies a slight cooling. Therefore the benthic foraminifers seem to show a paleoenvironmental cooling-related bottom change, which occurs shortly before the FO of this planktic foraminifer. From the base of M Pl 2 upwards the ostracods testify the entrance of the psychrosphere which becomes stabilized within this biozone and a graduai improvement of bottom circulation. From M Pl 3 Biozone, after the paleoclimatic change, the assemblages are abundant and well diversified and indicate that the paleoceanographic conditions at the bottom improved and evolved to become more stable.
Finally a probable correlation of the quantitative distribution of Planulina ariminensis (benthic foraminifer) with a maximum in the eccentricity astronomical record of 400 ky has been pointed out.
- Barra D., Bonaduce G. & Ciarcia S. (1998)
Evidence of brackish lagoons in the Pliocene of Irpinia (Southern ltaly)
pp. 89-98
The sedimentary section outcropping in the locality S. Andrea near Montecalvo Irpino has indicated the presence of paleoenvironmental characters which are referred to as a marine basin margin evolving to the regressional phase. This succession is constituted by coastal sandy sediments which end at the top with silty-clays lagoonal sediments.
The analysis of the sedimentary facies and the studied ostracod fauna allowed the defìnition of 4 facies assemblages (A1-A4) each of which is characteristic of different environmental conditions: upper shoreface – foreshore, coastaf eolic dunes, washover fan and brackish lagoon.
As far as the ostracodes are concerned, two new species are established and illustrated, Euxinocythere (Maeotocythere) nasseri n. sp. and Leptocythere lagunaris n. sp. from brackish environments.
- Reisinger C. & Hohenegger J. (1998)
Sexual dimorphism in limb bones of Late Pleistocene cave bear (Ursus spelaeus, Carnivora, Mammalia) from three caves in Eastern Alps (Austria and ltaly)
pp. 99-116
The length and width of cave bear (Ursus spelaeus) stylo- and zeugopodia were measured. The material comes from three Late Pleistocene alpine caves: Conturines Cave in Northern Italy, Gamssulzen Cave in Upper Austria, and Herdengel Cave in Lower Austria. With the help of hierarchical cluster and discriminant analysis, all of the elements under study may be classified into two groups. Size differences between limb bones are interpreted in terms of sexual dimorphism. Such dimorphism of size may be observed in all recent bear species. This paper argues against a “High-Alpine small form” far the remains of the Conturines Cave as tested by one-way analyses of variance.
- Tsoukala E. & Lister A. (1998)
Remains of straight-tusked elephant, Elephas (Palaeoloxodon) antiquus Falc. & Caut. (1847) ESR-dated to oxygen isotope Stage 6 from Grevena (W. Macedonia, Greece)
pp. 117-139
A partial skeleton of straight-tusked elephant, Elephas (Palaeoloxodon) antiquus, was excavated from Pleistocene deposits at Grevena, western Macedonia, in 1992-95. The skeleton includes substantial portions of the skull and vertebral column, and represents a large, adult male of about 40 years. Additional remains include fragments of at least one other individual of E. (P.) antiquus and a large bovid cf. Bos primigenius. Three samples of elephant tooth enamel were ESR-dated (by Y. Bassiakos), giving an age in the range 160-170 kyr BP, i.e. Oxygen Isotope Stage 6. This indicates Greece as a refugium for temperate, woodland-adapted large mammal species at a time when they were largely excluded from northern and central Europe.
Issues 2-3
Published in November 1999
- Stouge S. & Bagnoli G. (1998)
The suprageneric classification of some Ordovician prioniodontid conodonts
pp. 145-158
Phylogenetic relationships among higher taxa within the conodonts that developed a complex apparatus and the resulting classifications are not universally agreed upon due to the different patterns of the apparatus evolution within the class. Using the most recent reconstructions of the prioniodontid apparatuses a picture of their evolution is obtained. The proposed classification is based on diffirent apparatus styles which persisted as unbroken lineages.
The proposed suprageneric classification for the prioniodontids includes the order Prioniodontida Dzik, 1976 with the superfamilies Prioniodontoidea Bassler, 1925 and Balognathoidea Hass, 1959. The new order Polyplacognathida with the family Polyplacognathidae Bergström, 1981 and the new family Cahabagnathidae is introduced.
- Löfgren A., Repetski J.E. & Ethington R.L. (1998)
Some trans-Iapetus conodont faunal connections in the Tremadocian
pp. 159-173
Paleobiogeographical barriers within the Iapetus Ocean effectively restricted conodont faunas in Baltica from contact with those in Laurentia during Tremadocian time. Only species of Cordylodus, Paltodus, Drepanodus, Paroistodus and Iapetognathus have been reported to occur on both sides of the Iapetus Ocean. Continued studies of faunas from deeper platform and slope settings of North America (Laurentia) and generally deeper water faunas of Scandinavia (Baltica) reveal that these faunas share a few more species. One of these taxa was first described as Oneotodus variabilis Lindström, 1955, from upper Tremadocian beds of south-central Sweden. It now has been recovered from Nevada and Pennsylvania as well. Its apparatus appears to be seximembrate, with only minor geographic variation of elements between Baltica and Laurentia. Comparison with species of the Laurentian genus Variabiloconus Landing, Barnes & Stevens, 1986, has convinced us that “O.” variabilis should be transferred to Variabiloconus. A closely related taxon, Variabiloconus transiapeticus n. sp., is reported from south-central Sweden, Nevada and Colorado, strengthening the connection between conodont faunas in the two paleocontinents in the Tremadocian. Moreover, a few specimens of the North American zonal index species Rossodus manitouensis Repetski & Ethington, 1983, have been found in samples from the Paltodus deltifer Zone in Scandinavia, confirming previous correlations and demonstrating that even the strictest paleobiogeographical delimitations can sometimes be overcome.
- Löfgren A. (1998)
A septimembrate apparatus model for the Ordovician conodont genus Cornuodus Fåhræus, 1966
pp. 175-186
An investigation of the Ordovician conodont genus Cornuodus, based on the literature and a collection of almost 8,000 elements from Swedish sections, has led to the conclusion that its apparatus is septimembrate with Pa, Pb, Sa, Sb, Sc, Sd1 and Sd2 elements. All previously described Cornuodus forms are referred to a single species, C. longibasis, but different ecomorphotypes can be distinguished. The species has an extensive stratigraphical range, from the Tremadoc into the Ashgill. Its environmental preferences are discussed and the element types are described in detail.
- Wang Z. & Bergström S.M. (1998)
Conodont-graptolite biostratigraphic relations across the base of the Darriwilian Stage (Middle Ordovician) in the Yangtze Platform and the JCY area in Zhejiang, China
pp. 187-198
Although the recently ratifìed stratotype of the base of the global Darriwilian Stage in China has a magnificent graptolite succession, conodonts in the boundary interval are not very diagnostic biostratigraphically and the precise graptolite/conodont zone relations have not been well established. In an effort to clarify these relations, conodont samples were collected from coeval strata in three Yangtze Platform sections with occurrences of graptolites of the lowermost Darriwilian U. austrodentatus graptolite Zone. Biostratigraphically highly diagnostic Baltic conodonts were found that make it possble to apply the Baltic conodont zone scheme to the study sections. Although the restricted and spotty occurrences of graptolites in these sections make it difficult to recognize the exact level of the base of the Darriwilian, the new data are consistent with the idea that this level may be near the base of the Baltoniodus norrlandicus – Microzarkodina parva Zone.
- Lehnert O., Bergström S.M., Keller M., Bordonaro O. (1998)
Ordovician (Darriwilian-Caradocian) conodonts from the San Rafael Region, west-central Argentina: biostratigraphic, paleoecologic, and paleogeographic implications
pp. 199-214
Conodonts from the Lindero Formation at its type locality south of San Rafael, Mendoza Province, represent the Eoplacognathus reclinatus–E. lindstroemi Subzones of the Pygodus serra Zone and the Amorphognarhus inaequalis Subzone of the Pygodus anserinus Zone. The species associations of these conodont faunas are comparable with those in deeper-water successions in the Precordillera to the north, and also with those in low latitude outer platform and slope deposits in Laurentia, and in higher-latitude carbonate platform strata in northwestern Europe. The San Raphael Block is part of the Cuyania Terrane, and the ‘cold water’ conodont fauna in shallow-water strata in the lower part of the the studied succession is of special paleogeographic significance in suggesting that this region, as well as the rest of the Cuyania Terrane, by Middle Ordovician time was considerably geographically separated from Laurentia and apparently occupied a higher-latitude position between Laurentia and western Gondwana.
- Ferretti A. & Serpagli E. (1998)
Late Ordovician conodont faunas from southern Sardinia, Italy: biostratigraphic and paleogeographic implications
pp. 215-236
Conodont faunas recovered from several localities in southwestern and southeastern Sardinia are assigned to the Late Ordovician on the basis of the recovery of Amorphognathus ordovicicus Branson & Mehl, 1933 and A. lindstroemi (Serpagli, 1967). A peculiar Amorphognathus species that has been found in slightly older sediments is described. 28 species belonging to 18 genera constitute the conodont collection; elements of Hamarodus europaeus (Serpagli, 1967) and Scabbardella altipes (Henningsmoen, 1948), together with those of Amorphognathus, numerically dominate the fauna. The same dominance was already reported in the “Tonflaserkalk” of the Carnic Alps (Serpagli, 1967). Taxa of the genera Plecrodina, Dichodella, Sagittodontina, Istorinus and Icriodina are described and discussed for the first time for Sardinia. The conodont fauna, composed of about 13000 elements obtained by the processing of about 550 kg of limestones, includes species typical of the Mediterranean Province. Nevertheless, the extreme paucity of its markers Sagittodontina robusta Knupfer, 1967 and Istorinus erectus Knupfer, 1967, which together represent less than one per cent of the fauna, and the presence of other typical indicators of lower latitude affinity like Plectodina and Dichodella reveal the mixed character of Sardinian fauna. Together with the Carnic Alps, Sardinia probably occupied an outer position of lower latitudes (compared to the typical north-Gondwanian regions of the circumpolar belt) where faunistic interchange with both the British and Baltic provinces was possible.
- Dzik J. (1998)
Evolution of the Late Ordovician high-latitude conodonts and dating of Gondwana glaciations
pp. 237-253
The presence of the rapidly evolving conodont lineage of Amorphognathus in the Middle and Late Ordovician of the Holy Cross Mountains (Po land) enables correlation of environmental events there with those from other areas of the world. The faunal succession of the conodonts records especially well the profound climatic changes in the Ashgill. The record can be calibrated climatically on the basis of periodic immigrations of species known to be abundant either in the Ordovician subpolar regions (Sagittodontina, Scabbardella) or subtropics (Rhodesognathus, Icriodella, Birksfeldia). Increased contribution of Scabbardella is generally connected with a decrease in taxonomic diversity of the species association. A general trend toward cooling, which is partially reversed close to the end of carbonate sedimentation in the area, is shown. The phyletic succession of Amorphognathus chronospecies is shown stratophenetically. This is used to propose a provisional correlation of the events recorded in the Holy Cross Mountains with those within the carbonate sedimentation intervals in areas closer to Gondwana. A late population of A. tvaerensis, which shows much similarity to the Thuringian Kalkbank A. ventilatus and presumably being ancestral to it, cooccurs in the Holy Cross Mountains with Rhodesognathus. This suggests that the Kalkbank warm event was coeval with the topmost phosphate rich part of the Mójcza Limestone immediately above, where A. superbus occurs. A. sp. n., which characterizes the lower part of the marly strata above the Mójcza Limestone with a lowest diversity assemblage, is known also from lateral equivalents of the Kullsberg mud mound limestones of Sweden. Its transition to A. ordovicicus corresponds to the peak of abundance of cold-water species. The proposed transition from A. ordovicicus to A. duftonus and a significant increase in contribution of Dapsilodus at the expense of Scabbardella preceded the cessation of carbonate sedimentation in the area and it seems to be coeval with similar events in the Carnic Alps.
- Corradini C. & Serpagli E. (1998)
A Silurian conodont biozonation from late Llandovery to end Přídolí in Sardinia (Italy)
pp. 255-273
The standard Late Llandovery – Top Přídolí conodont zonation between the top of the celloni Zone and the latest Přídolí detorta Zone is revised on the basis of data from the Silurian System of Sardinia. Fifteen biointervals have been recognized; among them, one zone is here newly named (Oz. exc. hamata) and three more zones (K. crassa, K. v. variabilis interval Zone and Pe. latialata), proposed and sporadically used in some previous biozonations, are reintroduced. The scheme provided for Sardinia fìts well in other part of the world, like the Cellon section.
- Serpagli E. & Corradini C. (1998)
Taxonomy and evolution of Kockelella (Conodonta) from the Silurian of Sardinia (Italy)
pp. 275-298
Relatively abundant specimens of Kockelella found in Sardinia permit a revision of many taxa of this important genus and an attempt at a more complete reconstruction of the phylogeny of the whole group.
Besides the two new taxa recently (1998) proposed by us (K. maenniki and K. v. ichnusae), which are here re-described and re-discussed, a new subspecies, K. absidata sardoa of the K. absidata group, is proposed. Furthermore the reconstruction of the apparatus of K. crassa is presented. The biostratigraphic value of the taxa of the genus Kockelella is also stressed.
- Viira V. (1998)
Late Silurian conodont biostratigraphy in the northern East Baltic
pp. 299-310
Conodont biostratigraphy of the late Silurian Paadla to Ohesaare stages of the northern East Baltic is described based on the conodont fauna collected over a long period from the rock samples of many outcrops and about 20 borehole sections. The conodont distribution from shallow shelf (Kolka borehole) through open shelf (Ohesaare and Ventspils boreholes) to deeper part (Pavilosta borehole) of the Palaeobaltic Basin is discussed. A stratigraphically rather sharp faunal change took place on the boundary of the Paadla and Kuressaare stages. The studied interval includes the snajdri, crispa and remscheidensis zones. The fast zone is subdivided into four subzones: baccata, eosteinhornensis, canadensis and remscheidensis. The eosteinhornensis Subzone marks the beginning of the Přídolí. The detorta Zone occupies a short interval in the remscheidensis Subzone.
- Benfrika E.M. (1998)
Some upper Silurian – middle Devonian conodonts from the northern part of Western Meseta of Morocco: systematic and palaeogeographical relationships
pp. 311-319
This is the first report on Wenlock-Givetian conodonts from the northern part of Western Meseta of Morocco. The systematic study of this North African material brings complementary data on the palaeogeographic distribution over the world at this period. Faunal affinities are recognised between Western Moroccan Meseta, Central Europe and North America, particulary during the Upper Silurian and Lower Devoman.
- Murphy M.A. & Valenzuela-Ríos J.I. (1998)
Lanea new genus, lineage of Early Devonian conodonts
pp. 321-334
Lanea n. gen. is based on a sequence of Pa elements that occurs in the middle Lochkovian central Nevada and in the Spanish Pyrenees. In addition, parts of the sequence are known in Alaska, Czech Republic, Austria and Sardinia. The taxa in the lineage enable a subdivision of middle Lochkovian strata that reinforces and refines that suggested by members of the genera Ancyrodelloides, Pedavis and Flajsella. The Lanea clade begins at the base of the middle Lochkovian with the transformation of eosteinhornensis group taxa to L. omoalpha n. sp. (= “Ancyrodelloides omus α” of Murphy & Matti, 1983). This taxon is interpreted as the progenitor of L. eoeleanorae n. sp. L. eoeleanorae gives rise to L. eleanorae (Lane & Ormiston, 1979 ), which in turn gives rise to L. telleri (Schulze, 1968) ( = “Ancyrodelloides eleanorae” of Klapper & Murphy, 1980), the latest member of the series. The clade disappears in the above-mentioned regions in the upper part of the trigonicus–pandora β Zone towards the end of the middle Lochkovian.
The transitions within the Pa elements of the lineage show many intermediate morphologies that overlap stratigraphically suggesting an incremental mode for the evolutionary changes. During the process the basal cavity, which is open at the onset becomes progressively more restricted. The basal platform lobes become terraced and the terraces get progressively larger until they occupy the entire upper surface of the basal platjorm. In the later forms, the basal cavity is constricted, the anterior and posterior blades develop benches that extend from the platform terrace, and the platform terrace develops a rim in the latest described form.
- Yolkin E.A. & Izokh N. (1998)
Rates of evolution in the Emsian (Early Devonian) conodont and trilobite lineages
pp. 335-338
Evolutionary rates within Emsian trilobite and conodont lineages are considered against the background of precise alignments of regional stratigraphic units and sea-level fluctuations, according to the standard conodont zonation. Three steps of morphological change of equal magnitude within the Ganinella lineage coincide with three successive eustatic T-R cycles. These steps are aligned with three stages in change of basal cavity and adcarinal troughs of polygnathids. At the base of the kitabicus and nothoperbonus zones (Zinzil’ban and Daleje event levels) the evolutionary rate of this fossil group accelerates, resulting in short-range species lineages. Two-fold and three-fold divisions of the Emsian Stage into substages are discussed.
- Klapper G. & Becker R.T. (1998)
Comparison of Frasnian (Upper Devonian) Conodont Zonations
pp. 339-348
Previously it has not been possible to correlate the thirteen-fold Frasnian conodont zonation first developed in the Montagne Noire, southern France, with the nine-fold standard zonation of the Frasnian. The impasse has been due to the fact that the taxonomies underlying the two zonations are so disparate that comparisons of faunal lists and range charts lead to substantial misalignments. We propose here an alignment of the two zonations, based on our sampling of the Martenberg reference section of the standard zonation in the Rhenish Slate Mountains of Germany, combined with application of the taxonomic concepts underlying the Montagne Noire zonation to the conodonts recovered.
- Ovnatanova N.S., Kuzmin A.V. & Menner V.V. (1998)
The Succession of Frasnian Conodont Assemblages in the Type Sections of the Southern Timan-Pechora Province (Russia)
pp. 349-360
A succession of 11 conodont assemblages, covering the entire interval of the Frasnian Stage, Upper Devonian, is established according to reference section of Southern Timan (northeastern East European Platform). The conodont assemblages are correlated with the regional stages. The Lower Frasnian assemblages characterize shallow-water lithofacies and are based on the evolution of Ancyrodella and Polygnathus. The Middle and Upper Frasnian assembiages are established in the sections of slope and basinal lithofacies, with palmatolepids prevailing. The levels of the greatest changes of conodont assembiages are determined. Problems, arising in correlating the Timan-Pechora succession with the Standard Frasnian conodont Zonation, as well as with the Montagne Noire zonation, are discussed.
- Savage N.M. & Yudina A.B. (1998)
Late Devonian Syv’yu River Section, Timan-Pechora Basin, Northwestern Russia
pp. 361-373
This paper deals with the Upper Devonian conodont biostratigraphy in the Syv’yu River section (western Subpolar Urals), one of the most complete Frasnian-Famennian sequences within the Timan-Pechora Basin (Russia). Lithostratigraphically, the Upper Devonian sequence in the section is subdivided, in ascending order, into the Kedzydshor, Vorota, Shar’yu and Domanicoid Formations. The following zones of the Late Devonian standard conodont zonation have been recognized: in the Frasnian, Early and Late falsiovalis, transitans, punctata, Early and Late hassi, jamieae, Early and Late rhenana, and linguiformis Zones; in the Famennian – Early, Middle and Late triangularis, Late crepida, and Early marginifera Zones. The Middle falsiovalis Zone is not recognizable because of an hiatus probably spanning an interval from the late Early(?) falsiovalis to the earliest part of the Late falsiovalis Zone. Ancyrodella and Ancyrognathus are rare. Icriodus is generally rare but common in argillaceous limestones at the Frasnian-Famennian boundary.
- Schülke I. (1998)
Early Famennian conodont biostratigraphy of the stratotype area (Montagne Noire, Southern France)
pp. 375-391
The early Famennian deposits of three important sections (Abandoned quarry Coumiac, Causses et Vryran, and La Serre trench C) from the Montagne Noire are stratigraphically analysed. In contrast to former studies, the regional conodont succession reveals extensive differences compared to the global one. Several index fossils used for the identification of Late Devonian conodont zones are lacking or appear delayed in the faunal record. Consequently, a regional conodont stratigraphic scheme extending from the Frasnian/Famennian boundary to strata as young as Middle crepida-age is proposed and correlated with the Late Devonian standard conodont zonation. Furthermore, conodont faunal composition is estimated to be triggered by sea-level changes of the 3rd and 4th order. Implications especially for the duration of conodont zones in the early Famennian are discussed.
- Sanz-López J., García-López S., Montesinos J.R. & Arbizu M. (1998)
Biostratigraphy and sedimentation of the Vidrieros Formation (middle Famennian-lower Tournaisian) in the Gildar-Montó unit (northwest Spain)
pp. 393-406
Famennian to lowermost Tournaisian associations of conodonts, ammonoids and trilobites have been recorded from a section of the Vidrieros Formation in the Cantabrian Zone. The faunal associations range from the Lower marginifera to the sulcata conodont Zones. The location of Devonian/Carboniferous boundary in the formation has been discussed and lithological, and faunal changes have been found at the positions of the Enkeberg, annulata and Hangenberg Events. The relationships between Famennian conodont associations along the Cantabrian Zone and the changes in the rate of basin subsidence are outlined.
- Mawson R. & Talent J.A. (1998)
Early Carboniferous (mid-Tournaisian) conodonts from north-eastern Queensland (Ruxton and Teddy Mountain Formations): age-implications and stratigraphic alignments
pp. 407-425
A gap in our knowledge of conodont zonation is closed by faunas from a limestone turbidite series in Rheinisches Schiefergebirge, Germany. Gnathodus bilineatus (Roundy, 1926) sensu lato originates with two morphotypes high in the Pericyclus-Stufe, cu II, Lower Carboniferous. Gn. bilineatus romulus n.ssp. enters still in the uppermost Entogonites nasutus Zone. Gn. bilineatus remus n.ssp. follows suite in the E. grimmeri Zone. Gn. bilineatus bilineatus appears in the Goniatites crenistria Zone. Gn. girtyi Hass, 1952 precedes Gn. bilineatus romulus n.ssp. by just a few beds and therefore starts within the Entogonites nasutus Zone. The ancestry of Gn. praebilineatus Belka, 1985, most likely the ancestor of Gn. bilineatus, remains uncertain. It is recommended to set the base of the Gnathodus bilineatus Zone with the first appearance of Gnathodus bilineatus romulus n.ssp.
- Meischner D. & Nemyrovska T. (1998)
Origin of Gnathodus bilineatus (Roundy, 1926) related to goniatite zonation in Rheinisches Schiefergebirge, Germany
pp. 427-442
The early Famennian deposits of three important sections (Abandoned quarry Coumiac, Causses et Vryran, and La Serre trench C) from the Montagne Noire are stratigraphically analysed. In contrast to former studies, the regional conodont succession reveals extensive differences compared to the global one. Several index fossils used for the identification of Late Devonian conodont zones are lacking or appear delayed in the faunal record. Consequently, a regional conodont stratigraphic scheme extending from the Frasnian/Famennian boundary to strata as young as Middle crepida-age is proposed and correlated with the Late Devonian standard conodont zonation. Furthermore, conodont faunal composition is estimated to be triggered by sea-level changes of the 3rd and 4th order. Implications especially for the duration of conodont zones in the early Famennian are discussed.
- Somerville H.E.A. & Somerville I.D. (1998)
Late Viséan conodont biostratigraphy and biofacies in the Kingscourt area, Ireland
pp. 443-464
The Gnathodus bilineatus and Lochriea nodosa zones are recognised in the Kingscourt area, Ireland in both platform and basinal facies. The base of the nodosa Zone is defined by the synchronous first occurrence of L. nodosa and L. mononodosa in the same bed. Several conodont species (e.g. Mestognathus bipluti, Idioprioniodus healdi and Kladognathus macrodentata) are mostly restricted to the Brigantian (upper part of the bilineatus and nodosa zones). The richest and most diverse conodont faunas dominated by species of Gnathodus and Lochriea are from late Brigantian platform and basinal limestones within the L. nodosa Zone (Gnathodus–Lochriea Biofacies). Lower yields and diversity are recorded from early Brigantian platform limestones (upper part of the G. bilineatus Zone); with the poorest conodont yields in late Asbian platform limestones and mudmounds of the lower G. bilineatus Zone. There is a significant rise in the abundance and diversity of conodonts above the Asbian/Brigantian boundary, a change which coincides with changes in foraminiferal assemblages and lithofacies; this indicates probable transgressive environmental influences. A second major increase in conodont abundance and diversity is recognised at the base of the nodosa Zone, in platform and basinal facies. Shallow-water, coarse-grained Asbian platform limestones are dominated by Synclydognathus geminus and Kladognathus tenuis complectens (Synclydognathus–Kladognathus Biofacies), the elements of which are often abraded and fragmented. The best preserved faunas are mostly from the wackestones in the nodosa Zone at Poulmore, which have the best representation of all apparatus components. The late Viséan conodont faunas from Kingscourt are comparable in diversity, abundance and taxa present to those in northern England, North Wales and Poland where cyclothemic sequence limestones occur. The upper beds of Poulmore probably correlate with uppermost Viséan limestones in northern England and Lublin Basin, SE Poland.
- Merrill G.K. (1998)
Neognathodus and the species concept in conodont paleontology
pp. 465-473
Evolution has two products; speciation and phylomorphogeny. True biologic species are genetically defined whereas morphotypes are produced by phylomorphogenetic change and have the primary utility in biostratigraphy. Confusion between morphotypes and species is commonplace, does nothing to enhance biostratigraphy, indeed may impede it, at the same time confusing the taxonomy and imparting an undeserved taxonomic legitimacy to the morphotypes. Resolution of the paleontologic problem of recognizing species when only morphologies are available is diffìcult, but can be more closely approximated than is common practice.
Neognathodus, with its rapidly evolving suite of morphotypes is an ideal taxon to which to apply this concept for revised speciation based upon distributions of morphotypes. Although increased numbers enhance statistical probabilities, redefining species in this manner based on large collections permits reasonably confident identifications of species and determinations of geologic age in small to very small collections.
- Orchard M.J. & Rieber H. (1998)
Multielement Neogondolella (Conodonta, upper Permian-middle Triassic)
pp. 475-488
Neogondolella is reconstructed as a multielement conodont genus bearing eight kinds of elements, seven of which are paired, making a total of fifteen elements in all. The Pa element is segminiplanate, the Pb angulate, Sa is alate, Sb1 is breviform digyrate, Sb2 is dolobrate, Sc1 resembles tertiopedate, Sc2 is bipennate, and M is breviform digyrate. The Sa and Sc elements commonly occur as separate anterior and posterior parts. This reconstruction is based on abundant collections of disjunct elements and is supported by natural assemblages of Neogondolella from Switzerland. The apparatus remained essentially the same from the Upper Permian through the Middle Triassic, with relatively minor changes in the morphology of some elements regarded as of specific rank. The apparatus of Neogondolella differs from that of other Triassic taxa which are nevertheless united in bearing enantiognathiform Sb 1 elements, on which basis they are classed as members of the superfamily Gondolellacea. Apart from the Sb elements, the morphology and apparatus plan of gondolellaceans generally correspond to that of the Ozarkodinida. Within the family Gondolellidae, Gondolella and Neogondolella can be distinguished on multielement grounds.
- Wang C. (1998)
Conodont Mass Extinction and Recovery from Permian-Triassic Boundary Beds in the Meishan Sections, Zhejiang, China
pp. 489-495
A high-resolution biostratigraphy and fine taxonomy are the basis for the study of mass extinction and recovery. The Meishan sections provide a good example. Conodonts are commonly considered to be a leading fossil group for the Permian and Triassic biostratigraphy. Conodonts of the Meishan sections have been studied extensively and ranges of all conodont species are clear. Clarkina subcarinata (Sweet) disappears at the top of the Changhsing Limestone; Clarkina deflecta (Wang & Wang) and C. xiangxiensis (Tian) disappear within boundary bed 2 (or bed 26); the range of Clarkina meishanensis Kozur & Wang is confined to boundary bed 1 (or bed 25,26); Clarkina carinata (Clark) appears somewhat earlier than Hindeodus parvus (Kozur & Pjatakova); Clarkina changxingensis (Wang & Wang) extends up across the boundary and disappears in the upper part of boundary bed 2; Hindeodus parvus, which evolved from Hindeodus latidentatus praeparvus Kozur, appears first in the middle of boundary bed 2; Isarcicella staeschei Dai & Zhang appears in bed 28, 8 cm higher than Hindeodus parvus. The Meishan sections contain both the pelagic facies conodont Clarkina and the neritic facies conodont Hindeodus.
After a detailed study of conodonts from the Meishan sections, the present author recognizes that conodont mass extiction demonstrates a stepwise character, it was not a “sharp knife cut’. Compared with other fossil groups such as fusulinids and ammonoids, conodonts were the latest to become extinct in the P/T mass extinction. Duration of the conodont mass extinction is the shortest; and they were the earliest to recover as indicated by the FAD of Hindeodus parvus or the first appearence of Isarcicella staeschei. There were no conodont refugia or Lazarus taxa during the P/T mass extinction and recovery intervals. Clarkina carinata and Hindeodus latidentatus (Kozur, Mostler & Rahimi-Yazd) were crisis projenitor species; Hindeodus changxingensis C.Y. Wang and Clarkina meishanensis Kozur & Wang were disaster species or failed crisis progenitor taxa.
- Mastandrea A., Neri C., Ietto F. & Russo F. (1998)
Misikella ultima Kozur & Mock, 1991: first evidence of Late Rhaetian conodonts in Calabria (Southern Italy)
pp. 497-506
The succession cropping out in the Fosso Pantanelle area (Mt. S. Giovanni, Calabrian “Catena Costiera”; Upper Trias) provided a rich and well preserved conodont fauna. The basin stratigraphic succession is characterized by cherty lime mudstone with minor fine-grained calciturbidites and suspected tufites. Conodont fauna is dominated by M. hernsteini and M. posthernsteini in the lower and middle part of the section, and by M. ultima in the uppermost part. Every species is represented by a great number of specimens. On the basis of the chronostratigraphic classification of Kozur & Mock (1991), the whole section may be referred to Rhaetian. Due to the good preservation and the great abundance of conodonts (some occurring in clusters), the calabrian Catena Costiera succession may represent a reference succession for the study of the latest Triassic conodont faunas and chronostratigraphy.
- Trotter J.A., Korsch M.J., Nicoll R.S. & Whitford D.J. (1998)
Sr isotopic variation in single conodont elements: implications for defìning the Sr seawater curve
pp. 507-514
Sr isotopic compositions of single conodont elements were measured to investigate the potential usefulness of conodonts in defining the Sr isotope seawater curve. Analysed elements had very low colour alteration indices (CAI = 1) and were of the coniform species Drepanodus arcuatus (Pander, 1856), sampled from the Early Ordovician (early Bendigonian, -490 -492Ma) Emanuel Formation in the Canning Basin of Western Australia.
87Sr/86Sr ratios measured from singe whole conodont elements were compared to those from mechanically separated cusp tissue and from the element base with attachment cone, showing significant isotopic heterogeneity within single elements. Cusps are characterised by significantly lower 87Sr/86Sr ratios (0.708949 – 0.709056) than their associated base and attachment cone (0.709503 – 0.709829), and are well within the boundaries of the seawater curve. Single whole elements have 87Sr/86Sr ratios (O. 709097 – O. 709282) intermediate between cusp and basal tissue. Host-rock limestone from the same horizon yielded high 87Sr/86Sr ratios (0.709368, 0.709454). A few small, thin-shelled articulate brachiopods recovered from elsewhere in the section have also sufffered significant diagenetic alteration; the 87Sr/86Sr measurements of secondary shell material range from 0.709027 to 0.709430.
These results indicate both carbonate and phosphate components have experienced significant diagenetic alteration, and that basal tissue appears to be a major source of secondary Sr in D. arcuatus. Despite the isotopic heterogeneity of conodont apatite, preliminary results suggest that the lowest, and perhaps primary, 87Sr/86Sr ratio (0.708750) is retained near the ‘core’ of cusp tissue, at the growth axis.
- Haunold Y., Dobrozemsky G., Krystyn L., Kiesl W. & Bichler M. (1998)
REE distributions in Triassic conodonts
pp. 515-525
Rare earth element (REE) concentrations of Triassic conodonts from the Tethys ocean were studied. Sampled sites in Austria (intraplatform basin with partial oceanic connection), Slovenia (restricted intraplatform basin), and Turkey (open-ocean regime) represent different depositional areas and environmental conditions. Samples were analyzed using Instrumentational Neutron Activation Analysis (INAA). The evaluation focused on the absolute concentrations of all REE (ƩREE), with special attention to Lanthanum (La) and Cerium (Ce) as well as to the Cen/Lan ratio. The geochemical values are compared with the geological framework of the studied sections. Oceanic water mass influence could be observed during the Carnian in section Bolücektasi Tepe (BT) and during the Upper Anisian in section Gamsstein (GS) and is documented geochemically by high concentrations of the element La. The Cen/Lan ratio documents in section Vrata Valley (VV) along a platform-basin originally oxidizing to reducing bottom water conditions. The section BT and GS further document the inverted relation of ƩREE versus sedimenation rate. A specific case is represented in section GS where unusal high amount of REE concentration results from volcanic ash input.
- Basden A. (1998)
Early Devonian microvertebrates from the Tyers-Boola area of central Victoria, Australia
pp. 527-541
The vertebrate microfauna from the Coopers Creek Formation, central Victoria, comprises platelets and dermal bone fragments from brachythoracid and acanthothoracid placoderms, rare chondrichthyan remains, scales of the acanthodians Trundlelepis cervicostulata, Nostolepoides platymarginata, Gomphonchus? bogongensis, Nostolepis sp., Acanthoides sp., Cheiracanthoides sp. and Poracanthodes sp., acanthodian fin spines, and rare osteichthyan teeth. Accompanying conodonts date the fauna as sulcatus–kindlei zones (Pragian, Early Devonian). Comparisons with coeval faunas from southeast Australia reveal many common taxa.
- García-Alcalde J.L. (1998)
Palaeogeography of Spanish lower Devonian Rhynchonellids
pp. 543-545
Old World Realm rhynchonellid genera occur also in the Eastern America Realm. The most direct migratory way was across the Gaspé Peninsula via Meguma (New Scotland). Plethorhyncha originated in the lberian Peninsula in the latest Silurian, colonized the Appalachian basin during the Pragian and earliest Emsian and fìnally reached Algeria through the Merrimack seaway at the beginning of the Emsian. Tectogonotoechia branched profusely in northern Gondwana and Baltica from Late Silurian onwards. Tectogonotoechia exploited the same Meguma-Gaspé way to reach the Appalachian basin during the Late Silurian. However, the genus used also a longer peri-Baltica route to colonize the Canadian Arctic Islands, Yukon, and Nevada, during the Early Devonian. Trigonirhynchia went on both migratory routes described above during the Emsian spreading largely on Meguma, Canadian Arctic Islands, Yukon, and Nevada, but rather surprisingly never reached the Appalachian basin.
- Schraut G. (1998)
The Carboniferous of Nötsch / Carinthia (Austria): compilation of fossil data and history of scientific publications
pp. 547-557
A compilation of fossil data from the Carboniferous of Nötsch, Carinthia (Austria), amassed during the past 190 years is presented. Several new fossil groups found during the last decade of research are listed. A complete list of taxa of rank is given together with comments on their diversity, abundance and date first mentioned in the literature. A historical view of scientiftc work since 1807 is tabulated including remarks on interpretation of age.