The Ordovician conodont Trapezognathus Lindström, 1955 in the Andean Basin, Argentina
6
Citation
13
Reference
10
Related Paper
Citation Trend
Abstract:
The central Andean basin is characterized by the presence of Ordovician deposits, distributed mainly in Northwestern Argentina.Conodonts from the Lower and Middle Ordovician were recovered from several outcrops from the Trapezognathus diprion Zone, Baltoniodus cf.B. triangularis, Baltoniodus triangularis Zone, and among them the genus Trapezognathus is highlighted.This paper describes and illustrates two species of this genus: T. diprion (Lindström) and T. quadrangulum Lindström.In addition we report that the conodont association suggests faunal affinity with Baltica and South China.Keywords:
Conodont
Tarim basin
Upper Cambrian (Furongian) and lowermost Ordovician conodonts are reported for the first time from the Kulumbe River section, northwest Siberian Platform. This section consists of a remarkably monotonous section of Cambrian and Ordovician shallow-water marine carbonates assigned to the Uyigur and Il'tyk Formations of the Mansian, Loparian and Nyaian regional stages. The 70 samples collected along the section produced 2870 identifiable conodont elements assigned to 23 species. The new data demonstrate that the upper Cambrian and lower Ordovician conodont faunas of the Siberian Platform are very similar to those reported elsewhere. The faunas are endemic at species level, but include genera that are widely distributed on other continents. Five new species are described including Hirsutodontus galerus sp. nov., Hirsutodontus limus sp. nov., Hispidodontus kulumbense sp. nov., Semiacontiodus asianus sp. nov. and Teridontus? angustus sp. nov. Based upon conodont evidence the Cambrian-Ordovician boundary is located within an unexposed 5 m thick interval in the upper part the Nyaian regional stage.
Conodont
Section (typography)
Acritarch
Cite
Citations (17)
Conodont
Sequence (biology)
Cite
Citations (174)
Lower Ordovician conodonts from the St. George Group of Port au Port Peninsula, Western Newfoundland
The St. George Group on the Port au Port Peninsula of western Newfoundland is little deformed, well exposed and provides a nearly complete sequence through the Lower Ordovician. The about 600 m thick succession records two depositional megacycles, and is divided into four formations in ascending order, the Watts Bight, Boat Harbour, Catoche and Aguathuna formations. -- Over 45,000 conodonts have been recovered from 432 3.5 kg samples from 10 sections comprising two composite sections through the St. George Group. The conodonts show excellent preservation with a low conodont Colour Alteration Index (CAI) of 1. Detailed taxonomic study of these faunas has permitted major revision to the reconstruction of Lower Ordovician multielement apparatuses, new interpretation of the phylogenetic relationships of Lower Ordovician, Midcontinent Province conodonts, and the establishment of a new and more refined Lower Ordovician conodont zonation for the Midcontinent Province. -- One of the major objectives of this study is to examine the Lower Ordovician conodont taxonomy. Seventy-five multielement species, representing 28 genera, have been described and illustrated, among them 7 new genera, 33 new species and 70 newly reconstructed multielement species. The new genera are Glyptodontus, Loxodentatus, Loxoqnathus,
Polycostatus, Striatodontus, Stultodontus and Tricostatus. The new species are: Acodus primus, Clavohamulus lonqicuspis, C. neoelonqatus, C. reniformis, C. sphearicus, Cristodus ethinatoni, Drepanodus nowlani, Glyptoconus felicitii, G. multiplicatus, G. priscus, Glyptodontus constrictus, G. expansus, G. tumidus, Loxodentatus bipinnatus, Loxognathus phyllodus, Loxodus latibasis, Macerodus crassatus, M. gracilis, M. wattsbightensis, Polycostatus falsioneotensis, P. minutus, Protopanderodus prolatus, Scolopodus subrex, Stritodontus lanceolatus, S. prolificus, S retractus, S. teridontus, Stultodontus ovatus, S. pygmaeus, Teridontus obesus, Tricostatus glyptus, Utahconus longipinnatus and Variabiloconus neobassleri. -- Three apparatus types, apparatus Type I, II and III, are redefined. Type I apparatuses consist of only a and e elements, and are characterized by stubby coniforms and extremely flattened forms. Type II apparatuses have three element morphotypes including a, c and e elements. Type III apparatuses contain four or five skeletal morphotypes: a, b, c, e and, commonly f elements. -- Following the taxonomic study, the local, regional and global stratigraphic range of the taxa were examined to help interpret evolutionary lineages. Nearly twenty such lineages have been recognized. Most are closely related to the Teridontus lineage, and belong to the Teridontus evolutionary complex. The evolutionary relationships of multielement taxa in the Teridontus complex show that the Teridontus lineage spread widely, evolving into both the Clavohamulus and Semiacontiodus lineages during the latest Cambrian. The latter probably produced the Variabiloconus and Polycostatus lineages during the earliest Tremadoc. Two important lineages, Glyptoconus and Striatodontus, appear suddenly, spreading widely, and diversifing rapidly during the early and middle Arenig. The late Tremadoc extinction is one of the most profound crises in conodont evolutionary history. This extinction leads to the demise of more than seven lineages including over 35 species. -- The conodonts recovered indicate that the St. George Group ranges in age from earliest Canadian to the earliest Whiterockian. Eight conodont Assemblage Zones have been established for the shallow-water (SW) facies of the typical Midcontinent Province. Six deeper-water (DW) conodont Assemblage or Lineage Zones have been recognized or redefined, and include some taxa with affinities to the North Atlantic Province. All the SW Assemblage Zones represent limited stratigraphic intervals in the Lower Ordovician, most can be recognized with other low latitude cratons, such as Australia, Siberia, and North China. In contrast, the DW Assemblage or Lineage Zones can be correlated through the critical biostratigraphic tie-points with the North Atlantic Province zonation.
Conodont
Peninsula
Cite
Citations (69)
Zhen, Y.Y. & Percival, I.G. March 2017. Late Ordovician conodont biozonation of Australia—current status and regional biostratigraphic correlations. Alcheringa 41, xxx–xxx. ISSN 0311-5518.Seven conodont biozones are recognized in the Upper Ordovician of Australia. The Pygodus anserinus, Belodina compressa and Phragmodus undatus–Tasmanognathus careyi biozones are successively represented in the Sandbian. Although the Erismodus quadridactylus Biozone of the late Sandbian North America Midcontinent succession was previously recognized in the Stokes Siltstone of the Amadeus Basin and the Mithaka Formation of the Georgina Basin in central-north Australia, we argue for a middle–late Darriwilian age for these two units. Four conodont biozones, from oldest to youngest the Taoqupognathus philipi, T. blandus, T. tumidus–Protopanderodus insculptus and Aphelognathus grandis biozones, are established in the Katian of eastern Australia. Taoqupognathus species are particularly useful in correlation of the lower–middle Katian successions of eastern Australia with contemporary rocks in other parts of eastern Gondwana and peri-Gondwana, such as with the three major terranes of North and South China and Tarim. These regions, together with Sibumasu and eastern Australia, were part of the Australasian Superprovince during the Late Ordovician, with a strong palaeobiogeographic identity signalled by domination of Taoqupognathus, Tasmanognathus and Yaoxianognathus. Longstanding difficulties for precise correlation with the well-established North American Midcontinent or Baltoscandian successions in the Late Ordovician, owing mainly to strong endemism of the Australian faunas particularly from shallow-water settings, have been resolved by integration of regional conodont biostratigraphic schemes. The conodont biozonation of the Australian Upper Ordovician reviewed herein also provides a crucial chronological reference for better constraining the temporal and spatial range of Late Ordovician tectonostratigraphic events across the intracratonic basins of northern and western Australia and orogenic belts of eastern Australia.Yong Yi Zhen* [yong-yi.zhen@industry.nsw.gov.au] and Ian G. Percival [ian.percival@industry.nsw.gov.au], Geological Survey of New South Wales, W.B. Clarke Geoscience Centre, 947–953 Londonderry Road, Londonderry NSW 2753, Australia.
Conodont
Biozone
Cite
Citations (27)
Abstract The Ordovician conodont faunal provinces were previously divided into the Midcontinent and Atlantic Faunal Regions situated respectively in low and high latitudes, where warm‐ and cold‐water type conodont faunas flourished respectively. According to the international correlation this paper proposes the third Ordovician conodont faunal region—Qinling Faunal Region, in which cold‐water conodont faunas were well developed in the Early to middle Middle Ordovician and warm‐water conodont faunas were well developed in the late Middle and Late Ordovician, indicating that the Qinling Region was situated in high latitudes earlier and in low latitudes later. The origin was only due to plate movement. In the Qinling Region the time interval of the change of the conodont fauna from the cold‐ to warm‐water type was 4 Ma (from 474 to 470 Ma), during which the fauna geographically spanned 40° of latitudes, with a movement velocity of nearly 1.12 m/a, indicating that the high‐latitude plates were divorced and reduced in the late Middle Ordovician, while the low‐latitude plates were converged and accreted. According to the features of the conodont faunas, the Qinling Faunal Region can be divided into the North Tarim, Wudang, Scandic and Pingliang provinces.
Conodont
Low latitude
Cite
Citations (3)
A new study on conodont biostratigraphy of Cambrian-Ordovician boundary in Yaowangshan Section, Qingzhou area, Shandong Province is first reported in this paper. 9 conodont zones have been recognized in the Chaomidian limestone formation, among which 3 are from the Lower Ordovician and 6 from the Fengshanian Stage of upper Upper Cambrian. The first discovery of the Cambrian-Ordovician Boundary species Iapetognathus fluctivagus in this section is of great significance. It will provide a new rule for Cambrian-Ordovician Boundary study in the Shandong area as well as in the whole North China. Additionally, through the further detailed study, the well-developed Yaowangshan Section will probably become the stratotype section in China, which will deeply affect the establishment of Cambrian stages, a still uncompleted work so far.
Conodont
Stratotype
Section (typography)
Cite
Citations (6)
This first study on chitinozoans from Greenland has revealed representatives of twenty-two chitinozoan species recovered from Ordovician and Silurian beds in North Greenland. The Ordovician faunas are sirnilar to those described from North Arnerica, while the Silurian faunas are more sirnilar to those of Baltoscandia. Four distinct assemblages can be separated between Maysvillian - early Garnachian and Ludlow. The chitinozoan biostratigraphy is in agreement with that of the graptolites but differs from the conodont biostratigraphy.
Conodont
Cite
Citations (15)
The long time interval after Pander's (1856) original conodont study can in terms of Ordovician conodont biostratigraphical research be subdivided into three periods, namely the Pioneer Period (1856–1955), the Transition Period (1955–1971) and the Modern Period (1971-Recent). During the pre-1920s, the few published conodont investigations were restricted to Europe and North America and were not concerned about the potential use of conodonts as guide fossils. Although primarily of taxonomic nature, the pioneer studies by Branson & Mehl, Stauffer and Furnish during the 1930s represent the beginning of the use of conodonts in Ordovician biostratigraphy. However, no formal zones were introduced until Lindström (1955) proposed four conodont zones in the Lower Ordovician of Sweden, which marks the end of the Pioneer Period. Because Lindström's zone classification was not followed by similar work outside Baltoscandia, the time interval up to the late 1960s can be regarded as a Transition Period. A milestone symposium volume, entitled 'Symposium on Conodont Biostratigraphy' and published in 1971, summarized much new information on Ordovician conodont biostratigraphy and is taken as the beginning of the Modern Period of Ordovician conodont biostratigraphy. In this volume, the Baltoscandic Ordovician was subdivided into named conodont zones, whereas the North American Ordovician succession was classified into a series of lettered or numbered faunas. Although most of the latter did not receive zone names until 1984, this classification has been used widely in North America. The Middle and Upper Ordovician Baltoscandic zone classification, which was largely based on evolutionary species changes in lineages and hence includes phylozones, has subsequently undergone only minor changes and has been used slightly modified also in some other regions, such as New Zealand, China and eastern North America. The great importance of conodonts in Ordovician biostratigraphy is shown by the fact that conodonts are used for the definition of two of the seven global stages, and seven of the 20 stage slices, now recognized within this system.
Conodont
Cite
Citations (43)