A new Ordovician rostroconch mollusc from Kazakhstan

The rostroconch mollusc Eopteria aiteneria sp. nov. is described from the Late Ordovician Angrensor Formation of north-eastern Central Kazakhstan; it is the first and only known representative of this group from the Ordovician of central Asia. By the beginning of the Late Ordovician Eopteria and the family Eopteriidae were on the verge of extinction and the new Kazakhstan species represents the youngest preserved record of the family in the Ordovician. It is likely that the group found a refuge in the diverse, but rather conservative, faunal assemblage of the Hiberno-Salairian type associated with Late Ordovician carbonate algal build-ups and mud mounds which spread widely during the late Caradoc to mid Ashgill across Kazakhstanian volcanic island arcs and microplates.     

Ordovician (Bendigonian,Darriwilian to Gisbornian) faunas from the northern Molong Volcanic Belt of central New South Wales

Diverse shallow water assemblages dominated by brachiopods, molluscs, sponges and stromatoporoids, and a tabulate coral, in the Wahringa Limestone Member (Darriwilian-Gisbornian), and Yuranigh Limestone Member (Gisbornian, or early Late Ordovician) of the Fairbridge Volcanics, are documented from the northern Molong Volcanic Belt in central N.S.W. New species described include Billingsaria spissa, Shlyginia printhiensis and Sowerbyites? wahringaensis. Elements of the Wahringa Limestone Member assemblage such as Labechia banksi, Labechiella regularis, and Maclurites cf. M. florentinensis are biogeographically significant in displaying strong similarities with contemporaneous Tasmanian faunas. The brachiopods Ishimia and Shlyginia from the Yuranigh Limestone Member are recognised for the first time outside Kazakhstan and Sibumasu. The presence of the brachiopod Anoptambonites in allochthonous limestone breccia within the lower Fairbridge Volcanics provides evidence of a regionally significant hiatus of 10–15 Ma duration separating this unit from the underlying Hensleigh Siltstone, of Early Ordovician (Bendigonian) age. The sponge Archaeoscyphia?, from allochthonous limestones in the latter formation, is the oldest macrofossil yet described from the Lachlan Fold Belt in central N.S.W.     

Webbygnathus,a new Late Ordovician conodont genus from New South Wales

The new conodont Webbygnathus munusculum gen. et sp. nov. is described from Eastonian (early Late Ordovician) strata from the central part of the Parkes Zone of the Lachlan Fold Belt and the New England Fold Belt in New South Wales. In the type area south of Gunningbland, central New South Wales, the genus occurs associated with macrofossils of the coral/stromatoporoid assemblage Fauna II (early Eastonian or Ea2); in the New England region it has been obtained from strata on both sides of a major structural feature, the Peel Fault, the associated conodont assemblages indicating an age equivalent to that of coral/stromatoporoid assemblage Fauna III or late Eastonian (Ea3). The apparatus of this species, as presently known, comprises two pectiniform elements, one stellate with a four-rayed basal cavity, the other fundamentally pastinate, with a three-rayed basal cavity.     

Late Ordovician cephalopods,tentaculitides, machaeridians and echinoderms from Kuh-e Faraghan,High Zagros,Iran

Ghavidel-Syooki, M., Evans, D.H., Ghobadi Pour, M., Popov, L.E., Álvaro, J.J., Rakhmonov, U., Klishevich, I.A. & Ehsani, M.D., 15.5.2015. Late Ordovician cephalopods, tentaculitides, machaeridians and echinoderm columnals from Kuh-e Faraghun, High Zagros, Iran. Alcheringa 39, 530–549. ISSN 0311-5518.

Late Ordovician (Katian, uppermost Acanthochitina barbata to Armoricochitina nigerica chitinozoan zones) cephalopods, tentaculitides, machaeridians and echinoderms are documented for the first time from the southern Zagros Ranges. A low-diversity cephalopod fauna includes Geisonocerina dargazense sp. nov., Isorthoceras sp. cf. I. bisignatum (Barrande) and other undetermined orthoceratides. The presence of Late Ordovician tentaculitides in the high- to mid-latitude margins of Gondwana has been documented previously, but no examples have been described in detail. Thus, Costatulites kimi sp. nov., which currently occurs associated with brachiopods characteristic of the Svobodaina havliceki (brachiopod) Association, represents the earliest undoubted record of tentaculitides in Gondwana. Machaeridians constitute a relatively common component of the Late Ordovician benthic faunas from the Mediterranean margin of Gondwana, but no previous records on the Gondwanan Iranian-Arabian segment have been reported. Three echinoderm taxa based on dissociated columnals are documented from the Armoricochitina nigerica chitinozoan Zone, including Sumsaricystis radiatus Stukalina, Ristnacrinus sp. and Rosulicrinus rosulus Stukalina.

Mohammad Ghavidel-Syooki [m_ghavidelsyooki@yahoo.com] Institute of Petroleum Engineering, Technical Faculty of Tehran University, PO Box 11365-4563, Tehran, Iran; David H. Evans [david.evans@naturalengland.org.uk], Natural England, Suite D, Unex House, Bourges Boulevard, Peterborough PE1 1NG, UK; Mansoureh Ghobadi Pour* [mghobadipour@yahoo.co.uk], Department of Geology, Faculty of Sciences, Golestan University, Gorgan, Iran; Leonid E. Popov [leonid.popov@museumwales.ac.uk], Department of Geology, National Museum of Wales, Cathays Park, Cardiff CF10 3NP, UK; J. Javier Álvaro [jj.alvaro@csic.es], Instituto de Geociencias (CSIC-UCM), c/ José Antonio Novais 2, 28040 Madrid, Spain; Utkyr Rakhmonov, Kitab State Geological Reserve, 9 Ipak Yuli Street, Sakhrisabz, Uzbekistan; Inna A. Klishevich, Department of Historical Geology, Geological Faculty, St Petersburg State University, Universitetskaya Naberezhnaya 7/9, 199034 St Petersburg, Russia [inna@IK4848.spb.edu]; Mohammad H. Ehsani [mh_ehsani@hotmail.com], Institute of Petroleum Engineering, Technical Faculty of Tehran University, PO Box 11365-4563, Tehran, Iran. *Also affiliated with Department of Geology, National Museum of Wales, Cathays Park, Cardiff CF10 3NP, UK.     

The oldest Ordovician stromatoporoids from Australia

The oldest known Australian Ordovician stromatoporoids are described from the Cashions Creek Limestone (formerly the Maclurites-Girvanella horizon) and correlatives of the Gordon Subgroup in Tasmania. The Cashions Creek Limestone and equivalents are correlated approximately with the North American Chazyan (Middle Ordovician). Representatives of Labechia, Stratodictyon and Stromatocerium are recorded from localities in the Mole Creek area, from the Florentine Valley and from Melrose. Three new species, Labechia banksi, Stratodictyon vetus and Stromatocerium bigsbyi are described. L. banksi comes from a slightly higher horizon in the succession at Mole Creek where it occurs in association with the earliest corals (Lichenaria). The distribution of the earliest Ordovician stromatoporoids — those appearing in the North American and Tasmanian successions — is reviewed, together with a discussion of their possible origins and interrelationships.     

Palaeobiogeography of the Ordovician trilobite Prosopiscus,with a new species from western New South Wales

Prosopiscus is particularly important in Ordovician palaeobiogeography because of its wide geographic distribution in Gondwana and peri-Gondwanan regions. It appears to have been confined to low palaeolatitudes, representing a characteristic member of the warm water eastern Gondwanan shelf faunas. Trends in the distribution of the Ordovician genus can be observed due to its long stratigraphic range. Prosopiscus was restricted to, and may have originated in, Australia during the late Early Ordovician (Bendigonian-Chewtonian). By the Middle Ordovician (Darriwilian), Prosopiscus had dispersed to other parts of Gondwana and peri-Gondwana, including the North and South China blocks, Tarim, central Himalayas, and the Argentine Precordillera (South America). Possible explanations for the distribution of Prosopiscus are that: (1) there were no oceanic barriers preventing dispersal of trilobites between different regions of Gondwana, thus permitting uninhibited migration over vast distances; (2) Prosopiscus was not restricted to a specific biofacies; (3) a major eustatic transgression during the early Darriwilian may have facilitated the dispersal of Prosopiscus in allowing further development and expansion of marine environments; and (4) a prolonged planktonic larval stage may have permitted wide dispersal.

Prosopiscus lauriei sp. nov. is described from the late Early Ordovician (Bendigonian-Chewtonian) Tabita Formation at Mount Arrowsmith, northwestern New South Wales, Australia. The new species is closely related to P. praecox, from the Nora Formation, Georgina Basin, central Australia, and to P. magicus from northwest China.     

Trilobites from the Middle Ordovician Stairway Sandstone,Amadeus Basin,central Australia

Abstract

During the Middle Ordovician (Darriwilian) sandstones and siltstones were deposited in the epicontinental Larapintine Sea, which covered large parts of central Australia. The Darriwilian Stairway Sandstone has, for the first time, been sampled stratigraphically for macrofossils to track marine benthic biodiversity in this clastic-dominated shallow-water palaeoenvironment situated along the margin of northeastern Gondwana. The faunas from the Stairway Sandstone are generally of low diversity and dominated by bivalves but include several animal groups, with trilobites representing 25% of the entire shelly fauna. Thirteen trilobite taxa are described from the Stairway Sandstone; the fauna displays a high degree of endemism. One new species, Basilicus (Parabasilicus) brumbyensis sp. nov. is described.     

A possible hydroid from the Lower and Middle Ordovician of Bohemia

A new genus Webbyites from the Lower and Middle Ordovician of Bohemia is described. Its planar, feather-like benthic colonies (or their parts) display possible hydrozoan affinites. Webbyites is interpreted as an inhabitant of the littoral and sublittoral environment, with high energy, oscillating to current zones.     

Early Ordovician conodonts from Zhejiang Province,southeast China and their biostratigraphic and palaeobiogeographic implications

Forty-two conodont species are documented from the Liuxia, Shijiatou and Jingshan formations in Zhejiang Province of southeast China, located palaeogeographically on the Jiangnan Slope offshore to the Yangtze Platform. From these faunas, eight successive conodont biozones of Tremadocian to middle Floian (Early Ordovician) age are recognized, including the Cordylodus lindstromi Biozone, Cordylodus angulatus Biozone, Chosonodina herfurthi Biozone, Paltodus deltifer Biozone, Paroistodus proteus Biozone, Triangulodus bifidus Biozone, Serratognathus diversus Biozone and Prioniodus elegans Biozone. Several zonal index species of the Baltoscandian succession—Paltodus deltifer, Paroistodus proteus and Prioniodus elegans—are described and illustrated in detail for the first time from South China. Co-occurrence of P. proteus and Serratognathus bilobatus in several samples below the appearance of P. elegans also confirms correlation of the S. diversus Biozone (basal Floian) with the upper P. proteus Zone of the Baltoscandian succession. These Zhejiang faunas are dominated by pandemic forms, and are similar to those of the Open-Sea Realm elsewhere, inhabiting deep, offshore environments.     

Revision of two phragmodontid species (Conodonta) from the Darriwilian (Ordovician) of the Canning Basin in Western Australia and phylogeny of the Cyrtoniodontidae

Zhen, Y.Y. 9 July 2019. Revision of two phragmodontid species (Conodonta) from the Darriwilian (Ordovician) of the Canning Basin in Western Australia and phylogeny of the Cyrtoniodontidae. Alcheringa XX, xxx–xxx. ISSN 0311-5518

Based on re-examination of the material used in the original study from the subsurface Goldwyer and Nita Formations (middle Darriwilian, Middle Ordovician) of the Canning Basin, Western Australia, two phragmodontid species (Phragmodus polystrophos Watson and Ph. spicatus Watson) are revised as having a septimembrate apparatus including geniculate (Ph. polystrophos) or nongeniculate (Ph. spicatus) M, triform alate Sa, modified tertiopedate (Ph. polystrophos) or tripennate (Ph. spicatus) Sb, modified bipennate Sc, modified quadriramate Sd, carminate Pa and pastinate Pb elements. Characterized by a carminate Pa element in their respective species apparatuses, these two species demonstrate a close phylogenetic relationship with Phragmodus cognitus Stauffer from the Late Ordovician (Sandbian) of North America. These distinctive shared characters have allowed their accommodation within a new genus, Protophragmodus gen. nov., which represents an evolutionary lineage separated from species of Phragmodus Branson & Mehl (sensu stricto). In addition, it is postulated that the Cyrtoniodontidae might have originated in the early–middle Darriwilian from ‘Plectodina’ in shallow-water settings, with Phragmodus (sensu stricto), the most derived part of the family, perhaps directly evolving from Protophragmodus gen. nov. in the late Darriwilian and then becoming cosmopolitan, deeper-water dwellers in the Late Ordovician.

Y.Y. Zhen [yong-yi.zhen@planning.nsw.gov.au], Geological Survey of New South Wales, W.B. Clarke Geoscience Centre, 947–953 Londonderry Road, Londonderry, NSW 2753, Australia.     

Devonian trilobites from the Shogrām Formation,Kurāgh,Chitral (NW Pakistan)

Late Devonian trilobites from horizons close to the Frasnian-Famennian boundary in the Shogrām Formation at Kurāgh, Chitral (NW Pakistan) are described. A new species of Asteropyginae, Neocalmonia chitralensis sp. nov., and a new subpecies, Neocalmonia batillifera orientalis subsp. nov., are described; these extend the range of Asteropyginae eastwards from Iran and southern Afghanistan. The Upper Kellwasser Event is located within KUR 19 of Talent et al. (1999).     

A new Llanvirnian Isograptus from the D. murchisoni Shales of Abereiddy Bay,Wales

Isograptus ovatus davidensis subsp. nov. is described from the D. murchisoni Shales of Abereiddy Bay, Wales. This discovery gives further support to the correlation of the murchisoni Zone with the upper part of the Darriwil Stage of Victoria.     

The early bivalve radiation in the Ordovician Gondwanan basins of Argentina

The Ordovician diversification is marked by an increase in both marine diversity and ecospace occupation. Bivalves, like other groups, underwent a remarkable diversification in the Early Ordovician. The early phases of such a bivalve diversification took place in the Gondwanan basins of western Argentina. In the Northwestern Argentina (NWA) Basin, three clades originated during late Tremadocian–Floian times. In the Floian successions of the Famatina Basin, a probable basal arcoid is recorded. Genera from these two basins belong to 13 families. Phylogenetic analysis of the NWA heteroconchian bivalves indicates that redoniids and coxiconchinids may have originated during this radiation event. This taxonomic radiation also implies an ecological diversification. Ten guilds are recognized on the basis of bauplan, mode of life, and feeding types. Lifestyles included free endofaunal, free semi-endofaunal, semi-endobyssate, and epibyssate; feeding types included suspensivorous and detritivorous habits. Physiological changes imposed by colonization of low-salinity environments also account for guild definitions. Recent discoveries of Tremadoc to early Darriwilian bivalves from the NWA and Famatina basins indicate that the dominance of higher groups (e.g. Heteroconchia, Pteriomorphia) deviates from the patterns evident in other Gondwanan basins. This agrees with previous ideas supporting the importance of local radiations during the Ordovician diversification. Two new taxa are described, Eoredonia orientalis gen. et sp. nov. and Babinka notica sp. nov., and Coxiconchia sellaensis Sánchez & Babin is first reported from the NWA Basin.     

Ordovician trilobites from Deh-Molla,eastern Alborz,Iran

Ghobadi Pour, M., 21 June 2019. Ordovician trilobites from Deh-Molla, eastern Alborz, Iran. Alcheringa 43, 381–405. ISSN 0311-5518

Seventeen species from 14 genera of Tremadocian and Darriwilian trilobites, plus two taxa recognizable only down to family level, have been documented from the Lower to Middle Ordovician succession of the Deh-Molla area, southeast of Shahrud in northern Iran. Two species, Asaphellus intermedius and Conophrys multituberculatus, are new to science. Unlike previously documented Iranian faunas, the early Tremadocian trilobite assemblage is characterized by proliferation of the olenid Chungkingaspis sinensis, which is also known as the eponymous taxon of the basal Ordovician trilobite biozone in South China. This is the first record of the occurrence of the olenid biofacies in the Ordovician of Iran. Overall, both the Tremadocian and Darriwilian trilobite assemblages show distinct similarity to the contemporaneous faunas of South China down to species level. Trilobite-based correlation with the Ordovician succession of South China confirms the existence of a hiatus at the base of the Ordovician succession in the eastern Alborz and a significant gap, with the upper Tremadocian, Floian and Dapingian parts of the succession completely missing in Deh-Molla.

Mansoureh Ghobadi Pour [mghobadipour@yahoo.co.uk and m.ghobadipour@gu.ac.ir], Department of Geology, Faculty of Sciences, Golestan University, Gorgan 49138-15739, Iran. *Also affiliated with Department of Natural Sciences, Natural Museum of Wales, Cardiff, Cathays Park, Cardiff CF10 3NP, UK.     

High latitude,late Campanian (Cretaceous) Radiolaria from offshore south-eastern Tasmania

A well-preserved, low diversity (ten species), high latitude (palaeolatitude 70°S) radiolarian fauna is recorded from shallow-water late Campanian (Late Cretaceious) sediments recovered in cores taken from the continental slope of southeastern Tasmania. These are the first Radiolaria described from Cretaceous rocks of southeastern Australia. Most forms are previously described species but a new species of Petasiforma is described. Age control is provided by dinoflagellates but the radiolarian fauna is similar to late Campanian-Maastrichtian faunas described from Campbell Plateau. A late Campanian age can also be determined from the Radiolaria, which are correlated with the Patulibracchium dickinsoni Zone. The site has subsided some 3200 m since deposition, at an average rate of about 40–45 m/Ma, consistent with other indicators in the region. Radiolaria are similar to other coeval plankton in exhibiting high latitude characteristics.     

New,early ostracods from the Ordovician (Tremadocian) of Iran: systematic,biogeographical and palaeoecological significance

New Tremadocian ostracod material from the Alborz Mountains of Iran confirms the early and widespread occurrence of the Ordovician genus Nanopsis, and the apparently simultaneous first appearance of ostracods in the fossil record at the level of the P. deltifer conodont biozone (485.5 Ma) from China to Argentina. Nanopsis pairidaeza sp. nov. adds to the pool of species diversity for the Early Ordovician, though documented Tremadocian ostracod generic diversity remains low, with only four genera. The presence of Early Ordovician ostracods in Alborz, their occurrence elsewhere in palaeocontinental Gondwana, Baltica and China coupled to their marked absence from the Tremadocian of Laurentia and Siberia, supports the notion of the earliest occurrence of ostracods centred on Gondwana/Baltica.     

The Late Palaeozoic brachiopod genus Jakutoproductus Kashirtsev 1959 and the Jakutoproductus verchoyanicus Zone,northern Yukon Territory,Canada

Shi, Guang R., 1994:03:28. The Late Palaeozoic brachiopod genus Jakutoproductus Kashirtsev 1959 and the Jakutoproductus verchoyanicus Zone, northern Yukon Territory, Canada. Alcheringa 18, 103–120. ISBN 0311-5518.

The familial and subfamilial position, species composition, and geographic distribution of the Late Palaeozoic productid genus Jakutoproductus Kashirtsev 1959 are reviewed. Jakutoproductus is placed in the subfamily Plicatiferinae Muir-Wood & Cooper 1960 of the family Plicatiferidae. Eighteen described species from the Russian Arctic. Mongolia, northeast China, and northern Yukon Territory, Canada are assigned to Jakutoproductus. The Jakutoproductus verchoyanicus Zone of late Sakmarian to Artinskian age, most likely early Artinskian (Aktastinian), here established is based on material from the Jungle Creek Formation, northern Yukon Territory, Canada, and is correlated with the following horizons in Russia: the Osennin Horizon in the Verchoyan Mountains, the lower Munugudjak Horizon of the Kolyma-Omolon Massif, the Hipkhoshin Suite of east Zabaikal, the lower Bhang Horizon of Taimyr, and an unnamed sandstone-shale unit on the north island of Novaya Zemlya.     

Ichnofacies of the Stairway Sandstone fish-fossil beds (Middle Ordovician,Northern Territory,Australia)

The Stairway Sandstone is a 30–560 m thick succession of Middle Ordovician siliciclastic sedimentary rocks within the Amadeus Basin of central Australia, deposited in the epeiric Larapintine Sea of northern peri-Gondwana. The Stairway Sandstone is significant as one of only two known Gondwanan successions to yield articulated arandaspid (pteraspidomorph agnathan) fish. Herein we use the ichnology of the Stairway Sandstone to reveal insights into the shallow marine habitat of these early vertebrates, and compare it with that of other known pteraspidomorph-bearing localities from across Gondwana. The Stairway Sandstone contains a diverse Ordovician ichnofauna including 22 ichnotaxa of Arenicolites, Arthrophycus, Asterosoma, Cruziana, Didymaulichnus, Diplichnites, Diplocraterion, ?Gordia, Lockeia, Monocraterion, Monomorphichnus, Phycodes, Planolites, Rusophycus, Skolithos and Uchirites. These ichnofauna provide a well-preserved example of a typical Ordovician epeiric sea assemblage, recording the diverse ethologies of tracemakers in a very shallow marine environment of flashy sediment accumulation and regularly shifting sandy substrates. New conodont data refine the age of the Stairway Sandstone to the early Darriwilian, with ichnostratigraphic implications for the Cruziana rugosa group and Arthrophycus alleghaniensis.     

Conodont fauna and biostratigraphy of the Honghuayuan Formation (Early Ordovician) of Guizhou,South China

Serratognathus diversus An, Cornuodus longibasis (Lindström), Drepanodus arcuatus Pander, and eleven other less common conodonts, including Cornuodus? sp., Oistodus lanceolatus, Protopanderodus gradatus, Protoprioniodus simplicissimus, Juanognathus variabilis, Nasusgnathus dolonus, Paltodus? sp., Scolopodus houlianzhaiensis, Semiacontiodus apterus, Semiacontiodus sp. cf. S. cornuformis and Serratognathoides? sp., are described and illustrated from the Honghuayuan Formation in Guizhou, South China, concluding revision of the conodont fauna from this unit, which comprises 24 species in total. The most distinctive species in the fauna, S. diversus, consists of a trimembrate apparatus, including symmetrical Sa, asymmetrical Sb and strongly asymmetrical Sc elements. This species concept is supported by the absence of any other element types in a large collection represented by nearly 500 specimens of this species. The fauna indicates a late Tremadocian to mid-Floian age (Early Ordovician) for the Honghuayuan Formation, which was widely distributed on the Yangtze Platform in shallow water environments. Previously published biostratigraphic zonations for the Honghuayuan Formation are reviewed, and revised on the basis of our knowledge of the entire conodont fauna, supporting the establishment of three biozones, Triangulodus bifidus, Serratognathus diversus, and Prioniodus honghuayanensis biozones in ascending order. Species of Serratognathus enable correlation between Ordovician successions of South China, North China (North China Platform and Ordos Basin), Tarim Basin, and further afield into Malaysia and northwestern Australia.     

Palaeontology of the Cerros Bayos section,Roca Formation (Danian), La Pampa Province,Argentina

Palynofloras from an outlier of Tertiary sediments in the One Tree Hill area north of Adelaide are nonmarine and correlate with similar assemblages from Middle Eocene North Maslin Sands from Maslin Bay and Golden Grove. Although there are similarities with time-equivalent Lower Nothofagidites asperus Zone palynofloras in the Gippsland Basin, a number of species in the South Australian palynofloras do not extend below the Late Eocene in the Gippsland sequences. This indicates earlier appearances for these species in southcentral Australia. The sediments overlie a highly weathered bedrock palaeosurface, indicating that a phase of significant weathering occurred prior to the Middle Eocene. A number of selected taxa are illustrated and their distribution in the palynofloras is discussed. Two new species, Proteacidites mildenhallii and Proteacidites parrawirrensis, are described and one species, Rhoipites byfieldensis, is emended.