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.     

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

Jakobsen, K.G., Brock, G.A, Nielsen, A.T., Topper, T.P. & Harper, D.A.T., 2013. Middle Ordovician brachiopods from the Stairway Sandstone, Amadeus Basin, central Australia. Alcheringa. ISSN 0311–5518.

Middle Ordovician brachiopod faunas from the Amadeus Basin, central Australia are poorly known. The Darriwilian Stairway Sandstone was sampled stratigraphically for macrofossils in order to provide new information on marine benthic diversity in this clastic-dominated, shallow-water palaeoenvironment along the margin of northeastern Gondwana. The brachiopods from the Stairway Sandstone are of low diversity and represent ca 9% of the entire shelly fauna. Five brachiopod taxa are described from the Stairway Sandstone; all are endemic to the Amadeus Basin at species level. Two new species, Amadeuphyla joanae gen. et sp. nov. and Paralenorthis luritjaorum sp. nov., are described. Unweighted cladistic analysis based on 20 characters places the new genus Amadeuphyla within the Taffinae.

Kristian G. Jakobsen [kgjakobsen@snm.ku.dk] Geological Museum, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5–7, DK-1350 Copenhagen, Denmark & Department of Biological Sciences, Macquarie University, New South Wales 2109, Australia. Glenn A. Brock [glenn.brock@mq.edu.au] Department of Biological Sciences, Macquarie University, New South Wales 2109, Australia. Arne T. Nielsen [arnet@snm.ku.dk] Geological Museum, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5–7, DK-1350 Copenhagen, Denmark. Timothy P. Topper [timothy.topper@snm.ku.dk] Geological Museum, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5–7, DK-1350 Copenhagen, Denmark. David A. T. Harper [david.harper@durham.ac.uk] Geological Museum, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5–7, DK-1350 Copenhagen, Denmark & Department of Earth Sciences, Durham University, Durham, UK. Received 14.6.2013; revised 25.9.2013; accepted 8.10.2013.     

Ordovician trilobite faunas and depositional history of the Taebaeksan Basin,Korea: implications for palaeogeography

The Taebaeksan Basin occupies the central-eastern part of the Korean peninsula and was a low-relief shallow marine carbonate shelf on which the Cambro-Ordovician Choson Supergroup was deposited. In the Taebaeksan Basin trilobites are among the most dominant fossil groups in the Lower Ordovician, but they become less important in Middle Ordovician faunal assemblages. The Early Ordovician trilobite faunas of the Taebaeksan Basin are characterised by the common occurrence of pandemic genera such as Jujuyaspis, Leiostegium, Asaphellus, Protopliomerops, Hystricurus, Apatokephalus, Shumardia, Asaphopsoides, and Kayseraspis. Biogeographically significant trilobite taxa include Yosimuraspis, Dikelokephalina, Koraipsis, and Chosenia. These Ordovician trilobite faunas, which thrived in shallow marine environments, show a remarkable similarity with faunas from North China, implying that the Taebaeksan Basin was connected through contiguous shallow waters to North China. These Sino-Korean faunas exhibit a close biogeographic connection with Australian faunas, with which they share some endemic genera, whereas they are more distantly related to the faunas of South China, South America, and North America. Based on these palaeobiogeographical features, it is suggested that in the early Palaeozoic much of the present Korean peninsula including the Taebaeksan Basin belonged to the Sino-Korean block, while part of the peninsula was derived from the Yangtze block.     

A late Miocene–early Pliocene Mihirung bird (Aves: Dromornithidae) from Victoria,southeast Australia

Park, T. & Fitzgerald, E.M.G. September 2012. A late Miocene–early Pliocene Mihirung bird (Aves: Dromornithidae) from Victoria, southeast Australia. Alcheringa 36, 427–430. ISSN 0311-5518.

An incomplete tarsometatarsus identified as an indeterminate species of Dromornithidae is described from the upper Miocene–lower Pliocene shallow marine Black Rock Sandstone at Beaumaris, Victoria, Australia. This isolated specimen represents one of the few pre-Pleistocene dromornithids with a well-constrained geologic age. Additionally, it is one of the few pre-Quaternary dromornithid fossils recorded from southeast Australia. Comparisons with known dromornithid taxa suggest that the Beaumaris dromornithid is distinct from previously established species. This hitherto unknown species of dromornithid in the late Neogene of southeastern Australia cautions against deriving evolutionary patterns solely on the basis of fossils from northern Australia.     

Middle Cambrian to Lower Ordovician faunas from the Chingiz Mountain Range,central Kazakhstan

Tolmacheva, T.JU., Degtyarev, K.E., Samuelsson, J. & Holmer, L.E., December, 2008. Middle Cambrian to Lower Ordovician faunas from the Chingiz Mountain Range, central Kazakhstan. Alcheringa 32, 443–463. ISSN 0311-5518.

The middle Cambrian to Lower Ordovician back-arc sedimentary succession studied in the Kol'denen River and in the Zerbkyzyl Mountains of the central Chingiz Mountain Range is composed predominantly of siltstones, sandstones and volcaniclastic rocks with rare beds of micritic carbonates, black shales and cherts. Fossil assemblages including conodonts, lingulate brachiopods, arthropods, sponges and probable Tasmanites cysts were recorded both from the carbonate and chert beds showing that richly diverse marine environments existed directly adjacent to the volcanic arcs. The Kol'denen River localities contain a diverse upper Cambrian paraconodont assemblage of the open-sea affinity. The representatives of Rossodus, Cordylodus, Drepanodus and Variabiloconus, having an almost pandemic distribution and characteristic of basinal facies, dominate the Lower Ordovician conodont fauna. The Cambrian–Ordovician boundary transition is characterized by chert production that was more likely caused by a local productivity increase than by general changes in palaeooceanographic and palaeogeographical conditions.     

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.     

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.     

A palynological investigation of plesiosaur-bearing rocks from the Upper Cretaceous Tahora Formation,Mangahouanga, New Zealand

High-palaeolatitude plesiosaur, mosasaur and, more rarely, dinosaur fossils are well known from the Maungataniwha Sandstone Member of the Tahora Formation in Mangahouanga Stream, Hawkes Bay, New Zealand. A palynological investigation of strata exposed along Mangahouanga Stream and of transported boulders hosting vertebrate fossils reveals well-preserved assemblages dominated by terrestrial pollen and spores but also including marine dinoflagellate cysts in some samples. The palynofacies are strongly dominated by wood fragments including charcoal; one outcrop sample and the sample taken from a boulder hosting plesiosaur vertebrae contain entirely terrestrially derived palynoassemblages, suggesting a freshwater habitat for at least some of the plesiosaurs. The host unit spans the Santonian to lowermost Maastrichtian, while the key pollen taxa Nothofagidites senectus and Tricolpites lilliei, together with the dinocyst Isabelidinium pellucidum and the megaspore Grapnelispora evansii, indicate a late Campanian to early Maastrichtian age for the fossiliferous boulders. The palynoflora indicates a mixed local vegetation dominated by podocarp conifers and angiosperms with a significant tree-fern subcanopy. The presence of taxa with modern temperate distributions, such as Nothofagus (southern beech), Proteaceae and Cyatheaceae (tree-ferns), indicates a mild-temperate climate and lack of severe winter freezing during the latest Cretaceous, providing an ecosystem that most probably made it possible for polar dinosaurs to overwinter in this part of the world.     

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.     

Oligocene-Miocene palynomorphs from subsurface sediments,West Bengal,India

Palynological studies of Cenozoic sediments from borehole PGD-1A in the easternmost extension of the Damodar Basin, West Bengal, India, provide important new palynological data from this basin, where previous data are rare. The palynoassemblage includes Striatriletes, Crassoretitriletes, Bacutriporites, Cauveripollis, Cheilanthoidspora, Palaeomalvaceaepollis, Tricollareporites, Pinuspollenites and Tsugaepollenites which suggest a late Oligocene - early Miocene age. Dinocyst genera such as Selenopemphix, Tuberculodinium, Hystrichokoipoma and Thalasiphora, recorded from the borehole, also support this age assignment. The assemblage indicates a tropical to subtropical humid climate with high rainfall. Deposition of the studied strata took place in a delta under shallow marine influence; this is the first evidence that a marine transgression extended into the Damodar Basin and that mangrove forest developed in the area.     

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.     

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.     

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 radiation of early Silurian spiriferide brachiopods,with new taxa from the Llandovery of Iran

Popov, L.E. & Cocks, L.R.M., 2013. The radiation of early Silurian spiriferide brachiopods, with new taxa from the Llandovery of Iran. Alcheringa 38, 560–566. ISSN 0311–5518.

Although there were Late Ordovician spiriferides in the superfamily Cyrtioidea, namely Eospirifer and Odakella, only the former genus survived the terminal Ordovician extinction, and only Eospirifer is known from the earliest Llandovery (Rhuddanian). However, in the succeeding mid-Llandovery (Aeronian), the spiriferides radiated to include not only more species within Eospirifer and Striispirifer in the Eospiriferidae, but also the new genus Iranospirifer described here, which is the earliest representative of the other family within the superfamily, the Hedeinopsidae. The Ordovician species were confined to the South China continent and the Boshchekul volcanic island arc in Kazakhstan, but by the Aeronian the superfamily had spread westwards to various other continents, including the main Gondwanan superterrane (which included Iran) in the early Aeronian, and Avalonia-Baltica and Laurentia in the late Aeronian. The new species Eospirifer ghobadiae and Iranospirifer qarabilensis are both described from the lower Aeronian of Iran, and there is a note on the Aeronian rhynchonellide Stegocornu, which is endemic to Iran and nearby areas.

Leonid E. Popov [lepbarry@yahoo.co.uk; leonid.popov@museumwales.ac.uk] Department of Geology, National Museum of Wales, Cathays Park, Cardiff CF10 3NP, UK. L. Robin M. Cocks [r.cocks@nhm.ac.uk], Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK. Received 29.5.2013, revised 12.7.2013, accepted 21.7.2013.     

Cretaceous foraminiferal biostratigraphy of Queensland

The distribution of foraminiferids within Aptian-Albian marine deposits of the Laura, Carpentaria, Eromanga, and Surat Basins in Queensland is described. The foraminiferal distribution patterns are largely a reflection of environmental differences which existed within the basins. Among the benthonic foraminiferids, two major faunal associations are recognized: the Ammobaculites association reflecting hyposaline, cool, shallow water conditions; and the Marssonella association indicating normal marine, open continental shelf environments. As the faunal content of these associations is markedly different, separate time-stratigraphic zonations are proposed: the Ammobaculites association is divided into the Textularia cushmani zone (early Aptian), T. cushmani-Bigenerina pitmani zone (late Aptian), B. pitmani zone (late Aptian), B. pitmani-Riyadhella crespinae zone (early Albian), and R. crespinae zone (early-late Albian); the Marssonella association contains the Anomalinoides intermedia zone (early-middle Albian in Queensland), and the A. cenomanica zone (late Albian in Queensland). Planktonic foraminiferids, which occur with both benthonic associations, are used to correlate the benthonic zonal schemes, and are themselves zoned separately: Hedbergella planispira zone (early-middle Albian), H. infracretacea zone (middle-early late Albian), and the H. delrioensis zone (late Albian). International stage correlations are based on certain foraminiferids and associated ammonites.

The distribution of foraminiferids in Queensland during the late Early Cretaceous suggests that 1, climate exerted a uniform influence over the region; 2, cool, hyposaline, shallow water conditions prevailed over much of Queensland; 3, open marine shelf conditions (of normal salinity) existed during the Albian in the Laura and northeastern Carpentaria Basins; and 4, during the Albian, at least, there was a northern seaway to the open ocean.     

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.     

A late Miocene–early Pliocene baleen whale assemblage from Langebaanweg,west coast of South Africa (Mammalia,Cetacea, Mysticeti)

Govender, R., Bisconti, M. & Chinsamy, A., June 2016. A late Miocene–early Pliocene baleen whale assemblage from Langebaanweg, west coast of South Africa (Mammalia, Cetacea, Mysticeti). Alcheringa 40, xxx–xxx. ISSN 0311-5518

Knowledge of post-Eocene cetaceans from Africa is very poor with almost nothing known about this group from southern Africa except for the diverse trawled ziphiids. Langebaanweg, a locality yielding prolific Miocene–Pliocene fossils on the southwestern Cape coast of South Africa, preserves terrestrial and marine biotas in juxtaposition. Palaeoenvironments vary from a marine shoreline to a lagoon and estuary and later a shallow marine environment and include several microhabitats. Fragmentary preservation of the cetacean skeletons suggests that they were transported before burial. This first detailed analysis of the Mio-Pliocene mysticete fossils from Langebaanweg uses the petrotympanic region to taxonomically identify specimens. Three un-named species of balaenopterid Mysticeti represent a Plesiobalaenoptera-like form, but it is premature to erect a new taxon based on this fragmentary material. The remaining material is too poorly preserved to be identified with confidence.

Romala Govender [rgovender@iziko.org.za], Natural History Department, Iziko Museums of South Africa, PO Box 61, Cape Town, 8001, South Africa; Biological Sciences, University of Cape Town, Private Bag X3, Rhodes Gift, 7701, Cape Town, South Africa, Michelangelo Bisconti [michelangelobisconti@gmail.com], Natural History Museum of San Diego, California, 1788 El Prado, San Diego, CA 92101, USA; Anusuya Chinsamy [anusuya.chinsamy-turan@uct.ac.za], Biological Sciences, University of Cape Town, Private Bag X3, Rhodes Gift, 7701, Cape Town, South Africa.     

Phylogenetic relationships of leptellinid brachiopods

The relationships among the diverse genera comprising the family Leptellinidae (Brachiopoda) are reviewed in the light of the revised edition of the Treatise on Invertebrate Palaeontology. Taxonomic work reassessed all the genera identified as Leptellinidae in the most current classification. Four genera were discarded, namely Bekkerella, Benignites, Leptastichidia and Nikitinamena. Cladistic analysis reveals the paraphyly of these genera; their abandonment leading to more morphologically coherent subdivisions of the family. Two subfamilies, Leptellininae and Palaeostrophomeninae, are emended and taxonomically restructured. The palaeogeographical history of the Leptellinidae is complicated. The Leptellinidae are first recorded in Baltica in the late Floian (Early Ordovician) and rapidly dispersed to circum-Iapetus palaeocontinents by the Dapingian, thence to most terranes composing Gondwana by the Darriwilian (Middle Ordovician).     

Late Devonian thelodonts (Agnatha) from the Gneudna Formation,Carnarvon Basin,Western Australia

Dermal denticles of two thelodont agnathans, Australolepis seddoni gen. et sp. nov., and a possible nikoliviid gen. et sp. indet. are described from the Gneudna Formation, a marine sequence of interbedded limestone and shale exposed on the eastern edge of the Carnarvon Basin, Western Australia. The age and significance of these new forms are discussed. The Gneudna Formation is Late Devonian, probably early Frasnian, which, if confirmed, makes these the youngest thelodonts known to date.