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.     

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.     

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.     

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.     

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.     

The graptolite Glossograptus Emmons and its proximal structure

Ni Yunan & Cooper, R. A., 1994:03:28. The graptolite Glossograptus Emmons and its proximal structure. Alcheringa 18, 161–167. ISSN 0311-5518.

New specimens of Glossograptus acanthus from the Ningkuo Shale of China, preserved in relief, help to resolve the much debated problem of the structure of Glossograptus. A model for the proximal structure of the genus is proposed, based on the new material and on Finney's (1978) Athens Shale specimens. The model confirms that Glossograptus has homologous structure and development with Pseudisograptus, and isograptid development type is primitive for the group containing both genera. A cladogram is presented in which the suborder Glossograptina Jaanusson (with families Glossograptidae and Cryptograptidae) together with family Corynoididae Bulman are subsumed within a redefined family Glossograptidae.     

Graptolite fauna of the Hungshihyen Formation (Early Ordovician), eastern Yunnan,China

Ordovician graptolite-bearing strata in eastern Yunnan were deposited in nearshore, shallow-water environments. Graptolites are systematically described from three sections through the Hungshihyen Formation in eastern Yunnan Province, China: (1) Hongshiya section near Ercun village, Kunming; (2) Liujiang section, Luquan; and (3) Guihuaqing Reservoir section, Luquan. The graptolite fauna, characterized by the predominance of deflexed forms, includes ten species in two genera: Baltograptus turgidus (Lee), B. varicosus (Wang), B. yunnanensis (Li), B. calidus (Ni), B. enshiensis (Ni), Baltograptus sp. cf. B. deflexus (Elles & Wood), Baltograptus sp. cf. B. bolivianus (Finney & Branisa), Baltograptus sp. A, Baltograptus sp. B and Corymbograptus v-fractus minor (Li). A detailed morphological study of these southern Chinese graptolite faunas suggests that Baltograptus wudingensis (Li) is a junior synonym of B. turgidus (Lee); Baltograptus kunmingensis (Ni) is a junior synonym of B. varicosus (Wang); and Baltograptus triangulatus (Ni) is a junior synonym of B. yunnanensis (Li). The B. varicosus Biozone is newly recognized within the middle part of the Hungshihyen Formation, replacing the former Didymograptus deflexus Biozone. This interval is well correlated to the Baltograptus jacksoni Biozone in Britain, the Tetragraptus akzharensis, ‘Baltograptus cf. deflexus’ and Didymograptus bifidus (lower part) biozones in NW Argentina (eastern Cordillera), and the Acrograptus filiformis and Didymograptellus eobifidus biozones in northern Guizhou, South China. Accordingly, the interval is of mid-Floian age, rather than late Floian as previously proposed.     

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.     

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.     

Assignment of the South Chinese Ordovician trilobite Calymene paronai to Neseuretus

Turvey, S.T. & Siveter, D.J., June 2007. Assignment of the South Chinese Ordovician trilobite Calymene paronai to Neseuretus. Alcheringa 31, 173‐183. ISSN 0311-5518.

Calymene paronai Pellizzari, 1913 Pellizzari, G. 1913. Fossili Palaeozoici antichi dello Scensi (Cina). Rivista Italiana di Palaeontologia, 19: 33–47.  [Google Scholar] was described on the basis of an almost complete enrolled specimen from the Ordovician (probably the early Llanvirn Yangtzeella poloi Biozone) of southern Shaanxi, China. It represents one of the first Chinese trilobite species to have been established, but has been almost completely ignored by subsequent workers. This species is redescribed and reassigned to the Gondwanan inner shelf indicator calymenid Neseuretus, compared with other South Chinese taxa previously assigned to this genus, and interpreted as a senior synonym of N. concavus Lu, 1975 Lu, Yanhao. 1975. Ordovician trilobite faunas of central and southwestern China. Palaeontologica Sinica, New Series B, 11: 1–463. (in Chinese and English) [Google Scholar].     

A new Late Ordovician microdomatid gastropod genus from Seville,south west Spain,with a revision of Ordovician Microdomatoidea

A new microdomatid gastropod, Eopagodea sevillana gen. and sp. nov., is described from the Late Ordovician (pre-Hirnantian Ashgill) limestones of Seville, Ossa Morena Zone, Spain. Palaeozoic microdomatids lived in shallow-water environments and were restricted to warm-water regions. Occurrence of microdomatid gastropods in the pre-Hirnantian Ashgill limestones of the Cerrón del Hornillo syncline (Ossa Morena Zone, Spain) is interpreted as an example of an influx of warm-water faunal elements into the otherwise cool to cold climate of the Mediterranean region during a short-termed, pre-Hirnantian increase of palaeotemperatures. The Late Ordovician microdomatid genus Daidia Wilson, 1951, is revised and two new Late Ordovician (Ashgill) subspecies of Daidia cerithioides (Salter, 1859) are described: Daidia cerithioides sewardensis n. subsp. from the Don River area of the York Mountains, Seward Peninsula, western Alaska, and Daidia cerithioides wilsonae n. subsp. from the Little East Lake Formation of northwestern Maine.     

Middle Ordovician (early Dapingian) conodonts in the Central Andean Basin of NW Argentina

Carlorosi, J., Heredia, S. & Aceñolaza, G, 2013. Middle Ordovician (early Dapingian) conodonts in the Central Andean Basin of NW Argentina. Alcheringa 37, 1–13. ISSN 0311-5518.

This paper describes and analyzes the significance of a conodont fauna from the Alto del Cóndor Formation, exposed in the Los Colorados region of the Argentine Eastern Cordillera. Identified taxa are Baltoniodus triangularis, Baltoniodus sp. cf. B. triangularis, Drepanodus sp., Drepanoistodus basiovalis, Drepanoistodus sp. B., Erraticodon patu, Gothodus costulatus, Oistodus sp., Trapezognathus diprion, T. quadrangulum, Triangulodus sp. and Triangulodus? sp. The presence of Baltoniodus triangularis indicates the base of the Dapingian stage (Middle Ordovician). In addition, we report the coexistence of T. diprion and T. quadrangulum. The conodont association suggests a faunal affinity with Baltica and South China, both belonging to the Shallow-Sea Realm of the Temperate-Cold Domain.

Josefina Carlorosi [josefinacarlorosi77@gmail]com], INSUGEO—Universidad Nacional de Tucumán—CONICET, Miguel Lillo 205, (4000) Tucumán, Argentina; Guillermo F. Aceñolaza [acecha@webmail.unt.edu.ar], Universidad Nacional de Tucumán—CONICET, Miguel Lillo 205, (4000) Tucumán, Argentina; Susana Heredia [sheredia@unsj.edu.ar], CONICET–CIGEOBIO and Instituto de Investigaciones Mineras, Facultad de Ingeniería, Universidad Nacional de San Juan, Urquiza y Libertador, (5400) San Juan, Argentina. Received 22.8.2012; revised 18.10.2012; accepted 24.10.12.     

Placocystella in the Early Devonian (Lochkovian) of central Victoria

Jell, P.A., 2013. Placocystella in the Early Devonian (Lochkovian) of central Victoria. Alcheringa, 567–569. ISSN 0311–5518.

The South African allanicytidiid mitrate carpoid Placocystella africana (Reed) is recorded for the first time from Australasia having been collected from a Lochkovian bed of the Humevale Formation at Mooroolbark in eastern Melbourne. The Southern Hemisphere Allanicytidiidae incorporating five monospecific genera in Brazil, South Africa, Tasmania, Victoria and New Zealand is now known to have a species in common between South Africa and Victoria. The previously suggested synonymy of these five is revised to accept Placocystella, Tasmanicytidium, Allanicytidium and Australocystis (but not Notocarpos) as synonymous so that the family contains Placocystella with four species and monospecific Notocarpos.

Peter A. Jell [p.jell@uq.edu.au], School of Earth Sciences, The University of Queensland, St Lucia Queensland 4072, Australia. Received 10.4.2013; revised 6.6.2013; accepted 17.6.2013.     

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.     

Early Silurian (Llandovery) trilobites from the Cotton Formation,near Forbes,New South Wales,Australia

A trilobite fauna from the upper part of the Cotton Formation (late Llandovery, Spirograptus turriculatus Zone) in central west New South Wales includes the new species Raphiophorus sandfordi, Odontopleura (Sinespinaspis) markhami and Aulacopleura pogsoni. Species of Odontopleura and Aulacopleura have not previously been documented in Australasia. The association of these genera is observed in offshore biofacies in the Llandovery/Wenlock on several palaeocontinents. Affinities of the species are with congeners from Bohemia and northwestern Canada (Odontopleura, Aulacopleura) and Tarim and South China (Aulacopleura, Raphiophorus).     

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.     

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.     

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.     

Biostratigraphic potential of Middle Cambrian hyoliths from the eastern Georgina Basin

Fourteen hyolith taxa are documented from the Middle Cambrian (Templetonian to Floran) of the eastern (Queensland) portion of the Georgina Basin, Australia, as a contribution toward a prospective Australian Cambrian hyolith biozonation. The described fauna is from the Beetle Creek Formation (including Monastery Creek Phosphorite Member) and Gowers Formation. Additionally, the enigmatic Cupittheca and some indeterminate hyoliths are figured to illustrate aspects of hyolith morphology. Guduguwan hardmani, widespread in Ordian-early Templetonian strata of northern Australia, is here recorded from the early Templetonian of the eastern Georgina Basin. A new family Gakidae is established for sulcavitide hyolithomorphs with a conch of pentagonally tabernacular transverse section, to include Gaka, Kalkatungu gen. nov. and possibly Dorsolinevitus. New genera are the hyolithid Yalarrnga mara gen. et sp. nov., sulcavitid Kulangarra kutjurru gen. et sp. nov., gakid Kalkatungu murlu gen. et sp. nov. and angusticornid Yuku tjurtu gen. et sp. nov.; new species are Loculitheca kunka sp. nov., Carinolithes tjikilirri sp. nov., ?Sololites kankari sp. nov., ?Shandongolithes thakal sp. nov., ?Gerkella thuka sp. nov. and ?Yacutolituus rakatju sp. nov. Taxa in open nomenclature are Foersteotheca cf. dubecensis, ?Holmitheca sp. and ?Dorsojugatus sp. On present knowledge, the potential for an Australian Cambrian hyolith biozonation is limited in the Early Cambrian, but for the Middle Cambrian, G. hardmani is a widespread Ordian-early Templetonian indicator, while hyolith distribution in the Monastery Creek Phosphorite Member suggests a faunal turnover at or about the incoming of Acidusus atavus which may provide a basis for biozonation in the Floran stage.