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Heliolitine tabulate corals are extremely rare in pre-Katian (Upper Ordovician) rocks worldwide, hindering the understanding of their origin and early evolution. Here, we systematically study new heliolitine material from the upper member (Sandbian) of the Huadan Formation in the Yunnan-Sichuan border area, Southwest China, which includes Protaraea ningnanensis, Plasmoporella kiaeri, Wormsiporasp. and Heliolites spinosus. The findings indicate that Protaraeaand Heliolitesare ancestral forms of coccoserids and typical tubular heliolitines, respectively, and that the absence of trabecular septa is probably a primitive feature of plasmoporellids. The refined Ordovician stratigraphy of this area implies that the coccoserid Protaraea ningnanensisLin, 1965 from the lower member (late Darriwilian) of the Huadan Formation is the earliest known heliolitine, which further indicates that all heliolitines might have evolved from Protaraea. The comparison of Protaraeawith other early tabulate corals also suggests an independent heliolitine origin from auloporinids and sarcinulinids.

The conodont fauna from the Willara Formation, a carbonate-dominated stratigraphic unit widely distributed in the subsurface Canning Basin of Western Australia, is represented by 41 species, including a new species, Erraticodon neopatuZhen n. sp. The Jumudontus ganandaand Histiodella altifronsbiozones are recognized in the lower and upper parts, respectively, of the Willara Formation. Deposited primarily in shallow nearshore settings, the Willara Formation is characterized by the occurrence of predominantly long-range coniform species of Triangulodus, Scalpellodus, Drepanoistodus, Drepanodus, and Kirkupodus. Several widely distributed age-diagnostic species, including Histiodella altifrons, Histiodella holodentata, Histiodella serrata, and Jumudontus gananda, serve as keys for biostratigraphic analysis and correlation. Our study also shows that the basal and top boundaries of the Willara Formation are diachronous across the basin, extending from the middle Floian (Oepikodus communisBiozone) to middle Darriwilian (Histiodella holodentata-Eoplacognathus pseudoplanusBiozone). This contribution provides crucial new biostratigraphic data for precise correlation of the Willara Formation with its time equivalents regionally and internationally.

AbstractCorals representing the sole occurrence of C/S Fauna IV of the regional biostratigraphic scheme occur in limestone in the uppermost Malachis Hill Formation of the Bowan Park area, central New South Wales. New species described and illustrated from this fauna include the rugosan Bowanophyllum ramosumand tabulate Hemiagetiolites longiseptatus. Also documented are three other distinct species of Hemiagetiolites, H. spinimarginatus(Hall, 1975), H.sp. cf. H. palaeofavositoides(Lin & Chow, 1977) and H. sp., an unnamed species of Paleofavosites, and three heliolitine corals, Heliolites waicunensisLin & Chow, 1977, Navoites cargoensis(Hill, 1957) and Plasmoporellasp. These descriptions, which complete knowledge of the entire fauna collected over 50 years, enable interesting conclusions to be drawn regarding palaeogeographic affinities of this youngest in situOrdovician coral fauna known from eastern Australia. Its remarkable similarities to contemporaneous coral faunas from South Tien Shan and the Chu-Ili Terrane indicate strong connections between eastern Australia and the latter two terranes, supporting their positioning in equatorial latitudes of eastern peri-Gondwana. However, it is puzzling that fewer similarities exist between the eastern Australian coral fauna and those from rocks of Katian age in SE China, which may be due to either a slightly younger age of the former fauna or a relatively higher palaeolatitudinal position of South China.Guangxu Wang [gxwang@nigpas.ac.cn], State Key Laboratory of Palaeobiology and Stratigraphy; Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing Institute of Geology and Palaeontology, Nanjing 210008, China; Ian G. Percival [ian.percival@planning.nsw.gov.au], and Yong Yi Zhen [yong-yi.zhen@planning.nsw.gov.au], Geological Survey of New South Wales, 947–953 Londonderry Road, Londonderry, NSW 2753, Australia.

Zhen, Y.Y., Normore, L.S., Dent, L.M. & Percival, I.G., 11 July 2019. Middle Ordovician (Darriwilian) conodonts from the Goldwyer Formation of the Canning Basin, Western Australia. Alcheringa44, 25–55. ISSN 0311-5518Middle Ordovician conodonts attributed to 46 species were recovered from a stratigraphic interval spanning the Willara, Goldwyer and Nita formations in core sections from the Sally May-2 and Theia-1 petroleum exploration wells in the Canning Basin, Western Australia. The Histiodella serrata, Histiodella holodentataand Eoplacognathus pseudoplanusbiozones are recognized in the lower and middle part of the Goldwyer Formation, indicative of an early–middle Darriwilian age. This revised conodont biostratigraphy enables more precise correlation with North America and North and South China. Several biogeographically distinctive conodont species, most likely of North Chinese origin, are recorded from the Goldwyer Formation. Their presence signals a strong palaeobiogeographic connection between the Sino-Korean Craton and the Canning Basin on the western margin of eastern Gondwana during the late Middle Ordovician.Y.Y. Zhen* [yong-yi.zhen@planning.nsw.gov.au], W.B. Clarke Geoscience Centre, Geological Survey of New South Wales, 947–953 Londonderry Road, Londonderry NSW 2753, Australia; L.S. Normore [leon.normore@dmirs.wa.gov.au]; L.M. Dent [louisa.dent@dmirs.wa.gov.au], Department of Mines, Industry Regulation and Safety, Mineral House, Geological Survey of Western Australia, 100 Plain Street, East Perth, WA 6004, Australia; I.G. Percival [ian.percival@planning.nsw.gov.au], W.B. Clarke Geoscience Centre, Geological Survey of New South Wales, 947–953 Londonderry Road, Londonderry NSW 2753, Australia;

Conodonts and microbrachiopods of latest Cambrian–earliest Ordovician age are documented from the Handler Formation of northern Victoria Land, Antarctica. Five spot samples from allochthonous limestone clasts collected during expeditions conducted by the Korean Polar Research Institute in 2013–2014 yielded the conodonts Cordylodus proavus, C. lindstromi, Hirsutodontus simplex, and Teridontus nakamurai, associated with four species of brachiopods (two indeterminate acrotretides, a zhanatellid lingulide, and a siphonotretide tentatively referred to Schizambon reticulatus). The four conodont species are distinctive taxa occurring in the widely distributed Cordylodus lindstromiBiozone of the latest Cambrian and the IapetognathusBiozone at the base of the Ordovician. The allochthonous limestone clasts in the Handler Formation were likely derived from now-lost carbonate shelves developed locally (in the Bowers Arc) or transported from further north. Fossil evidence from the Handler Formation indicates that the final episode of the Ross Orogeny that uplifted and deformed the Robertson Bay Group was no older than early Tremadocian (earliest Ordovician). Striking similarities in fossil content, ages and depositional settings between the limestone olistoliths in the Handler Formation and latest Cambrian–earliest Ordovician autochthonous and allochthonous carbonates of the post-Delamerian Orogen recognized in the Koonenberry Belt (Gnalta Shelf) in far western New South Wales support the depositional model considering the Robertson Bay Group as the synorogenic deposits of the Ross Orogeny.

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 compressaand Phragmodus undatus–Tasmanognathus careyibiozones are successively represented in the Sandbian. Although the Erismodus quadridactylusBiozone 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 insculptusand Aphelognathus grandisbiozones, are established in the Katian of eastern Australia. Taoqupognathusspecies 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, Tasmanognathusand 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.

Zhen, Y.Y., Wang, G.X. & Percival, I.G.,August 2016. Conodonts and tabulate corals from the Upper Ordovician Angullong Formation of central New South Wales, Australia. Alcheringa 41, xxx–xxx. ISSN 0311-5518.The Angullong Formation is the youngest Ordovician unit exposed in the Cliefden Caves area of central New South Wales. Its maximum age is constrained by a Styracograptus uncinatusgraptolite Biozone fauna at the very top of the underlying Malongulli Formation, but the few fossils previously reported from higher in the Angullong Formation are either long-ranging or poorly known. From allochthonous limestone clasts in the middle part of the formation, we document a conodont fauna comprising Aphelognathus grandis, A. solidum, Aphelognathussp., Aphelognathus? sp., Belodina confluens, Drepanoistodus suberectus, Panderodus gracilis, Panderodussp., Phragmodus undatus, Pseudobelodina inclinataand Pseudobelodina? sp. aff. P. obtusa, which supports correlation with the Aphelognathus grandisBiozone (late Katian) of the North American Midcontinent succession. The species concepts of Aphelognathusand Pseudobelodinaare reviewed in detail. Associated corals are exclusively tabulates, dominated by agetolitids, including Agetolites angullongensissp. nov., Heliolites orientalis, Hemiagetolites breviseptatus, Hemiagetolitessp. cf. H. spinimarginatus, Navoitessp. cf. N. circumflexa, Plasmoporella bacilliforma, P. marginata, Queporasp. cf. Q. calamusand Sarcinulasp. Affinities of the coral fauna from the Angullong Formation are closer to faunas from northern NSW and northern Queensland than to the locally recognized Fauna III of late Eastonian age in central NSW. We propose a subdivision of Fauna III to account for this difference, with the late Katian Fauna IIIB characterized by the incoming of agetolitid corals. The currently known distribution of representatives of this group with adequate age constraints suggests that agetolitids possibly originated in North China, subsequently migrating to Tarim, South China and adjacent peri-Gondwanan terranes while also spreading eastward to northern Gondwana, where they progressively moved through eastern Australia to reach the central NSW region by the early Bolindian.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; Guangxu Wang (gxwang@nigpas.ac.cn), State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, 39 East Beijing Road Nanjing 210008 PR China.

Wang, G., Percival, I.G. & Li, R., 25.2.2015. Remarks on the pattern of septal insertion in rugose corals. Alcheringa 39, xxx–xxx. ISSN 0311-5518Well-preserved specimens of the Hirnantian (latest Ordovician) rugose coral Lambeophyllum? corniculumHe from the Yangtze Platform of South China, clearly show how catasepta (minor septa) are inserted, confirming the model proposed by Weyer in the 1970s. Our observations indicate the insertion of counter lateral septa and their neighbouring catasepta on the counter side takes place in exactly the same manner as that of the subsequent metasepta and catasepta. We propose abandoning the use of the term counter lateral septa. Therefore, exclusion of the pair of counter lateral septa reduces the number of protosepta from six to four.Guangxu Wang [gxwang@nigpas.ac.cn], State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (CAS), 39 East Beijing Road, Nanjing 210008, PR China; Ian G. Percival [ian.percival@trade.nsw.gov.au], Geological Survey of New South Wales, 947–953 Londonderry Road, Londonderry, NSW 2753, Australia; Rongyu Li [lir@brandonu.ca], Department of Geology, Brandon University, Manitoba R7A 6A9, Canada.

The Australasian Superprovince, a biogeographical entity defined by shallow water conodont faunas that mainly inhabited Ordovician tropical zones of eastern Gondwana and peri-Gondwanan continental blocks and terranes, is characterized by the occurrence of serratognathids in the Floian. Biostratigraphic correlation of the Floian Stage within the Australasian Superprovince is based primarily on species of Serratognathus, Prioniodusand Oepikodus, which are distributed across South China, North China, the Tarim Basin, Korea, Indochina, Sibumasu, Kazakhstan and Australia. Conodont biozones from the shallow water Yangtze Platform succession of South China, from oldest to youngest the Serratognathus diversus, Prioniodus honghuayuanensis, Oepikodus communis, and O. evaebiozones, correlate respectively with the Serratognathus bilobatus, Prioniodus elegans, and O. evaebiozones recognized in the succession of the deeper-water Jiangnan Slope. Paroistodus proteus, a zonal index species of late Tremadocian to earliest Floian age in Baltoscandia, occurs abundantly in the slope setting of South China and in outer-shelf settings in Western Australia. Other zonal index species of the Baltoscandian middle and late Floian succession that are recognized in South China include P. elegans(only reported from the Jiangnan Slope) and O. evae, which is widespread on the slope and deeper parts of the Yangtze Platform. O. evaeis, however, confined to deep water basin successions in Australia. O. communis(zonal index species for the middle Floian of the Ibexian Series in the North American Midcontinent fauna) is common in the middle-upper Floian Stage in Australia, but is relatively rare in South China.

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 lindstromiBiozone, Cordylodus angulatusBiozone, Chosonodina herfurthiBiozone, Paltodus deltiferBiozone, Paroistodus proteusBiozone, Triangulodus bifidusBiozone, Serratognathus diversusBiozone and Prioniodus elegansBiozone. Several zonal index species of the Baltoscandian succession—Paltodus deltifer, Paroistodus proteusand Prioniodus elegans—are described and illustrated in detail for the first time from South China. Co-occurrence of P. proteusand Serratognathus bilobatusin several samples below the appearance of P. elegansalso confirms correlation of the S. diversusBiozone (basal Floian) with the upper P. proteusZone 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.

The biogeographical patterns shown by Ordovician linguliform and craniiform brachiopods are greatly influenced by their dominance in low-diversity associations in marginal environments. This is particularly evident in the Early Ordovician, when linguliform-dominated dysaerobic assemblages are widely distributed along the deep shelves of Gondwana, the Kazakhstanian terranes and in Baltica. By the Darriwilian, micromorphic linguliforms are characteristic components of the pantropical climatic-controlled faunas of Laurentia, Cuyania and Kazakhstanian terranes, which – in spite of separation by extensive oceans – retain a distinct similarity. Analysis of craniiform biogeographical distribution is impeded significantly by the poor state of craniide taxonomy and lack of reliable data from most regions. However, in general their biogeographical dispersion is similar to other groups of the Palaeozoic Evolutionary Fauna. Unlike the linguliforms, which are important members of the Cambrian Evolutionary Fauna, there is no convincing Cambrian craniiform record; they may have evolved and dispersed from Gondwana and associated microcontinents and island arcs. The earliest well-established record is from the late Tremadocian of temperate to high-latitude peri-Gondwana. During most of the Ordovician, they have a peri-Iapetus distribution. They are very rare or absent in tropical Gondwana, South China and Kazakhstanian terranes and are not yet documented from Siberia. The trimerellides probably evolved in tropical peri-Gondwanan island arc settings. Their dispersion and major features of biogeography mirror those of atrypides.

The phylogeographical evolution and the consequent changing distribution and diversity of rhynchonelliform brachiopods through the Ordovician are linked to the dynamic palaeogeography of the period. The Early Ordovician (Tremadocian and Floian) is characterized by globally low-diversity faunas with local biodiversity epicentres, notably on the South China Palaeoplate; low-latitude porambonitoid-dominated faunas with early plectambonitoid and clitambonitoid representatives, as well as high-latitude assemblages mostly dominated by orthoids, can be recognized, but many taxa are rooted in Late Cambrian stocks. The Early Ordovician displays a steady increase in rhynchonelliformean biodiversity, which was mostly driven by the increasing success of the Porambonitoidea and Orthoidea, but the billingsellids and early plectambonitoids also contributed to this expansion. During the Early to Mid Ordovician (Dapingian–Darriwilian), marine life experienced an unprecedented hike in diversity at the species, genus and family levels that firmly installed the suspension-feeding benthos as the main component of the Palaeozoic fauna. However, this may have occurred in response to an early Darriwilian annihilation of existing clades, some of which had been most successful during the Early Ordovician. New clades rapidly expanded. The continents were widely dispersed together with a large number of microcontinents and volcanic arcs related to intense magmatic and tectonic activity. Climates were warm and sea-levels were high. Pivotal to the entire diversification is the role of gamma (inter-provincial) diversity and by implication the spread of the continents and frequency of island arcs and microcontinents. The phylogeographical analysis demonstrates that this new palaeogeographical configuration was particularly well explored and utilized by the strophomenides, especially the Plectambonitoidea, which radiated rapidly during this interval. The porambonitoids, on the other hand, were still in recovery following the early Darriwilian extinctions. Orthides remained dominant, particularly at high latitudes. Biodiversity epicentres were located on most of the larger palaeoplates, as well as within the Iapetus Ocean. Provincial patterns were disrupted during the Sandbian and early Katian with the migration of many elements of the benthos into deeper-water regimes, enjoying a more cosmopolitan distribution. Later Katian faunas exhibit a partition between carbonate and clastic environments. During the latest Katian, biogeographical patterns were disrupted by polewards migrations of warm-water taxa in response to the changing climate; possibly as a consequence of low-latitude cradles being developed in, for instance, carbonate reef settings. Many clades were well established with especially the strophomenides beginning to outnumber the previously successful orthides, although this process had already begun, regionally, in the mid to late Darriwilian. At the same time, atrypoid and pentameroid clades also began to radiate in low-latitude faunas, anticipating their dominance in Silurian faunas. The Hirnantian was marked by severe extinctions particularly across orthide-strophomenide clades within the context of few, but well-defined, climatically controlled provincial belts.Supplementary material:The individual localities and a reference list for the data sources are provided at: http://www.geolsoc.org.uk/SUP18667

The biogeographical distribution of Ordovician and Silurian gastropods, monoplacophorans and mimospirids has been analysed on a generic level. The dataset contains 334 genera and 2769 species, yielding 1231 records of genera with 2274 occurrences worldwide. There is a bias towards eastern Laurentia, Baltica and Perunica records. Some 53.1% of the records are Ordovician. The study demonstrates that these molluscs are well suited to being used to improve understanding of Ordovician and Silurian biogeographical provinciality. Specific points are that: a Lower Ordovician assemblage is evident in Laurentia; the fauna of the Argentinean Precordillera is Laurentian until the Darriwilian, when taxa are shared with North China; Late Silurian gastropods from the Alexander terrane (SE Alaska) are unknown in Laurentia, but support a rift origin of this terrane from NE Siberia; Perunica, Ibero-Armorica and Morocco cluster together throughout the Ordovician but Perunica and Morocco are closer; Darriwilian–Sandbian deep-water Bohemian taxa occur in Baltica; a Laurentian–Baltica proximity is unsupported until the Silurian; Siberia clusters with North China and eastern Laurentia during the Tremadocian–Darriwilian; during the Gorstian–Pridoli Siberia clusters with the Farewell and Alexander terranes; North China may have been close to Laurentia and the Argentinean margin of Gondwana; and the affinity of Tarim taxa is problematic.