Fauna and biostratigraphy of the Cambrian (Series 2, Stage 4; Ordian) Tempe Formation (Pertaoorrta Group), Amadeus Basin,Northern Territory

A new faunal assemblage is reported from the Tempe Formation (Cambrian Series 2, Stage 4; Ordian) retrieved from the Hermannsburg 41 drillcore, Amadeus Basin, central Australia. Two trilobite taxa, including one new species Gunnia fava sp. nov., four brachiopod taxa, including the age-diagnostic Karathele napuru (Kruse), Kostjubella djagoran (Kruse) and Micromitra nerranubawu Kruse, together with a bradoriid, helcionellids, hyoliths, echinoderms, chancelloriids, sponges and problematic tubes are described. The fauna has close links to those of the neighbouring Daly, Georgina and Wiso basins and suggests that the Tempe Formation correlates with the Australian Ordian stage (either the Redlichia forresti or Xystridura negrina assemblage zones). The Giles Creek Dolostone in the eastern Amadeus Basin, previously regarded as coeval with the Tempe Formation, has recently been reported to be of early Templetonian age in its type section. The described taxa from the Tempe Formation confirm that these two sedimentary units are not contemporaneous and that regional stratigraphic schemes should be amended.     

Ecydsial efficiency and evolutionary efficacy among marine arthropods: implications for trilobite survivorship

A comparison of ecdysial patterns between trilobites and other macrobenthic marine arthropods (crabs, shrimp, lobsters, horseshoe crabs) reveals differences that may have evolutionary consequences. Limulus and many malacostracans apparently have a signature ecdysial style; conversely, a range of moult configurations characterized trilobite ecdysis, and this variation is evident even within individual species. A canalised ecdysial habit may be safer or metabolically more efficient and therefore, summed over the history of the class, evolutionarily advantageous. Some trilobite clades show evolutionary trends toward morphologies that would have facilitated ecdysis (e.g. reduction in the number of thoracic segments, reduction in the number and prominence of spines), but co-adaptation or multiple-use effects complicate the evolutionary signal of ecdysial selection. Survivorship analysis supports a possible link between ecdysial habit and evolutionary success: genera with fewer thoracic segments (= easier ecydsis) are longer-lived. The increased predation pressure on trilobites through the Palaeozoic would have amplified the evolutionary impact of an inefficient moult habit. The cumulative effects of a less-than-optimal ecdysial habit, and a physiology that apparently required reconstituting a calcitic exoskeleton de novo with each moult, are compelling biotic factors to consider in examining functional interpretations, life histories, evolutionary trends, and ultimate disposition of the Trilobita.     

Trilobite faunas and palaeoenvironmental setting of the Silurian (early Ludlow) Melbourne Formation,central Victoria

Trilobites are common faunal elements in the Melbourne Formation, a unit of early Ludlow (upper nilssoni Biozone) age, which crops out extensively in the Darraweit Guim Province of the Melbourne Zone, central Victoria. New diagnoses are given for species previously described, including Maurotarion euryceps (McCoy, 1876; = Cyphaspis spryi Gregory, 1901), Raphiophorus jikaensis (Chapman, 1912; = Ampyx yarraensis Chapman, 1912), Cromus simpliciculus (Talent, 1964), Cromus spryi (Chapman, 1912), Sthenarocalymene kilmorensis (Gill, 1945; = Gravicalymene hetera Gill, 1945) and Trimerus harrisoni (McCoy, 1876). A new phacopid genus, Orygmatos is described, represented by the species O. yanyeani gen. et sp. nov. Other species newly described include Cromus melbournensis sp. nov., Arcticalymene australis sp. nov., “Ananaspis” woiwurrungi sp. nov. and Kettneraspis hollowayi sp. nov.

Species composition of the trilobite fauna varies spatially, and a number of distinct assemblages can be defined. Abundant trilobite moult configurations are conclusive for interpretation of the benthic fauna as autochthonous, inferring depth estimations based on benthic community distribution to be valid. A depth-related succession of communities is recognised and indicate the Melbourne Formation was deposited at relatively shallow depths on a broad, eastwardly deepening shelf, with deposition dominated by storm processes. The palaeoenvironment comprised a BA-1 community including the Arcticalymene australis trilobite assemblage, restricted to very shallow depths (～20 m) on the SW coastal margin of the shelf and preserved in proximal tempestite lithologies; and a BA-5 community group containing three distinct trilobite assemblages dominated by species of Cromus and a deeper water fauna, preserved in distal tempestite lithologies and ranging widely over the shelf at depths in the range of maximum storm wave base (～50 – 80 m).     

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.     

The Late Cambrian trilobite Hamashania from Korea

The Late Cambrian trilobite genus Hamashania Kobayashi, 1942a has hitherto been poorly understood and is herein revised based on well-preserved specimens from Korea. Platysaukia Kobayashi, 1960 and Goumenzia Guo & Duan, 1978 are treated as junior synonyms of Hamashania. Hamashania comprises only two species, H. pulchera Kobayashi, 1942a and Pterocephalus busiris Walcott, 1905, and is restricted to North Chinaand Korea. The new genus Pacootasaukia is proposed to accommodate the Australian species Platysaukia jokliki Shergold, 1991 as type species, and Platysaukia tomichi Shergold, 1991, which are so distinct that they cannot be included within Hamashania. The generic concept of Mareda Kobayashi, 1942b, which was often confused with Hamashania, is confined to the type material.     

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.     

Healed injuries in Early Cambrian trilobites from South Australia

Examples of an undescribed species of the trilobite Redlichia from the Emu Bay Shale (Early Cambrian), Kangaroo Island, South Australia, show damage to the exoskeleton attributed to the action of predators. Injury was probably not lethal. The identity of the predators is unresolved, notwithstanding soft-part preservation within the fossil assemblage. Possible culprits include either a rare and presumably large animal such as an arthropod or conceivably cannibalism by Redlichia itself. This report provides new data on the occurrence of Cambrian predators, and casts further doubt on earlier suggestions that macrophagous predation was insignificant at this time. Aspects of trilobite predation during the Palaeozoic are reviewed, with emphasis placed on their ability to withstand substantial injuries and the possible repair mechanisms that promoted wound healing and survival.     

Late Middle Cambrian trilobites from St Valentines Peak and Native Track Tier,northwestern Tasmania

Late Middle Cambrian trilobites are described from two localities in northwestern Tasmania. Twenty-four trilobite taxa are documented. The 15 agnostoid species include Paraclavagnostus longus sp. nov. which is placed in the Utagnostinae, a new subfamily of the Clavagnostidae. The nine polymeroid species include a new member of the Rhyssometopidae, Tasmana truncata gen. et sp. nov. Three other new species of polymeroids are erected: Fuchouia tasmaniensis, Nepea delicata and Nepea hellyeri. Both faunas correlate with the Lejopyge laevigata Zone on the northern Australia biostratigraphic scale, possibly with the L. laevigata II Zone. When compared with Hunan, China, correlation is with the upper part of the Lejopyge laevigata Zone, and particularly with the lower part of the Proagnostus bulbus Zone.     

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].     

Upper Ordovician Phacopida (Trilobita) from Tasmania

Eastonian trilobite faunas of the Gordon Group in Tasmania include the new species Ceraurinella oepiki, Erratencrinurus trippi, and Pliomerina trisulcata, as well as a reedocalymeninid probably allied to Sarrabesia Hammann & Leone, 1997. Ceraurinella and Erratencrinurus have not previously been reported from Australia, the former being predominantly Laurentian but also known from NE China, the Himalaya, and Vietnam, and the latter mostly Baltic/Laurentian. Peri-Gondwanan species of Ceraurinella appear to form a clade, within which Tasmanian and Indian (central Himalayan) taxa are closest relatives.     

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 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.     

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.     

Shackleton Limestone archaeocyaths

A new monotypic genus of cheirurine trilobite, Azyptyx, is described based on the new species A. toongabbiensis from Early Devonian (late Lochkovian) limestones of the Wurutwun Formation near Toongabbie, Victoria. A feature of the genus that is unusual for the subfamily is a continuous basal glabellar furrow (S1) that does not normally meet the occipital furrow medially.     

A new trilobite species from the upper Rhuddanian (lower Silurian) of South China,and its biogeographical implications

Anacaenaspis yanpingensis sp. nov., from the lower Niuchang Formation (upper Rhuddanian, lower Llandovery, lower Silurian), is the first record of this genus from South China. The biogeographical distribution of Anacaenaspis and some other trilobite genera from South China (e.g., Gaotania, Hyrokybe, Aulacopleura and Raphiophorus) in the Llandovery evidences faunal exchanges between Avalonia–Baltica, Laurentia, Australia and South China. We attribute these dispersals to prevailing ocean currents, and especially equatorial countercurrents, which would have propagated dispersals during the Rhuddanian, shortly after the end-Ordovician mass extinction.     

First record of Procariama simplex Rovereto, 1914 (Phorusrhacidae,Psilopterinae) in the Cerro Azul Formation (upper Miocene) of La Pampa Province; remarks on its anatomy,palaeogeography and chronological range

Vezzosi, R.I., June 2012. First record of Procariama simplex Rovereto, 1914 (Phorusrhacidae, Psilopterinae) in the Cerro Azul Formation (upper Miocene) of La Pampa Province; remarks on its anatomy, palaeogeography and chronological range. Alcheringa, 157–169. ISSN 0311-5518.

New records of Procariama simplex in central and northwestern Argentina are reported. The fossil material includes mandibular bones, cervical vertebrae and several elements of the fore and hindlimbs. After an exhaustive comparison of anatomical characters and morphometric analysis, the fossil specimens are assigned to the psilopterine Procariama simplex. The specimen from La Pampa Province represents the first record of a psilopterine in this central region of Argentina and derives from upper Miocene sediments of the Cerro Azul Formation. Lithological features and biostratigraphical data allow the host bed to be assigned to the Huayquerian faunal stage (late Miocene). The La Pampa record broadens the geographical distribution of Procariama simplex, which was previously restricted to northwestern Argentina.

Raúl Ignacio Vezzosi [vezzosiraul@gmail.com], Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción CICYTTP-CONICET, Materi y España s/n (3105), Diamante, Entre Ríos, Argentina. Received 1.4.2011, revised 28.5.2011, accepted 14.6.2011.     

Llanvirn-early Caradoc trilobite biofacies of western Hubei and Hunan,China

On the basis of representative collections made from seven measured sections in western Hubei and Hunan, four early Llanvirn and five late Llanvirn-early Caradoc trilobite biofacies are distinguished along a bathymetric gradient from shallow to deep outer shelf. The diversity and relative abundance of mesopelagic cyclopygids gradually increased southwards or seawards. According to the facies association exhibited in the region, the upper limit of living depth for different forms is inferred as follows: 1) more than 70 m (M. (Microparia)); 2) less than 100 m (M. (Quadratapyge), Pricyclopyge, Aspidaeglina); 3) at approximately 100 m (Cyclopyge); and 4) more than 100 m (Symphysops, Psilacella). Benthic forms were absent in the deep outer-shelf basin because of stagnant conditions. In shallower sites of the outer shelf, genera of nileids in the carbonate facies and raphiophorids in the clastic facies were relatively abundant, but some endemic forms, such as the asaphid Birmanites and remopleuridid Hexacopyge, became dominant during the late Llanvirn-early Caradoc. Rorringtoniids are mainly associated with deeper outer-shelf facies. Panderia is common in an early Llanvirn nileid fauna at Yichongqiao, Cili area, and may well indicate development of shelf carbonate buildups. A transgressive event is suggested by the sudden appearance of rich Cyclopyge in the early Caradoc at Jiuxi, Changde.     

New ontogenetic information on Duyunaspis duyunensis Zhang & Qian in Zhou et al., 1977 (Trilobita,Corynexochida) from the Cambrian and its possible sexual dimorphism

Lei, Q.P., September .2015. New ontogenetic information on Duyunaspis duyunensis Zhang & Qian in Zhou et al., 1977 (Trilobita, Corynexochida) from the Cambrian and its possible sexual dimorphism. Alcheringa 40, XXX–XXX. ISSN 0311-5518.

The hypostomal condition and the complete ontogenetic development of Duyunaspis duyunensis Zhang & Qian in Zhou et al., 1977 are restudied on the basis of abundant specimens from the Balang Formation (Cambrian, Qiandongian) in Zila Village, Paiwu Township, Huayuan County, Hunan Province. The relatively complete ontogenetic series (degree 0 to 9) provides new evidence that the holaspis of this species has nine rather than seven thoracic segments as proposed by McNamara et al. (2006). Comparisons between Duyunaspis duyunensis and two associated species, Arthricocephalus chauveaui and Changaspis elongata, support its placement in the Subfamily Oryctocarinae. Moreover, based on observations of a large number of specimens, the presence of an anterior indentation on the pygidial end is possibly representative of sexual dimorphism.

Qianping Lei [cicelyapple@126.com], Natural Department, Changzhou Museum, Changzhou, Jiangsu Province, 213022, PR China; State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, 210008, PR China.     

Editorial

Similarities in late Middle Cambrian trilobite, inarticulate brachiopod and molluscan faunas are apparent between Bornholm (Denmark) and New Zealand. Tuarangia gravgaerdensis sp. nov. is described from the late Middle Cambrian Andrarum Limestone of Bornholm, Denmark. The Andrarum Limestone is stratigraphically correlated with the Tasman Formation, New Zealand, from where the genus Tuarangia was first described. A single specimen, referred to Tuarangia, has been found in an erratic boulder from NW Poland. The boulder is estimated to be of early Late Cambrian age. The initial taxonomic assignment of Tuarangia to the Bivalvia, Subclass Pteriomorphia, is upheld. The distance between Bornholm and New Zealand, the position at opposite hemispheres, and the palaeogeography in general clearly indicate isocommunities with restricted possibility of exchange of the gene pool at species level.