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1.
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.  相似文献   

2.
Three forms of exuviation, involving inversion of exoskeletal elements, are described in three Australian species of the Cambrian trilobite Redlichia: R. forresti (Foord), R. idonea Whitehouse and R. micrograpta Öpik. They are: inversion of the pygidium, in four specimens of R. forresti; inversion of some thoracic segments of R. idonea; and lateral inversion of a free cheek, in single specimens of R. forresti and R. micrograpta. This is the first record of thoracic segment inversion during exuviation in trilobites. Exuviae with inverted exoskeletal elements provide information on the techniques of exuviation, in particular the direction of egression of the postecdysial trilobite from the proecdysial exuvia and also in this genus, the extent of enrolment of the thorax.  相似文献   

3.
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.  相似文献   

4.
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.  相似文献   

5.
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.  相似文献   

6.
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.  相似文献   

7.
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.  相似文献   

8.
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).  相似文献   

9.
10.
Jell, P.A., 2014. A Tremadocian asterozoan from Tasmania and a late Llandovery edrioasteroid from Victoria. Alcheringa 38, 528–540. ISSN 0311-5518.

An asterozoan, Maydena roadsidensis gen. et sp. nov., is described from the mid-Tremadocian (La1b Zone) Florentine Valley Formation in southwestern Tasmania and is the oldest known asterozoan in the world. Although only a single, largely dissociated, specimen is available, enough is preserved to recognize distinctive ambulacral plates similar to those of Archegonaster Jaekel from the Llanvirn of the Czech Republic. Reciprocodiscus transambus n. gen., n. sp. is an isorophid edrioasteroid from the uppermost late Llandovery Springfield Formation exposed in the bed of Deep Creek, near Springfield, 65?km north northwest of Melbourne. It occurs with a low-diversity trilobite fauna indicating a deepwater, subphotic environment. This edrioasteroid has in each ambulacrum a single series of floor plates that are not visible on the oral surface, indicating its isorophid affinity and retains certain apparently primitive features that are not seen in post-Cambrian edrioasteroids, such as the very large plates of the marginal circlet, plated aboral surface and ambulacral tips extending onto the marginal circlet plates.

Peter A. Jell [] School of Earth Sciences, The University of Queensland, St Lucia Queensland 4072, Australia.  相似文献   

11.
The Cambrian acrotretid brachiopod Neotreta Sobolev 1976 is reviewed and re-illustrated, based on new material of the type species, N. tumida Sobolev 1976, from the lower Upper Cambrian of Siberia; Neotreta orbiculata Koneva 1990, originally described from the Middle Cambrian of Kazakhstan, has been obtained from roughly coeval beds in Shropshire, England; Neotreta pusilla Koneva 1986 was unavailable for study. Two new species, N. davidi and N. karagailensis, are described from Queensland, Australia, and Kirgizia, Central Asia respectively.  相似文献   

12.
There is little osteological evidence of non‐lethal predation events in the archaeological or vertebrate paleontological record. A small section of Pliocene cetacean rib collected from the Yorktown Formation within the PCS Phosphate Mine (formerly Lee Creek Mine), Aurora, North Carolina, U.S.A., shows evidence of this kind of trophic interaction. In this case study, we offer a diagnosis of bone traumatic pathology in which three bone‐forming lesions on the partial rib are interpreted as the reaction to a bite inflicted by a macro‐predator, the first such report from a marine environment. In addition to the three well‐defined lesions, a thin layer of woven bone covers much of the remaining cortical bone. The combination of the three bone‐forming lesions and the thin layer of woven bone suggest the presence of an inflammatory process almost certainly caused by infection secondary to the trauma. Survival following the traumatic event was probably less than 6 weeks. The Neogene chondrichthyan fauna from this locality preserves several large predators, including Carcharocles megalodon, Carcharodon carcharias, Isurus xiphidon and Parotodus benedeni, which were all capable, at least in terms of their size, of having bitten the cetacean. Although most of the odontocetes known from the Yorktown Formation were too small to have inflicted this wound, some of the physeterids may have been large enough to have caused the lesions on the partial rib. This evidence of predation in Pliocene whale bone raises the possibility of similar lesions being found in whale bone recovered from archaeological sites. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
Animal fear can be an important driver of ecological community structure: predators affect prey not only through predation, but also by inducing changes in behaviour and distribution—a phenomenon evocatively called the “ecology of fear.” The return of wolves to the western United States is a notable instance of such dynamics, yet plays out in a complex socioecological system where efforts to mitigate impacts on livestock rely on manipulating wolves' fear of people. Examining Washington state's efforts to affect wolf behaviour to reduce livestock predation, we argue that this approach to coexistence with wolves is predicated on relations of fear: people, livestock, and wolves can arguably share landscapes with minimal conflict, as long as wolves are adequately afraid. We introduce the “socioecology of fear” as an interdisciplinary framework for examining the interwoven social and ecological processes of human-wildlife conflict management. Beyond frequently voiced ideas about wolves' “innate” fear, we examine how fear is (re)produced through human-wolf interactions and deeply shaped by human social processes. We contribute to the critical physical geography project by integrating critical social analysis with ecological theory, conducted through collaborative interdisciplinary dialogue. Such integrative practice is essential for understanding the complex challenges of managing wildlife in the Anthropocene.  相似文献   

16.
Peel, J.S., February 2017. First records from Laurentia of some middle Cambrian (Series 3) sponge spicules. Alcheringa 41, 000–000. ISSN 0311-5518.

Spicules of the sponges Silicunculus Bengtson, Australispongia Dong & Knoll and Thoracospongia Mehl are described from the middle Cambrian (Cambrian Series 3) of North Greenland. The occurrences document the first records from the Cambrian of Laurentia of spicules initially reported from Australia. Obese spicules of Thoracospongia are now known to occur in strata of Cambrian Series 2 (Stage 4, Botoman) to Cambrian Series 3 (Stage 5 and Drumian) age in Australia, northern and southeastern Siberia and in the uppermost Henson Gletscher Formation (Cambrian Series 3, Stage 5) of western Peary Land. Morphologically similar obese spicules from the USA, Jordan, Iran and Sweden suggest an evolutionary trend towards armouring of the outer sponge surface during the middle and late Cambrian. New species described are Silicunculus saaqqutit sp. nov., Thoracospongia lacrimiformis sp. nov.

John S. Peel [], Department of Earth Sciences (Palaeobiology), Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden. Received 3.7.2016; revised 13.9.2016; accepted 15.9.2016.  相似文献   


17.
Regional biofacies analysis has been neglected in biostratigraphic studies of the Cambrian-Ordovician boundary interval. Cluster analysis of relative abundance data of trilobites in thirty-seven large collections from ten localities in North America outlines eleven biofacies in the mid-Trempealeauan to early Tremadocian interval. The biofacies are largely lithofacies-specific and are differentiated at generic and familial levels. The composition of trilobite zonal associations in the boundary interval is controlled principally by the sequence of biofacies. Available trilobite zonal schemes can be used only within single lithofacies. The biofacies patterns and faunal dynamics across the upper boundary of the Ptychaspid Biomere do not support hypotheses requiring catastrophic events. In coherence and geographic distribution, Late Cambrian trilobite biofacies are similar to post-Cambrian benthic biofacies.  相似文献   

18.
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.  相似文献   

19.
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 and ], 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.  相似文献   

20.
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