Trilobite Taxa Research Articles

The Rare Trilobites Exallaspis (Odontopleuridae) and Kosovoproetus? (Tropidocoryphidae) in the Homerian (Silurian) Of The Prague Basin, Bohemian Massif

Abstract The deep-water Aulacopleura koninckii Assemblage in the lower Homerian (T. testis Sub-Biozone) “Aulacopleura shales“ strata at the classical ‘Barrande’s pits’ locality on the Černidla hillside at Loděnice in the Prague Basin is supplemented by the addition of two new trilobite taxa, viz. Exallaspis? perunicana sp. n. and Kosovoproetus? aff. praecursor (Přibyl & Vaněk 1987). The palaeogeographic distribution of Exallapis Ramsköld & Chatterton, 1991 is extended by the occurrence of Exallaspis? perunicana sp. n. and the younger Exallaspis sp. in the upper Homerian (the P. parvus – G. nassa Biozone) of the Prague Basin, reflecting the faunal migration between the southern shelf of the Baltica palaeocontinent and the Perunica microcontinent accross the Rheic Ocean. The small dimensions of the K.? aff. praecursor exoskeletons compared to those of K.? praecursor in the bordering shallow-water Liolalax–Sphaerexochus– Cheirurus Assemblage represent another example of adaptive nanism in trilobites of the Aulacopleura-Raphiophorus Biofacies.

New dalmanitid trilobite taxa from the Lower Devonian of Argentina: comments on spinosity in endemic taxa from southern high paleolatitudes

Three new Lower Devonian dalmanitid trilobite taxa are recognized from the Talacasto Formation in the Precordillera Basin, Argentina, which includes two monospecific genera (Ivanites leonorae n. gen., n. sp. and Aguaditaspis mediaspina n. gen., n. sp.), and one additional new genus and species left in open nomenclature. These taxa combine characters of the subfamilies Dalmanitinae Vogdes, 1890 and Synphoriinae Delo, 1935, challenging their taxonomic distinction. Forty percent of the dalmanitids from high paleolatitudinal basins from southwestern Gondwana (Malvinokaffric) exhibit non-homologous dorsal spinosity. Aguaditaspis mediaspina n. gen., n. sp. shares similar spines with Trypaulites calypso (Hall, 1861). The unnamed new genus resembles the spinosity of endemic Malvinokaffric dalmanitids, like Dalmanitoides Delo, 1935 and Fenestraspis Braniša & Vaněk, 1973. Considered defensive, the recorded spinosity along with putative sublethal-attack marks, suggest higher predation pressure than previously thought at high paleolatitudes. This evidence is in accordance with some hypothesis on rising predation pressure in the mid-Paleozoic marine ecosystems.

A Guzhangian (late Middle Cambrian) fauna from the Gidgealpa 1 drillhole, Warburton Basin, South Australia

A Cambrian Series 3 (Guzhangian, Boomerangian) fauna is described from Core 12 of the Gidgealpa 1 drillhole from the Warburton Basin, northeastern South Australia. There are four agnostoid taxa: Ammagnostus laiwuensis, Lejopyge calva, L. armata and an unassigned pygidium, and six polymerid trilobite taxa: Fuchouia sp., Dorypyge sp., Solenoparia changi sp. nov., Pianaspis sp., an unassigned cranidium and an unassigned pygidium. This fauna suggests a correlation with the Goniagnostus nathorsti Zone or the lower part of the Lejopyge laevigata Zone (Boomerangian on the northern Australian biostratigraphic scheme), with the latter preferred. These are the first published descriptions of fossils of this age from the Warburton Basin. Xiaowen Sun [Xiaowen_s@yahoo.com.au], Sun Petroleum Geoservices, 4 Jolie Grove, Box Hill, Victoria 3128, Australia; Christopher J. Bentley [ bigfossil@bigpond.com], 30 Albert Street, Clare, South Australia, 5453, Australia; James B. Jago [jim.jago@unisa.edu.au], University of South Australia–STEM, Mawson Lakes, South Australia 5095, Australia.

Trilobites from the mid-Darriwilian (Middle Ordovician) of the Amadeus Basin, central Australia

Sixteen species of trilobites are described from the Middle Ordovician (mid-Darriwilian, Da2) Stairway Sandstone and Stokes Siltstone at multiple spot localities from the Amadeus Basin, Northern Territory, central Australia. New trilobite taxa described include two new genera: Ghanaspis gen. nov. and Iridis gen. nov.; as well as five new species; Eisarkaspis jonesi sp. nov., Ghanaspis ritchiei gen. et sp. nov., Iridis schoonorum gen. et sp. nov., Lycophron titan sp. nov., and Norasaphus (Norasaphus) patersoni sp. nov. Of these, Lycophron titan sp. nov. is the largest species of trilobite so far documented from Australia and possibly the third largest in the world. Also redescribed is Basilicus thorntoni [=Asaphus (Megalaspis?) thorntoni] based on the recently rediscovered type material and additional specimens from elsewhere in the basin. *P.M. Smith [Patrick.Smith@austmus.gov.au], Palaeontology Department, Australian Museum Research Institute, Sydney, New South Wales, 2010, Australia and, Department of Biological Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia; J.R. Laurie [john.r.laurie@gmail.com], Department of Biological Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia.

Trilobites and agnostids from the Goyder Formation (Cambrian Series 3, Guzhangian; Mindyallan), Amadeus Basin, central Australia.

A new assemblage containing twenty-two species of trilobites and agnostids is described from the Goyder Formation (Cambrian Series 3) in the Ross River Syncline and Gardiner Ranges of the Amadeus Basin, Northern Territory, central Australia. New trilobite taxa described include the genus, Trephina gen. nov., and four new species Adelogonus prichardi sp. nov., Hebeia stewarti sp. nov., Liostracina joyceae sp. nov., and Trephina ranfordi sp. nov. Two agnostid taxa previously known only from Antarctica, Ammagnostus antarcticus Bentley, Jago Cooper, 2009 and Hadragnostus helixensis Jago Cooper, 2005, are also documented. Of the two agnostid species, the latter is the most age diagnostic, previously reported from the Cambrian Series 3 (Guzhangian; late Mindyallan; Glyptagnostus stolidotus Zone) Spurs Formation in Northern Victoria Land. This age for the Goyder Formation assemblage is supported by the co-occurrence of the trilobites Biaverta reineri Öpik, 1967, Blackwelderia repanda Öpik, 1967, Henadoparia integra Öpik, 1967, Monkaspis cf. travesi (Öpik, 1967), Nomadinis pristinus Öpik, 1967, Paraacidaspis? priscilla (Öpik, 1967), and Polycyrtaspis cf. flexuosa Öpik, 1967, also known from the late Mindyallan (G. stolidotus Zone) successions of the neighbouring Georgina Basin (Northern Territory and Queensland). The generic assemblage of the Goyder Formation is also similar to those from the Guzhangian (Mindyallan) of other parts of Australia (New South Wales, South Australia, and Western Australia), in addition to East Antarctica and North and South China.

Recent Geoethical Issues in Moroccan and Peruvian Paleontology

The cases of Joan Corbacho from Spain, and Klaus Honninger and Carlos A. Vildoso from Peru, considered by some as prestigious paleontologists in their countries, are discussed here. The first one is a fossil collector and trader that, without a minimal scientific knowledge, published ca. 20 papers with proposals for a dozen new trilobite taxa coming from different Paleozoic formations in the Moroccan Anti-Atlas. Descriptions of new taxa seem formally valid but are rather inadequate, often based on poorly preserved material of dubious geological provenance, and mostly published as papers without peer review in a local journal, managed by a private museum connected to the Seminary of Barcelona. Besides this, part of the published and figured trilobite specimens were later offered for sale in the internet, sometimes accompanied with a ‘certificate of authenticity’ signed by the Museum director. Mr. Corbacho is acting also in Spain as a judicial expert in paleontology while he is not more than an amateur fossil collector. In Peru, the two cited pseudo-paleontologists lead their official-looking businesses, the ‘Meyer-Honninger Palaeontological Museum’ and the ‘Peruvian Institute of Paleovertebrate Studies’, respectively, under names of institutional appearance. The ‘scientific research’ activities of Mr. Honninger have been basically deactivated by authorities of the Ministry of Culture, and following a public complaint for fraud in the First International Symposium of Palaeontology of Peru held in 2014 in Lima. However, the dealings of the Mr. Vildoso, who has long claimed to have a title on Paleontology from the University of La Plata (Argentina), which he has never been able to show, has experienced a considerable increase, with paleontological heritage contracts with mining companies and the organization of the Dakar Rally. The prominence of the position he has attained is such that he was offered the presidency of the Organizing Committee of the IX Latin American Congress of Palaeontology held in 2016 in Lima, which has ended in an organization disaster and a money scandal.

Giant postembryonic stages of Hydrocephalus and Eccaparadoxides and the origin of lecithotrophy in Cambrian trilobites

The early postembryonic stages of the Cambrian paradoxidid trilobites Hydrocephalus carens and Eccaparadoxides pusillus show an extraordinary morphology, which is characterised by an inflated glabella and reduced fixigenae. Moreover, the earliest known instars of both taxa are significantly larger than postembryonic instars of most of other Cambrian trilobites. Based on the size and morphology, we suggest that H. carens possessed a lecithotrophic type of development. This hypothesis is supported by growth patterns, accelerated development and frequency of distribution of H. carens. Lecithotrophic development is also proposed for E. pusillus, although the data are less convincing in this case. Analysis of early postembryonic instars of other Cambrian trilobites shows a correlation between their size and palaeogeographic distribution. The appearance of the largest postembryonic instars, including H. carens and E. pusillus, correlates with higher latitudes along the West Gondwanan margin. The specific environment in this area associated with unpredictable production of planktonic food is probably responsible for evolution of lecithotrophic development in these trilobite taxa.

Deep Endichnial Cruziana from the Lower-Middle Ordovician of Spain — A Unique Trace Fossil Record of Trilobitomorph Deep Burrowing Behavior

Full reliefs of Cruziana furcifera from the Lower-Middle Ordovician quartzite sandstone beds (Pochico Formation, southern Spain) points to deep, infaunal burrowing of trilobites. Some specimens show an unusual vertical extension with a wider lower part and a narrower upper part in cross section. They are referred to trilobites, which burrowed deeply in the sediment and were oriented obliquely head down and tail up. Deep burrowing seems to be common for other members of the Cruziana rugosa group, foremost C. rugosa and C. furcifera, less for C. goldfussi. The deep burrowing recorded in the discussed trace fossils can be referred to the earliest common infaunalization caused by trilobites and other arthropods during the Ordovician, probably in a response to a food competition on the sea floor, which promoted a behavioral plasticity within the same taxon or closely related taxa of trilobites.

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.

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

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.

PRELIMINARY REPORT ON THE NEW FINDINGS OF MISSISSIPPIAN TRILOBITES IN THE BŘEZINA FORMATION (MORAVIAN KARST, CZECH REPUBLIC)

New fossiliferous layers of the Březina Formation were discovered in the valley of the Říčka Brook SSW of the village of Ochoz u Brna in 2011. Four taxa of trilobites were preliminary determined: Archegonus (Phillibole) cf. polleni (Woodward, 1894), Archegonus (Phillibole) cf. cauliquercus Brauckmann 1981, Liobole (Liobole) glabra proxima Chlupáč, 1966 and ?Spinibole sp. The newly discovered fossiliferous beds belong to the Viséan (Lower to ?Upper Viséan, approximately cu IIγ–cu IIδ). The occurrence of limestone pebbles and limestone cobbles in aleuropelitic shales was also recorded. The Late Tournaisian foraminifer Darjella monilis Malakhova, 1964 was discovered in a dark grey limestone cobble derived from the Hády-Říčka limestone sequence of the Líšeň Formation.

First record ofTelephina(Trilobita) from the Ordovician of northeastern Estonia and its stratigraphical implications

For the first time a telephinid trilobite was recorded from the shallow-water rocks of the North Estonian Confacies Belt in the oil-shale mining area of northeast Estonia. A cranidium of Telephina (Telephops) biseriata (Asklund) was collected from a loose boulder of the kerogenous limestone of the Viivikonna Formation, Kukruse Stage, together with a rich assemblage of other trilobites, bryozoans, ostracods and rare graptolites. In its type area Jamtland, Sweden, T. biseriata occurs together with Pygodus anserinus and Hustedograptus teretiusculus in the Staltorp Limestone Member of the Anderso Shale Formation, marking the latest Darriwilian. The occurrence in the North Estonian Confacies Belt of Telephina, known as a pelagic trilobite inhabiting deeper-water areas, probably reflects a transgression event at this time. Together with T. biseriata, other trilobite taxa such as Remopleurides and Lonchodomas, common in the Hustedograptus teretiusculus Biozone in deeper-water areas, arrive in the North Estonian Confacies Belt. Graptolites from the other loose boulders at the same locality have been identified as Hustedograptus cf. uplandicus, which occur together with a few dendroids.

Trilobites of thePseudokoldinioidiaFauna (Uppermost Cambrian) from the Taebaek Group, Taebaeksan Basin, Korea

ThePseudokoldinioidiaFauna is a newly documented uppermost Cambrian trilobite assemblage from the Dongjeom Formation of the Taebaek Group, Taebaeksan Basin, Korea. It is characterized by low species diversity comprising six trilobite taxa:Micragnostus chiushuensis, Koldinioidia typicalis, leiostegiid genus and species indeterminate,Pseudokoldinioidia perpetis, Onychopyge borealis, and pilekiid genus and species indeterminate. Of these, special attention has been paid toPseudokoldinioidia perpetis, which was originally assigned toMissisquoia, an index fossil for the uppermost Cambrian in Laurentia.Pseudokoldinioidiais restricted to eastern Asia, whereasMissisquoiais confined to Laurentia. The appearance of thePseudokoldinioidiaFauna is interpreted as contemporaneous with the base of the‘Missisquoia’ perpetisZone of North China, which in turn is correlated with the base of theMissisquoia typicalisSubzone of Laurentia. The associatedKoldinioidiaandOnychopygemake it possible to compare thePseudokoldinioidiaFauna of Korea and North China with the latest Cambrian trilobite assemblages of South China, Australia, South America, and Mexico, and also suggests an interesting biogeographic connection among these areas in the latest Cambrian.

Systematics, palaeoenvironments and stratigraphy of the Silurian trilobite Dalmanites wandongensis Gill, 1948 and its bearing on the structural geology of the Kilmore area, Victoria

One of the most prolific trilobites in the mid-Palaeozoic of central Victoria is the dalmanitid Dalmanites wandongensis Gill, 1948. Extensive museum collections permit a revised diagnosis and a redescription of the species, and an interpretation of its distribution. The affinities of D. wandongensis lie with South American species assigned to Dalmanites and the closely related Kasachstania rather than northern hemisphere taxa including the D. caudata group. It occurs between Heathcote and Yan Yean in central Victoria, in late Wenlock and early Ludlow (Silurian) strata of the Dargile Group, on the eastern margins of the Melbourne Zone; its greatest abundance is between Kilmore and Wandong, where it is documented from over fifty localities, occurring rarely with other trilobite taxa. At Heathcote, Upper Plenty, Yan Yean and Kilmore East D. wandongensis stratigraphically underlies a more diverse trilobite fauna dominated by the encrinurid Cromus simpliciculus. This trilobite faunal succession defines a significant macrofaunal biostratigraphic datum in the sequence, complementing brachiopod and graptolite zonations. This datum is coincident with a subtle but widespread change in lithology that defines the lithostratigraphic boundary between the Yan Yean Formation and the Melbourne Formation. In the structurally complex and poorly exposed sequences of the Kilmore East area the distribution of D. wandongensis is used as a primary tool in mapping the distribution of these units. Outcrop patterns reveal the presence of two large scale east-northeast-oriented faults traversing the area that support a model of deformation for the Melbourne Zone in which transverse shearing is significant. Taphofacies and biofacies distribution in the Yan Yean Formation indicate a deep-water shelf depositional environment, at depths below maximum storm-wave base in the Kilmore-Wandong area, deepening eastwards, with outer shelf environments between Yan Yean and Christmas Hills.

Cambrian biostratigraphy of the Tal Group, Lesser Himalaya, India, and early Tsanglangpuan (late early Cambrian) trilobites from the Nigali Dhar syncline

Precise biostratigraphic constraints on the age of the Tal Group are restricted to (1) a basal level correlative with the Anabarites trisulcatus–Protohertzina anabarica Assemblage Zone of southwest China, (2) a level near the boundary of the lower and upper parts of the Tal Group correlative with the early Tsanglangpuan Stage (Drepanuroides Zone), and (3) an interval low in the upper part of the Tal Group correlative with later in the Tsanglangpuan Stage (Palaeolenus Zone). These correlations are based on small shelly fossil and trilobite taxa. Other chronostratigraphic constraints include the marked negative δ13C isotopic excursion coincident with the transition from the Krol Group to the Tal Group. This excursion is used as a proxy for the Precambrian–Cambrian boundary in several sections worldwide and, if applied to the Lesser Himalaya, indicates that the boundary is at or just above the base of the Tal Group. The upper parts of the Tal Group may be of middle or late Cambrian age and might form proximal equivalents of sections in the Zanskar–Spiti region of the Tethyan Himalaya. Both faunal content and lithological succession are comparable to southwest China, furthering recent arguments for close geographic proximity between the Himalaya and the Yangtze block during late Neoproterozoic and early Cambrian time. Trilobites from the uppermost parts of the Sankholi Formation from the Nigali Dhar syncline are described and referred to three taxa, one of which, Drepanopyge gopeni, is a new species. They are the oldest trilobites yet described from the Himalaya.

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.

A new soft-bodied fauna: The Pioche Formation of Nevada

A new Burgess Shale-type soft-bodied fauna crossing the Lower-Middle Cambrian boundary in the Comet Shale Member of the Pioche Formation in Lincoln County, Nevada, contains common remains of soft-bodied ecdysozoan taxa. These fossils provide important new information about the nature and variety of Cambrian soft-bodied organisms. Arthropod taxa include one species of Canadaspis Novozhilov in Orlov, 1960, one species of ?Perspicaris Briggs, 1977, three species of Tuzoia Walcott, 1912, and at least two species of Anomalocaris Whiteaves, 1892. A priapulid referable to Ottoia Walcott, 1911a, was also recovered. A comprehensive review of Tuzoia is given. Some specimens from Early Cambrian sections are replaced by hematite, resulting in iron staining similar to that in such other Early Cambrian soft-bodied faunas as the Kinzers Formation in Pennsylvania. Some taxa in the Comet Shale, and in other Early and Middle Cambrian soft-bodied faunas, have prodigious geographic ranges that spanned much of Laurentia and even other Cambrian cratons. Moreover, these taxa ranged across the Early-Middle Cambrian boundary relatively unscathed. This is in contrast to many trilobite taxa that had narrow geographic ranges in the Early Cambrian and high levels of extinction at the Early-Middle Cambrian boundary.

Phylogeny of the Reedocalymeninae (Trilobita): implications for Early Ordovician biogeography of Gondwana

Abstract The shallow-water Neseuretus Association has been recognized by many authors as an important indicator of the former extent of Gondwana during the Early Ordovician. Phylogenetic relationships of the Reedocalymeninae (Arenig-?Early Silurian) were investigated using cladistic analysis, incorporating 22 species of Neseuretus as well as representatives of all other reedocalymenine genera. The area cladogram derived from this analysis contains four subclades each containing areas that span much of the palaeogeographic extent of Gondwana, which are interpreted as representing separate biogeographic events during the evolution of the subfamily. As the majority of taxa included in the analysis are associated with shallow shelf facies, this suggests that no significant environmental barriers existed across the continent during the Early Ordovician. Consideration of area relationships both for different subclades within the area cladogram, and within a consensus area cladogram, also supports the idea of a faunal cline between eastern and western Gondwana during this time interval. Further cladistic analysis of different trilobite taxa can be used to test these ideas.

Facies of a Lower Ordovician carbonate shelf (Mungok Formation: Taebaeksan Basin, Korea)

The lithologic associations within the Lower Ordovician Mungok Formation in Korea define four depositional facies that formed across a continental margin fringing the Sino-Korean block: these facies represent lagoonal/restricted marine, shoal, inner shelf, and outer shelf environments. The stacking pattern of these facies reveals two systems tracts composed of five depositional sequences. The lower highstand systems tract consists of the lagoonal/restricted marine and shoal facies, whereas the upper lowstand systems tract comprises, in ascending order, inner shelf, outer shelf, and inner shelf facies. Three trilobite biofacies are recognized in the Mungok Formation: i.e.,Yosimuraspis, Kainella, andShumardia biofacies in ascending order. TheYosimuraspis Biofacies is dominated byYosimuraspis but also containsJujuyaspis andElkanaspis. The predominance of the endemic eponymous taxon suggests a lagoonal/restricted marine environment. The nearly monotaxicKainella Biofacies, which comprises pandemic genera such asKainella and occasionallyLeiostegium, may represent a less restricted environment than theYosimuraspis Biofacies. TheShumardia Biofacies occurs in the marlstone/shale lithofacies through relatively thick stratigraphic interval and is dominated by cosmopolitan trilobite taxa with some endemic species. The lithofacies and cosmopolitan trilobite assemblage of theShumardia Biofacies indicate that it occupied an outer shelf environment. The vertical succession of lithofacies and trilobite biofacies in the Mungok Formation records in general a shift from a restricted, shallow water environment to deeper-water environment.

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.