Furongian Trilobites Research Articles

The first systematic description of Cambrian fossils from Myanmar: Late Furongian trilobites from the southern part of the Shan State and the early Palaeozoic palaeogeographical affinities of Sibumasu

The existence of late Cambrian (Furongian) trilobites in Myanmar (Burma) has been acknowledged since the 1970s, but no formal systematic descriptions of such fossils have been published to date. Herein, we provide such descriptions of some trilobites from the Molohein Group’s Myet-Ye Formation from the Linwe area, Ye-Ngan Township of the southern Shan State. Three species from two genera are reported: Asioptychaspis (A. asiatica, previously known from the North China Block, and a new species, A. lata) and Eosaukia buravasi, also known from peninsular Thailand. The Molohein Group was initially assigned a late Cambrian age based on the reported, but unsubstantiated, occurrence of the Laurentian genera Saukiella and Drumaspis, and this age assessment is supported by the fauna we present, although Saukiella or Drumaspis remain unconfirmed from Myanmar. Asioptychaspis asiatica first appears in late Jiangshanian strata, and Eosaukia buravasi ranges up to the middle of Stage 10. Thus these ranges provide a more specific constraint on the age of the Molohein Group. Similarities are strong between upper Cambrian and Lower Ordovician successions in Sibumasu and northwestern Australia, particularly those from the Canning Basin succession. Regional geological data supports placement of Sibumasu adjacent to Western Australia during the Cambrian, without the Lhasa Block intervening between them, and Baoshan at the western end of Sibumasu during the early Paleozoic, towards the Himalayan margin. The new Burmese fauna is consistent with these suggestions, as they belong to the Sino-Australian faunal province.

Satunarcus, a new late Cambrian trilobite genus from southernmost Thailand and a reevaluation of the subfamily Mansuyiinae Hupé, 1955

AbstractThe Ao Mo Lae Formation of the Tarutao Group crops out on Thailand's Tarutao Island and contains a diverse assemblage of late Furongian trilobite taxa, including several endemic forms. This study presents a new genus and species, Satunarcus molaensis, discovered at two locations on the island. A cladistic analysis of the kaolishaniid subfamily Mansuyiinae in light of Satunarcus and similar genera known from across upper Cambrian equatorial Gondwanan rocks suggests that the subfamily is polyphyletic in its current definition, and thus is not a natural group. Separating Mansuyia Sun, 1924 from the other taxa conventionally placed in Mansuyiinae permits recognition of a previously unrecognized monophyletic subfamily Ceronocarinae new subfamily. As established herein, this kaolishaniid subfamily contains Satunarcus n. gen. and all genera previously recognized as Mansuyiinae. with the exception of Mansuyia itself. Ceronocarinae n. subfam. occur in middle Jiangshanian to middle Cambrian Stage 10 sedimentary rocks from Australia, South China, North China, and Sibumasu, with most genera endemic to Australia.UUID: http://zoobank.org/618c5136-73f0-4912-a7d3-e56559d2a76c

Elviniid trilobites from the Elvinia Zone (late Cambrian, Furongian) of Mendoza, western Argentina

AbstractIn the 1950s, Carlos Rusconi reported the biostratigraphically important Furongian trilobites Elvinia Walcott and Irvingella Ulrich and Resser from an exotic limestone block (La Cruz Olistolith) of the San Isidro area, Precordillera of Mendoza, western Argentina. Although several local species were erected by Rusconi at that time, most of them were later listed as junior synonyms of E. roemeri (Shumard) or I. major Ulrich and Resser, and this was followed in subsequent studies. A systematic revision of all the available specimens of Elvinia and Irvingella from the Rusconi collection at the Museo de Ciencias Naturales y Antropológicas J.C. Moyano (Mendoza) is provided herein. The occurrence of E. roemeri is supported by the present study, while the associated Irvingella species include I. jorusconii Rusconi, I. platycephala Rusconi, and Irvingella sp. The latter represent “advanced” forms in terms of morphological development in the Irvingella lineage, and these, together with E. roemeri, are typical of the uppermost part of the Elvinia Zone (uppermost Steptoean). Irvingella jorusconii, I. platycephala, and Irvingella sp. appear to be endemic to the Argentinian Precordillera, but are related to species from central Texas and northwest Canada.

Some middle and late Cambrian trilobites and brachiopods from the Adamsfield Trough, Tasmania

Jago, J.B., Bentley, C.J., Laurie, J.R. & Corbett, K.B., 26 June 2018. Some middle and late Cambrian trilobites and brachiopods from the Adamsfield Trough, Tasmania. Alcheringa 43, 1-17. ISSN 0311-5518.Cambrian Series 3 and Furongian trilobites and brachiopods are described from the Adamsfield Trough in southwestern Tasmania. The oldest fossils are very poorly preserved trilobites, assigned to Asaphiscidae gen. et sp. indet. from within the Island Road Formation a short distance above the unconformity with the underlying Proterozoic Wedge River Beds. A trilobite species from within the isolated Boyd River Formation is referred to Lioparia sp. The Island Road Formation and the Boyd River Formation are stratigraphically equivalent to the Trial Ridge Beds which have previously been dated as belonging to the Lejopyge laevigata Zone. The Trial Ridge Beds are overlain unconformably by the Singing Creek Formation. In the Adamsfield, Clear Hill and Stepped Hills areas, stratigraphic equivalents of the Singing Creek Formation collectively contain the trilobites Pseudaphelaspis sp., Pseudaphelaspis? sp., Prochuangia sp., Mindycrusta sp., Nepeidae gen. et sp. indet., and Olenidae gen. et sp. indet. plus the brachiopods described herein as Billingsella sp. aff. costata, Billingsella sp. A, Billingsella sp. B and a possible member of the Billingselloidea. The Singing Creek Formation has been previously correlated with the Stigmatoa diloma Zone. The genus Lotosoides Shergold 1975 is placed in synonymy with Prochuangia Kobayashi 1935.James B. Jago* [jim.jago@unisa.edu.au] University of South Australia, School of Natural and Built Environment, Mawson Lakes, SA 5095, Australia; Christopher J. Bentley [bigfossil@bigpond.com] 30 Albert Street, Clare, SA 5453, Australia; John R. Laurie [john.r.laurie@gmail.com] Department of Biological Sciences, Macquarie University, NSW 2109, Australia; Keith D. Corbett [keith.corbett@bigpond.com] 35 Pillinger Drive, Fern Tree, Tas 7054, Australia.

A late Furongian trilobite assemblage from the eastern Cordillera Oriental (Santa Rosita Formation; Jujuy, Argentina) and its biostratigraphic significance

The trilobite Parabolina frequens argentina Zone is widely represented in the upper Furongian of northwestern Argentina. A fossil assemblage from the lower Santa Rosita Formation at Quebrada de Abra Blanca, Jujuy Province, is described herein. Parabolina frequens argentina (Kayser) and Parabolinella coelatifrons Harrington & Leanza have previously been reported from other localities of the biozone, whereas Lotagnostus hedini (Troedsson) is here described from South America for the first time. The latter provides high resolution data on the age of the P . frequens argentina Zone in the eastern Cordillera Oriental, where conodont-bearing strata have not been found yet. L . hedini exhibits a short biostratigraphic range, restricted to the latest Furongian of China (Xinjiang, Bulbolenus Zone; western Zhejiang, Lotagnostus hedini Zone), Kazakhstan ( Euloma limitaris - Taoyuania Zone) and ?Canada (western Newfoundland, Phylacterus saylesi Fauna). In China and Kazakhstan, it occurs in association with, or a few meters below, the first appearance of the conodont Cordylodus proavus ; a fact that increases the potential for global correlation.

Upper Cambrian (Furongian) biostratigraphy in Scandinavia revisited: definition of superzones

The traditional Furongian trilobite biozones of Scandinavia, recently proposed abandoned due to inconsistent boundary definitions [Terfelt, F., Eriksson, M.E., Ahlberg, P. & Babcock, L.E., 2008: Furongian Series (Cambrian) biostratigraphy of Scandinavia – a revision. Norwegian Journal of Geology88, 73–87], are resurrected and elevated to superzonal rank. These superzones are usually readily recognized in the field, even by non-specialists, and for general correlation and mapping the more wide-ranging biozones are considerably more practicable than the very detailed zonation (formerly subzonation) introduced by Terfelt et al. (2008). Formal definition of the superzones is outlined including designation of stratotype sections. The superzones are each defined by the FAD of a characterizing species group and upwards delimited by the base of the succeeding superzone. The long used Olenus, Parabolina and Leptoplastus (super)zones as well as the recently introduced Acerocarina Superzone ( = Acerocare Zone of older literature) are maintained and formalized. The Protopeltura praecursor, Peltura minor and Peltura scarabaeoides zones are abandoned and replaced by two new units, named the Protopeltura and Peltura superzones, respectively. Accordingly, all Furongian superzones have a uniform naming style referring to a characteristic genus. The six Furongian superzones currently comprise 27 trilobite zones. The Paradoxides forchhammeri Superzone (Cambrian Series 3) is extended upwards to the base of the Olenus Superzone, thereby formally including the Agnostus pisiformis Zone.

Mansuyia Sun, and Tsinania Walcott, from the Furongian of North China and the evolution of the trilobite family Tsinaniidae

AbstractThe Furongian trilobite family Tsinaniidae is characterized by a highly effaced surface and forms an important constituent of the Furongian trilobite faunas of east Gondwana. However, the origin of the characteristic morphology of this family has remained unclear. Only recently has the tsinaniid trilobite Lonchopygella megaspina been suggested to represent an intermediate stage in the evolutionary transition to other tsinaniids on the basis of the trunk segmentation. Here, we report successive occurrences of four species of the kaolishaniid genus Mansuyia and a tsinaniid trilobite Tsinania canens from the Furongian (late Cambrian) Chaomidian Formation in Shandong Province, China. A cladistic analysis including these taxa reveals that the four species of Mansuyia constitute stem‐group taxa to the family Tsinaniidae, rendering Mansuyia and the Kaolishaniidae paraphyletic. The youngest species of Mansuyia, M. taianfuensis, turns out to be the immediate sister taxon of the Tsinaniidae, displaying a closely similar morphology to the tsinaniid trilobite, Shergoldia laevigata. The generic and familial boundary therefore situated between M. taianfuensis and S. laevigata.

Dikelocephalid trilobites from theEosaukiafauna (Upper Furongian) of the Taebaek Group, Korea

TheEosaukiafauna is proposed for the upper Furongian trilobite assemblage from the interval spanning from the upper part of the Hwajeol Formation to the lowermost part of the Dongjeom Formation in the Taebaek Group, Taebaeksan Basin, Korea. It is characterized by the dominance of dikelocephalid trilobites comprisingEosaukia micropora, E. bella, E. acuta, Mictosaukiacf.M. globosa, andTaebaeksaukia spinatan. gen. n. sp. Taxonomic reappraisal of the genusMictosaukiathat has been employed as an upper Cambrian index taxon in eastern Gondwana reveals that more than half of the species ofMictosaukiabelong inEosaukia.This study clarifies the generic concept ofEosaukia, which provides a more reliable biostratigraphic correlation for the upper Furongian strata in eastern Gondwanan regions. TheEosaukiafauna is correlated with the“Mictosaukia”faunas from the upper Fengshanian of North China, upper Taoyuanian of South China, and upper Payntonian of Australia.

Furongian trilobites from theAsioptychaspis andQuadraticephalus zones of the Hwajeol Formation, Taebaeksan Basin, Korea

This paper describes the upper Furongian trilobites from the Hwajeol Formation and, based on these trilobite faunal assemblages, proposes formally two trilobite biozones, theAsioptychaspis andQuadraticephalus zones. A total of 14 species belonging to ten genera are described: i.e.,Micragnostus sp.,Pseudagnostus planulatus, Koldinioidia sp.,Hamashania pulchera, Hamashania sp. cf.H. busiris, Asioptychaspis subglobosa, Changia sp.,Quadraticephalus elongatus, ptychaspidid genus and species indeterminate,Lophosaukia orientalis, Lophosaukia? sp.,Tsinania canens, Tsinania sp., andHaniwa sosanensis. TheAsioptychaspis Zone is characterized by predominance ofAsioptychaspis subglobosa, while the succeedingQuadraticephalus Zone is dominated byQuadraticephalus elongatus, Lophosaukia orientalis, Haniwa sosanensis, andMicragnostus sp. TheAsioptychaspis andQuadraticephalus zones are well correlated with thePtychaspis- Tsinania andChangia (orQuadraticephalus) zones of North China, respectively. These two trilobite assemblages of the Hwajeol Formation support a strong paleogeographical link between the Taebaeksan Basin and North China Platform during the late Furongian.

Occurrence of Changshania (Trilobita, Cambrian) in the Taebaeksan Basin, Korea and its stratigraphic and paleogeographic significance

In the Cambrian the Taebaeksan Basin was a shallow marine siliciclastic–carbonate system, in which two contrasting types of lithofacies and biofacies occur in juxtaposition. The shallow marine facies (Taebaek Group) comprises diverse trilobite taxa endemic to the Sino–Korean block, whereas the deep-water oceanic facies (Yeongwol Group) is characterized by predominance of cosmopolitan and pelagic trilobites. Changshania is a representative Furongian trilobite genus endemic to the Sino–Korean block and has been employed as a zonal taxon for middle Furongian in North China. This article reports the occurrence of Changshania from the deep-water facies (Machari Formation, Yeongwol Group) of the Taebaeksan Basin, for the first time in Korea. This observation enables to correlate the Eochuangia hana Zone of Korea with the Changshania– Irvingella Zone of North China with confidence. The dominance of laminated dark gray to black shale and pandemic trilobites in the Machari Formation has been interpreted to indicate deposition in a dysaerobic deep-water environment. The occurrence of Changshania along with some endemic polymerid trilobites, though uncommon, in the deeper-water oceanic facies suggests that the Machari Formation was formed in the offshore region fringing the Sino–Korean block during the Cambrian.