Trilobite Fauna Research Articles

First record of trilobites (Arthropoda) from Carboniferous deposits of the Dnipro-Donets Depression, north-eastern Ukraine

A small trilobite faunule consisting of Weberides mucronatus (M’Coy, 1844) and Waribole sp. is described from Serpukhovian (Upper Mississippian) strata of the Sribne-Krasnograd Zone in the Dnipro-Donets Depression (north-eastern Ukraine). Weberides mucronatus has previously been recorded from Serpukhovian levels in the Donets Basin and in the Lviv Palaeozoic Trough in Ukraine, whereas species of Waribole are here recorded from Carboniferous deposits of Ukraine for the first time. This genus is typical of faunal assemblages of the Mississippian-aged Kulm facies, formed under relatively deep-water marine conditions and widely distributed across western and central Europe.

Taxonomy and stratigraphic distribution of Lotagnostus (Agnostida: Agnostidae) and associated trilobites and conodonts in the Upper Cambrian (Furongian) of Laurentia.

Two Lotagnostus-dominated faunas from the Windfall Formation at Ninemile Canyon in the Antelope Range of Nevada, USA, are described: an older Lotagnostus nolani Fauna and younger L. rushtoni Fauna. The former is dominated by two morphs of Lotagnostus, one strongly scrobiculate and the other smooth to weakly scrobiculate. Both morphs fall within the broad concept advocated for L. americanus by Peng et al. (2015). The numerous (>1400 sclerites) specimens of Lotaganostus in collections of the L. nolani Fauna confirm that the two morphs do not intergrade and remain distinct throughout ontogeny. Both display multiple traits that distinguish them from the type material of L. americanus, justifying treatment as separate species. Similarly unique, diagnostic features were identified to restore the Asian species L. punctatus and L. asiaticus to full species status, whereas deficiencies in the type material for L. americanus warrant restriction of the name to the holotype. New species described from the Windfall include five agnostoids (Lotagnostus nolani, L. clarki, L. morrisoni, L. rushtoni, and Neoagnostus parki) and one trilobite (Bienvillia eurekensis). Plicatolina nyensis Taylor is reassigned to Mendoparabolina on the form of its pygidium. Conodonts from the Catlin Member of the Windfall Formation and overlying informal Caryocaris shale member of the Goodwin Formation at Ninemile Canyon provide a late Sunwaptan (Eoconodontus Zone) age for the Lotagnostus rushtoni Fauna and assign the entire Caryocaris shale to the early Ordovician Rossodus manitouensis Zone. Combined with published data on trilobite faunas, the conodont faunas confirm strong diachroneity for the top of the Catlin, and a lack of overlap in age between the Caryocaris shale and Bullwhacker Member of the Windfall in ranges to the north and east. Co-occurrence of Lotagnostus nolani and Mendoparabolina nyensis establishes age equivalence of the L. nolani Fauna with the Hedinaspis-Charchaqia (HC) Fauna at the base of the Hales Limestone in the Hot Creek Range, and earlier correlations of the latter with the L. punctatus Zone in Asia are supported. However, isolation of the HC Fauna in starved-basin deposits above a major sequence boundary at the base of the Hales, and ecologic restriction of Lotagnostus to lower slope and basinal environments that prevented association with endemic shallow marine taxa, renders correlation into the biostratigraphy of Laurentian upper slope and platform imprecise on the order of 10s, if not 100s of meters.

Trilobites from the Al Rose Formation (Lower Ordovician, Inyo Mountains, California)—faunas marginal to the Great Basin

Abstract The Lower Ordovician (Floian) Al Rose Formation from the Inyo Mountains, California, is a deeper-water, graptolitic equivalent of the well-known and richly fossiliferous successions described from Utah and Nevada. It is considered to have been originally marginal to the Laurentian paleocontinent. It has yielded a low-diversity trilobite fauna that differs strikingly from contemporary faunas to the east in its abundance of raphiophorid, nileid, olenid, and agnostoid trilobites, resembling that of the Nileid Biofacies known from scattered locations marginal to Laurentia. Two new trilobite species are described: Globampyx sexsegmentatus (Raphiophoridae) and Protopresbynileus divergens (Nileidae). Carolinites genacinaca Ross, 1951 is a link with the Great Basin. Other trilobites include the olenid Cloacaspis cf. C. ceryx anataphra Fortey, 1974, metagnostid Geragnostus cf. G. (Novoagnostus) longicollis Raymond, 1925, and pliomerid Hintzeia sp. UUID: https://zoobank.org/19a679ce-968d-4ce1-a590-f7f55bf9d62d

Diversity dynamics, faunal turnover and radiation pattern of the Middle Ordovician trilobites in South China

Available data on the temporal and geographical distribution of Middle–early Late Ordovician trilobites in South China were reviewed under a high-resolution biostratigraphical framework to investigate the diversity dynamics and explain the faunal turnover and radiation pattern of trilobites during the Middle Ordovician. Three macroevolutionary phases are recognized on the basis of the diversity changes at taxonomic levels. Cluster analysis shows three trilobite groups, two distinct trilobite faunas and three faunal turnovers through nine time slices. Three trilobite groups (Groups A, B and C) are coupled with three macroevolutionary phases, and characterized by different proportions of the Whiterock Fauna. Two distinct trilobite faunas (Early–Middle Ordovician and Late Ordovician Trilobite Faunas) and three faunal turnovers could be recognized at different similarity coefficients, their replacements were mainly affected by changes of sea level and substrate conditions. The trilobite radiation was manifested by the development, expansion and domination of the Whiterock Fauna (part of the Paleozoic Evolutionary Fauna) through the Middle Ordovician. The first diversity acme of trilobites occurred during the Dapingian–early Darriwilian, while the radiation centre gradually shifted from inner platform to outer platform environments. From the end Darriwilian onwards, elements of the Whiterock Fauna had further developed and dominated all environmental settings from the inner platform to the lower slope, coinciding with the second and more extensive radiation of trilobites in South China. Two phases of radiation may have been directly triggered by two major transgressions during the late Dapingian–early Darriwilian and the late Darriwilian–early Sandbian respectively. In addition, climate cooling and various substrate conditions, as well as the increased oxygen levels in the atmosphere and marine water, nutrients and tectonic movements during the Middle Ordovician may have provided essential conditions for the trilobite radiation.

Katian (Late Ordovician) trilobites of the North Qilian Mountains and their palaeogeographical implications for the Proto‐Tethys Archipelagic Ocean

AbstractTrilobites from the middle Koumenzi Formation (Katian, Upper Ordovician) of the North Qilian Mountains, Menyuan, northeastern Qinghai Province are systematically documented for the first time. The fauna consists of five families, seven genera and seven species, one of which is new (Remopleurides zhangi), showing a close relationship to those of the Kazakh terranes (such as the Chu‐Ili terrane, Chingiz‐Tarbagatai area and the Karatau‐Naryn and North‐Tien Shan microcontinents), and the North China and Laurentia palaeoplates during the Katian (Late Ordovician). The cluster and non‐metric multidimensional scaling analyses of the Middle–Late Ordovician (late Darriwilian–Katian) trilobite faunas with 299 genera or subgenera from 46 horizons of 37 areas, provide valuable information for the palaeogeographical reconstruction of the Proto‐Tethys Archipelagic Ocean (PTAO) of this interval. The Qilian terrane and adjacent areas are essential components of the PTAO, some of which include the Qilian terrane, the North Qilian Mountains area, the Altun faulted terrane, the Hexi Corridor area and the East Qinling terrane. Their relative positions in the PTAO are inferred by the palaeobiogeography of trilobite faunas. Furthermore, based on discussions of the spatiotemporal distribution of those faunas, the Pliomerina and/or Sinocybele Province of the Middle–Late Ordovician (late Darriwilian–Katian) age is defined as a trilobite faunal province of the PTAO. Moreover, a distinct faunal subprovince, essentially comprising the South China Palaeoplate and its neighbours (e.g. Tarim, Annamia, Sibuma, East Qinling, Turkestan‐Alai and probably Talesh), might be surrounded by the equatorial cold‐water tongue.

Trilobites of Thailand's Cambrian–Ordovician Tarutao Group and their geological setting

AbstractTuff‐bearing upper Cambrian to lowermost Ordovician strata on Ko Tarutao island, Satun province, southernmost peninsular Thailand, contain a rich trilobite fauna relevant to global biostratigraphy, peri‐Gondwanan palaeogeography and shifting evolutionary mode. This area of Sibumasu, a lower Palaeozoic marginal Gondwanan terrane, is shown to have been closely associated with Australia, North China (Sino‐Korea) and other continental fragments from the supercontinent's northern equatorial sector, including South China at that time. Shared faunas also suggest a Kazakhstani and Laurentian association. Collections from eight sections yielded 10 newly discovered species and one new genus from ancient shoreface and inner shelf siliciclastic deposits. With the new taxa and revision of taxa known previously, we refine the age of the upper two formations of the Tarutao Group to the middle of Cambrian Stage 10, and lower–middle Tremadocian. Two biozones are erected for Sibumasu: the Eosaukia buravasi Zone, encompassing all Cambrian sections from Ko Tarutao, and the Asaphellus charoenmiti Zone, encompassing the Tremadocian fauna discussed herein. The new genus is Tarutaoia and new species are Tsinania sirindhornae, Pseudokoldinioidia maneekuti, Pagodia? uhleini, Asaphellus charoenmiti, Tarutaoia techawani, Jiia talowaois, Caznaia imsamuti, Anderssonella undulata, Lophosaukia nuchanongi and Corbinia perforata. Other taxa reported for the first time from Tarutao are Mansuyia? sp., Parakoldinioidia callosa Qian, Pseudagnostus sp., Homagnostus sp., Haniwa mucronata Shergold, Haniwa sosanensis? Kobayashi, Lichengia simplex Shergold, Pacootasaukia sp., Wuhuia? sp., Plethopeltella sp., Apatokephalus sp., Akoldinioidia sp. 1 and Koldinioidia sp.

Stratigraphy of the Cambrian (Miaolingian to Furongian) and Ordovician (Tremadocian) west of Arivechi, eastern Sonora, Mexico: Implications on the Cambrian-Ordovician boundary

The Cambrian-Ordovician transition in Mexico has been poorly documented. According to the literature published until now, the most complete middle-upper Cambrian (Miaolingian to Furongian)-Lower Ordovician (Tremadocian) (509-477 Ma) succession is exposed near the town of Arivechi, in northeastern Sonora. This Cambrian-Ordovician sedimentary succession is approximately 900 m thick and is divided into seven lithostratigraphic units. The Cambrian portion of the section consists of El Gavilán, El Mogallón, Milpillas, and La Huerta formations (∼600 m) and range from the upper Wuliuan to Paiban stages (509-494 Ma). El Gavilán Formation consists of limestone and shale with chancelloriids and trilobites of the Altiocculus Subzone of the upper Ehmaniella Zone (Miaolingian, Wuliuan). El Mogallón formation (informal name) is characterized by shale, siltstone, and limestone with abundant poriferans and agnostids of the Ptychagnostus atavus/Bolaspidella Zone (Miaolingian, Drumian). Milpillas formation (informal name) consists of limestone and sandy limestone with trilobites of the Crepicephalus Zone (Miaolingian, Guzhangian). La Huerta formation (informal name) is a limestone and shale intercalations with abundant brachiopods, including Angulotreta triangularis, indicative from the Aphelaspis to the lower Dunderbergia Zones (Furongian, Paibian). The Lower Ordovician (Tremadocian) portion of the section consists of El Santísimo formation herein informaly divided into three members: El Ranchito, El Encinal and La Palma (∼300 m). El Ranchito member consists of limestone, shale, and siltstone with dendroid graptolites of Anisograptus matanensis Zone (Early Ordovician, Tremadocian). El Encinal member consists of siltstone and sandstone with cross-stratification and graptolites of Anisograptus matanensis Zone (Early Ordovician, Tremadocian). La Palma member contains in the lower non-fossiliferous part, a limestone breccia and siltstone, and the upper part contains limestone with conodonts from the Rossodus manitouensis to the Scolopodus subrex Zone (Early Ordovician, Tremadocian). The Cambrian deposits of eastern Arivechi represent open marine platform facies with an abundant fauna of poriferans, brachiopods, trilobites, and echinoderms, typical of Laurentia. In contrast, the Ordovician deposits represent open ocean deposits dominated by graptolites and conodonts that indicate a shallow marine to a shelf environment.

A Jiangshanian (Cambrian; Furongian) trilobite fauna from the Cow Head Group, western Newfoundland

Three shelf-derived boulders in debris flow conglomerates of the Downes Point Member of the Shallow Bay Formation of western Newfoundland yielded the first record of an Upper Cambrian shelf-margin trilobite fauna from the Elvinia Zone (Steptoean; Jiangshanian) in eastern North America. The fauna is dominated by the “catillicephalid” Buttsia Wilson, 1951, and resembles trilobite biofacies from microbial buildups in the Gatesburg Formation of Pennsylvania. It is correlative with the Cliffia latagenae Subzone, which is the youngest Steptoean biostratigraphic unit in the Gatesburg. New taxa are Triorygma burkhalteri gen. et sp. nov. and Buttsia trema sp. nov.

A new Cambrian (Jiangshanian, Sunwaptan) trilobite fauna from Oklahoma and its biostratigraphic significance.

AbstractThe Cambrian (Jiangshanian, Sunwaptan) Honey Creek Formation in the Wichita Mountains region of Oklahoma yielded a new fauna dominated by Monocheilus Resser, 1937 (senior synonym of Stigmacephalus Resser, 1937) in association with Ptychaspis Hall, 1863. It occupies the same stratigraphic position as similar faunas in the Upper Mississippi Valley and Alberta, lying a little above an interval characterized by species of Taenicephalus Ulrich and Resser in Walcott, 1924 and Orygmaspis Resser, 1937. Revision of Ptychaspis bullasa Lochman and Hu, 1959 from type material from Idaho and sclerites attributed to the species from Texas reveals a plexus of pseudocryptic species that share tuberculate sculpture on the cranidium. New species are Monocheilus reginae, Monocheilus richardi, Ptychaspis occulta, and Ptychaspis matuszaki.UUID: www.zoobank.org/c2771c63-db4b-434a-ae58-3e3fda19ecb0

Systematics and biostratigraphy of a new trilobite fauna collected from the subsurface Earlie Formation (Wuliuan Stage, Miaolingian Series, Cambrian) in southwestern Saskatchewan

Trilobites were recovered from four cores of the middle Cambrian Earlie Formation in southwestern Saskatchewan. Fossils occur in silty mudstone with interbedded siltstone and limestone, deposited in the inner detrital belt of the craton interior, under low-energy, subtidal conditions. Taxa identified include Kootenia dawsoni (Walcott 1889), Asaphiscus wheeleri Meek 1873, Blainia gregaria Walcott 1916b, Parehmania princeps Deiss 1939b, Ehmania weedi Resser 1935, Bolaspis labrosa (Walcott 1916a), and corynexochid gen. and sp. indet., indicating an age ranging from the lower to upper Altiocculus subzone of the Ehmaniella Zone, upper Wuliuan Stage. The upper Eldon and lower Pika formations located farther west in subsurface Alberta and the Rocky Mountains are considered to be age equivalent. Biostratigraphy confirms that strata overlying the Basal Sandstone Unit are diachronous and become progressively younger eastward. The trilobite fauna is lower in diversity relative to those in temporally equivalent units in the Rocky Mountains as well as the Great Basin, indicating that it may have experienced some environmental stressors, and that seafloor colonization was sporadic and opportunistic.

Revealing new trilobites from the early Devonian alto garças sub-basin, Brazil

ABSTRACT The composition of the trilobite fauna from the Devonian Paraná Basin in Brazil is still not fully elucidated. Although rich literature on the southern portion of this basin, the northwestern part has been poorly explored. In this study, we reveal new taxa and provide a comprehensive taxonomic composition of malvinoxhosan trilobites collected from the PragianEmsian sediments of Alto Garças Subbasin, Brazil. We report Burmeisteria notica, Metacryphaeus australis, Pennaia pauliana, Calmonia signifer and Kozlowskiaspis subseciva, well known elements from the southern portion of the Paraná Basin. Metacryphaeus meloi, unprecedented in the Paraná Basin, reveals itself here in the oldest biostratigraphic position in relation to other specimens reported from the Cabeças Formation (Frasnian-Famennian, Parnaíba Basin). We reveal a new species of Bainella, here described as Bainella (Belenops) sulmatogrossensis sp. nov. We discuss the biostratigraphic position of components of this fauna and their correlation with other Devonian units. Taking all together, our work provides a new picture about the trilobite taxonomic composition in the northwestern portion of the Paraná Basin, and can help our understanding of speciation pulses and dispersion patterns among the different Devonian basins in Gondwana.

Lower Ordovician Trilobites from SE Sardinia (Italy): A new record of the “Taihungshania bioprovince”

A systematic description of the so far unique trilobite fauna and the associated biota from the Arenarie di San Vito Formation, in the outcrops close to the abandoned Tacconis mine (allochthonous nappe zone, Sarrabus, SE Sardinia, Italy), proves the occurrence of Taihungshania shui landayranensis, Ampyx priscus, Asaphellus sp., Merlinia sp., Niobe fourneti?, Geragnostus sp. and Symphysurus sp., accompanied by several taxa of graptolites, ichnofossils and less common bivalves, gastropods, cephalopods and hyolithids. The taphonomical signature, sedimentary structures and “Raphiophorid biofacies” clearly argue for an early Floian age and a median platform (i.e., offshore to shoreface) depositional environment. The occurrence of T. shui landayranensis in Sardinia allows us to determine the age of the Arenarie di San Vito Formation (just below the Sarrabese unconformity) and to discuss the palaeobiogeographical affinities highlighting the value of the “Taihungshania bioprovince”. The Tacconis trilobite fauna displays close affinities with Montagne Noire in France, Taurides in Turkey, Alborz in Iran, and south China, placing the SE Sardinia allochthonous area in a global Ordovician palaeogeographic sketch. A brief discussion on relationships and palaeobiogeographical affinities between the Sardinian nappe zone and the autochthonous “foreland” Sulcis-Iglesiente, which are adjacent today, strongly suggests a separation during the Ordovician, although both areas pertain to the Gondwana margin.

Structural control of Cambrian paleotopography and patterns of transgression in western Laurentia

Abstract The Cambrian transgression across the Great Unconformity produced one of the largest expansions of shallow marine habitats and associated diversification of marine invertebrate faunas in Earth history. However, identification of the underlying controls on the pattern of transgression of Cambrian seas has been hampered by imprecise or inaccurate age assignments for many formations. Recovery of an Ehmaniella Zone trilobite fauna from the Lodore Formation in northwestern Colorado (United States) revises the age of this unit to be significantly older, specifically middle Miaolingian (upper Wuliuan). This expands the established distribution of thick Miaolingian deposits of the northern Rocky Mountains to within 90 km of a broad region of central Colorado where Miaolingian strata are missing and Furongian successions rest directly on basement. The boundary between these two regions marks the position of an ~200 km east-west offset within the generally north-south–trending Cambrian paleoshoreline of western North America. The offset is co-located with a Precambrian continental suture zone (Cheyenne belt) at the northern Yavapai terrane margin and is directly east of an offset of similar magnitude and latitude in the early to middle Paleozoic shelf edge in Nevada. We thus posit that Precambrian deep-seated crustal-scale features controlled the Cambrian paleotopography of western Laurentia, strongly influencing the patterns of Cambrian transgression and structure of the shallow marine ecosystem established during continental submergence. These continental-scale structural elements remained a major control on marine paleogeography for >200 m.y. into the late Paleozoic.

Biogeographic patterns in Late Paleozoic trilobites

Based on cluster and correspondence analysis, Late Paleozoic trilobites are shown to display varying degrees of provincialism and cosmopolitanism through time. These distributional changes appear to coincide temporally with the closing of the Rheic Ocean and the onset and waning of the Late Paleozoic Ice Age. Early Tournaisan trilobite faunas, composed mainly of primitive phillipsid genera, display widespread distribution within ancestral deep-water environments of the Rheic Ocean. Middle to late Tournaisian through early Viséan trilobite genera were segregated into environmentally constrained endemic shelf faunas, and widespread to cosmopolitan deep-water biota. Reduced provincialism during the Serpukhovian is interpreted to have resulted from the onset of the Late Paleozoic Ice Age. Initiation of this profound global environmental perturbation is interpreted to have produced equatorially constricted climate zones and rapidly vacillating sea level and cylothemic deposits that created high levels of ecological stress within marine faunas. Early Pennsylvanian trilobite faunas exhibited weak levels of provincialism on either side of Pangea, with dominant faunal components displaying cosmopolitan tendencies. Trilobite faunas of the late Pennsylvanian were characterized by a few widespread to cosmopolitan genera, that exhibit ecologic generalist tendencies while inhabiting broad geographic and latitudinal ranges. Permian trilobites exhibit a progressive increase in provincialism through time which is interpreted to be the result of the ending of the Late Paleozoic Ice Age and the onset of greenhouse conditions.

Biostratigraphical significance of a new trilobite fauna from the Harkless Formation (upper Stage 4, Series 2, Cambrian), Nevada, USA

Biostratigraphical significance of a new trilobite fauna from the Harkless Formation (upper Stage 4, Series 2, Cambrian), Nevada, USA

Trilobites of trinucleid, raphiophorid and cyclopygid associations from the Ordovician (Darriwilian – early Katian) of the west Balkhash region and Betpak‐Dala, Central Kazakhstan

AbstractMiddle to Late Ordovician (late Darriwilian –early Katian) trilobites from trinucleid, raphiophorid and cyclopygid biofacies are for the first time documented from the West Balkhash and North Betpak‐Dala regions in south‐central Kazakhstan. Twenty taxa are described; six of them, that is, Miaopopsis sokyrensis sp. nov., Pricyclopyge keralensis sp. nov., Kongqiaoheia sarytumensis sp. nov., Shumardia karasaiensis sp. nov., Triarthrus akkermensis sp. nov. and Mynaralaspis perforata gen. et sp. nov. are new to science. Six taxa are reported in open nomenclature and two are not identified on a genus level. A new trinucleid Subfamily Nanshanaspinae is designated. Newly discovered faunas show strong links to contemporaneous faunas of Tarim and, to a lesser degree, to those of South China and the Australian sector of Gondwana. Based on results of cluster analysis (Dice similarity), trilobite associations of raphiophorid biofacies from the Chu‐Ili and Stepnyak terranes form a single first‐order cluster with little similarity to the trilobite associations characteristic of the nielid and illenid–cheirurid biofacies from the Stepnyak and Tarbagatai regions. Also, there is no distinct interaction between the pelagic Degamella–Pricyclopyge association and other trilobite faunas. The geographical distribution of raphiophorid and trinucleid trilobites described in this paper, including species of genera Malongullia?, Miaopopsis, Nanshanaspis and Kongqiaoheia, supports Ordovician palaeogeographical reconstructions showing the Kazakh terranes as part of a huge archipelago situated on both sides of the equator in proximity to the west coast of Gondwana and positioned a considerable distance from the Siberia continent and its associated terranes.

Biostratigraphy of the Ribota and Huérmeda formations (Cambrian Series 2) in the Comarca del Aranda (Zaragoza province), Iberian Chains (NE Spain)

This article presents a detailed biostratigraphic analysis of the Cambrian Series 2 Ribota and Huérmeda formations of four sections of the Iberian Chains (NE Spain), and a systematic study of their trilobite faunas. We identified four major assemblages: two in the middle part of the Ribota Formation, one at the base of the Huérmeda Formation and one at the top of the Huérmeda Formation. The studied species permit the assignment of these formations to the middle and upper Marianian and probably lower Bilbilian stages in the regional stratigraphic chart for the Iberian Peninsula, which correlates with an interval around the Cambrian Stage 3–4 boundary. The assemblages exhibit a great correlation potential with the presence of Termierella and the first figured material of Andalusiana from the Iberian Chains, two characteristic taxa of the Marianian of the Ossa-Morena Zone, having been also recorded from the Central Iberian Zone and Morocco. In addition, specimens tentatively assigned to Hebediscus are recorded for the first time from the region, a taxon with a wide geographic distribution which allows a good international correlation in the Cambrian Series 2.

Biostratigraphy and paleoecology of the trilobite faunas from the Mount Clark and Mount Cap formations (early and middle Cambrian), eastern Mackenzie Mountains, northwestern Canada

AbstractLower and middle Cambrian strata of the eastern Mackenzie Mountains, Northwest Territories, Canada, were deposited in a semi-enclosed basin along the eastern flank of the Mackenzie Arch. The Mount Clark Formation is predominantly composed of nearshore sandstone and is overlain by deeper water siltstone, mudstone, and carbonates of the Mount Cap Formation. The contact between these formations is interpreted as a flooding surface. Trilobite biostratigraphy indicates the presence of the traditional upper Olenellus through Glossopleura zones (Cambrian Series 2, Stage 4–Miaolingian, Wuliuan) and suggests the flooding surface is diachronous, spanning the Dyeran-Delamaran boundary. Above the Olenellus Zone, the Amecephalus arrojosensis-Eokochaspis nodosa Zone, the new Aitkenaspis keelensis Zone, the new Albertelloides mischi Zone, and the Glossopleura walcotti Zone are recognized. Whereas the older zones are comparable to those in other areas of Laurentia, the trilobite faunas in the Albertelloides mischi and Glossopleura walcotti zones show a greater abundance of zacanthoidids and dolichometopids. They also have a lower diversity of ptychoparioids and oryctocephalids, and lack agnostoids, eodiscoids, dorypygids, and ogygopsidids. This suggests that zacanthoidids and dolichometopids were able to tolerate conditions that were unfavorable to the other groups, probably related to semi-restricted conditions in the basin. Four endemic species exhibit characteristics that are considered paedomorphic. This developmental process took place in three separate lineages, suggesting that heterochrony was also environmentally provoked.New taxonomic names are authored by Handkamer and Pratt. New genera are Eobathyuriscus, Sahtuia, Mexicaspidella Aitkenaspis, Dodoella, and Mackenzieaspis. New species are Bolbolenellus dodoensis, Eobathyuriscus mackenziensis, E. macqueeni, Glossopleura youngi, Sahtuia carcajouensis, Aitkenaspis keelensis, Albertelloides eliasi, Dodoella kobayashii, Mackenzieaspis parallelispinosa, and M. divergens.UUID: http://zoobank.org/a10a2470-853c-4ce8-bf62-7de1d2c99fab.

Cambrian (Stage 4 to Wuliuan) brachiopods from Sonora, Mexico

AbstractThe Cambrian successions at the Chihuarruita Hill outcrop, Sonora, Mexico, have yielded two successive linguliform brachiopod assemblages that are transitional between Cambrian Stage 4 and the newly recognized global Wuliuan Stage. The lowermost assemblage includesDictyoninasp.,Paterinasp.,Eothelesp.,Hadrotreta rara? (Cooper), andLinnarssonia arellanoi? (Cooper), coming from the upper part of the Buelna Formation. The younger, recently named El Gavilán Formation contains a more diverse linguliform brachiopod assemblage, includingAcrothele concavaCooper,Batenevotreta?mexicanan. sp.,Dictyonina minutipunctaCooper,Eothelesp.,Eoobolussp.,Hadrotreta rara? (Cooper),Linnarssonia arellanoi? (Cooper),Micromitrasp.,Paterinasp., andPrototretasp. The El Gavilán Formation contains a diverse trilobite fauna suggesting Delamaran age in terms of the Laurentian regional stratigraphical scheme. The base of the global Wuliuan Stage and Miaolingian Series is defined by the first occurrence ofOryctocephalus indicus; in the absence of the index species, the base should be provisionally placed at the base of the El Gavilán Formation. The Wuliuan age of the brachiopod assemblage recovered from the El Gavilán Formation is supported by the occurrence ofAcrothelein the Cambrian biostratigraphical succession of Himalaya, where the genus makes its first appearance in theKaotaia prachinaZone. In addition, the co-occurrences ofAcrotheleandEothelecan be taken as an indication of the Wuliuan age of the fauna. A new biogeographic analysis confirms that theEotheleFauna first appeared at the end of Cambrian Stage 4, as a result of increased faunal migration within the southern tropical latitudes directed from Australasian Gondwana to Laurentia.UUID:http://zoobank.org/6598f51f-cb07-4df3-bd1f-025a13e64edf

PROFESOR VALERIAN MYKOLAYOVYCH WEBER — OUTSTANDING GEOLOGIST-SURVEYER AND EXPERT IN TRILOBITES (to the 150th Аnniversary of his birth)

Valerian Мykolayovych Weber (1871—1940) entered the history of geological science of the former USSR and the world as an outstanding geologist-surveyor, a prominent paleontologist, a specialist in trilobite fauna and Paleozoic stratigraphy, a teacher and organizer of science, an active member of scientific geological societies. He was the discoverer of a number of deposits of iron and copper-arsenic-lead ores, coal, and oil. The scientist studied the classical sections and fauna of the Paleozoic of Western Europe, carried out geological surveys in sultry Turkestan. As a geologist, Valerian Mykolayovych traveled and studied regions of Central Asia, Urals, Crimea, Caucasus, Pamirs, Novaya Zemlya, Svalbard, the Timan Ridge and the Far East. Of particular importance for him were the unique Paleozoic sections of the Donetsk folded structure. The scientist is the author of the monographs “Field Geology”, “Mineral Resources of Turkestan” and the geology of the Cheleken Peninsula, he is also known as a seismologist — he studied the Andijan, Akhalkalaki and Shemakha earthquakes. However, paleontological studies of trilobites brought world fame to the scientist. In total, for Permian, Devonian, Ordovician, and Silurian trilobites, V.M. Weber wrote six original monographs and more than ten articles. The first large monograph by V.M. Weber was the book “Trilobites of Turkestan”, then “Trilobites of Donbass” and a series of consolidated monographs on the Carboniferous trilobites of the USSR. The monograph by V.M. Weber “Trilobites of Donbass” contains material on trilobites collected by scientists from continuous, “reference” sections of marine carboniferous deposits of the Donets Basin. Paleontological works by V.M. Weber cover a wide range of geological time — from the Ordovician to the Permian inclusive. They are important for the stratigraphy of the sedimentary strata of the Carboniferous Donbas of Central Asia, Urals, Caucasus, Crimea and other geological regions of the USSR.