| 1. |
- Streng, Michael, 1971-, et al.
(författare)
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Columnar shell structures in early linguloid brachiopods : new data from the Middle Cambrian of Sweden
- 2008
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Ingår i: Earth and Environmental Science Transactions of the Royal Society of Edinburgh. - 1755-6910. ; 98:Part 3-4, s. 221-232
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Tidskriftsartikel (refereegranskat)abstract
- The records of columnar shell structures of linguloid brachiopods (Class Lingulata, Order Lingulida, Superfamily Linguloidea) are reviewed in the light of the discovery of two new taxa from the Middle Cambrian Forsemölla Limestone Bed of southern Sweden. The linguloid taxa, described here as Eoobolus? sp. aff. E. priscus (Poulsen) and Canalilatus? simplex sp. nov., are both characterised by a columnar shell structure, a structural type that is representative for acrotretoid brachiopods and that has previously only rarely been reported from the linguloids. Though the two taxa are superficially similar to known genera, i.e., Eoobolus and Canalilatus, their shell structure challenges such affiliations, as the shell structure of the type species of these genera is previously unknown. Linguloid families whose morphological characteristics agree the most with those of the new taxa, i.e., the Zhanatellidae and the Eoobolidae, and from which columnar shell structures have been reported, i.e., the Lingulellotretidae and the Kyrshabaktellidae, are reviewed briefly. Many taxa assigned to these families completely lack shell structure data and are in need of restudy in order to elucidate their systematic position. Knowledge of the representative type of shell structure of the various suprageneric taxa within the Linguloidea is considered crucial, in order to unravel their currently poorly resolved phylogenetic relationships.
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| 2. |
- Álvaro, J. Javier, et al.
(författare)
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Global Cambrian trilobite palaeobiogeography assessed using parsimony analysis of endemicity
- 2013
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Ingår i: Early Palaeozoic Biogeography and Palaeogeography. - 0435-4052. - 9781862393738 ; Memoir 38:38, s. 273-296
-
Bokkapitel (refereegranskat)abstract
- Palaeobiogeographical data on Cambrian trilobites obtained during the twentieth century are combined in this paper to evaluate palaeoceanographic links through c. 30 myr, once these arthropods biomineralized. Worldwide major tectonostratigraphic units are characterized at series intervals of Cambrian time and datasets of trilobite genera (629 for Cambrian Series 2, 965 for Cambrian Series 3, and 866 for the Furongian Series) are analysed using parsimony analysis of endemicity. Special attention is given to the biogeographical observations made in microcontinents and exotic terranes. The same is done for platform-basinal transects of well-known continental margins. The parsimony analysis of endemicity analysis resulted in distinct palaeogeographical area groupings among the tectonostratigraphic units. With these groupings, several palaeobiogeographical units are distinguished, which do not necessarily fit the previously proposed biogeographical realms and provinces. Their development and spatial distributions are broadly controlled by Cambrian palaeoclimates, palaeogeographical conditions (e.g. carbonate productivity and anoxic conditions) and ocean current circulation.
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| 3. |
- Álvaro, J. Javier, et al.
(författare)
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Submarine metalliferous carbonate mounds in the Cambrian of the Baltoscandian Basin induced by vent networks and water column stratification
- 2022
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Two massive precipitation events of polymetallic ore deposits, encrusted by a mixture of authigenic carbonates, are documented from the Cambrian of the semi-enclosed Baltoscandian Basin. δ34S (‒9.33 to ‒2.08‰) and δ33S (‒4.75 to ‒1.06‰) values from the basal sulphide breccias, sourced from contemporaneous Pb–Zn–Fe-bearing vein stockworks, reflect sulphide derived from both microbial and abiotic sulphate reduction. Submarine metalliferous deposits were triggered by non-buoyant hydrothermal plumes: plumes of buoyant fluid were trapped by water column stratification because their buoyancy with respect to the environment reversed, fluids became heavier than their surroundings and gravitational forces brought them to a halt, spreading out laterally from originating vents and resulting in the lateral dispersion of effluents and sulphide particle settling. Subsequently, polymetallic exhalites were sealed by carbonate crusts displaying three generations of ikaite-to-aragonite palisade crystals, now recrystallized to calcite and subsidiary vaterite. Th of fluid inclusions in early calcite crystals, ranging from 65 to 78 ºC, provide minimum entrapment temperatures for carbonate precipitation and early recrystallization. δ13Ccarb (‒1.1 to + 1.6‰) and δ18Ocarb (‒7.6 to ‒6.5‰) values are higher than those preserved in contemporaneous glendonite concretions (‒8.5 to ‒4.7‰ and ‒12.4 to ‒9.1‰, respectively) embedded in kerogenous shales, the latter related to thermal degradation of organic matter. Hydrothermal discharges graded from highly reduced, acidic, metalliferous, and hot (~ 150 ºC) to slightly alkaline, calcium-rich and warm (< 100 ºC), controlling the precipitation of authigenic carbonates.
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| 4. |
- Hairapetian, Vachik, et al.
(författare)
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Ordovician of the Anarak Region : implications in understanding Early Palaeozoic history of Central Iran
- 2015
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Ingår i: Stratigraphy. - 1547-139X .- 2331-656X. ; 12:2, s. 22-30
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Tidskriftsartikel (refereegranskat)abstract
- The Pol-e Khavand area south-east of the town of Anarak preserves important clues for understanding geological evolution of Central Iran during the Palaeozoic. New observations confirm the non-conformable relationship between Doshakh metamorphites and overlying unmetamorphosed Lower Palaeozoic sediments, suggesting accretion of the volcanic arc in front of the Yazd block sometime in the late Cambrian to early Ordovician. The newly introduced volcano-sedimentary Polekhavand Formation preserves evidence of a ?Late Cambrian to Early Ordovician post-collisional bimodal volcanism and related extensional regime in the Pol-e Khavand area during that time. The Middle to Upper Ordovician interval of the studied succession is assigned to the newly introduced Chahgonbad Formation. The Darriwilian age of the base of this lithostratigraphical unit is demonstrated by the brachiopods Tritoechia and Yangtzeella which co-occur with a diverse a cephalopod assemblage. The low diversity fauna including brachiopods Hibernodonta sp., Hindella sp., Rostricellula cf. ambigena and trilobites Vietnamia cf. teichmulleri suggest a Katian age for the upper part of the unit. There is insufficient evidence for the existence of the hypothetical Palaeo Tethys suture zone south of the Pol-e Khavand area.
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| 5. |
- Harper, David A.T., et al.
(författare)
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Brachiopods : origin and early history
- 2017
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Ingår i: Palaeontology. - : Wiley. - 0031-0239 .- 1475-4983. ; 60:5, s. 609-631
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Tidskriftsartikel (refereegranskat)abstract
- Despite many major advances in recent years, three key challenges remain in bringing clarity to the early history of the phylum: (1) identifying the origin, morphology and life modes of the first brachiopods; (2) understanding the relationships of the major groups to each other and higher sister taxa; and (3) unravelling the roles of the Cambrian and Ordovician radiations that set the agenda for much of subsequent brachiopod evolution. Since some 95% of all brachiopod taxa are extinct, the fossil record is the primary source of data to frame and test models for the evolution of the phylum. The acquisition of new, and the redescription of existing faunas, in precise spatial and temporal frameworks, using new and well-established analytical and investigative techniques, are as important as ever.
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| 6. |
- Holmer, Lars E., 1960-, et al.
(författare)
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Cambrian rhynchonelliform nisusioid brachiopods : phylogeny and distribution
- 2019
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Ingår i: Papers in Palaeontology. - : John Wiley & Sons. - 2056-2799 .- 2056-2802. ; 5:3, s. 559-575
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Tidskriftsartikel (refereegranskat)abstract
- A comprehensive review and phylogenetic analysis of genera and species presently assigned to the rhynchonelliform superfamily Nisusioidea and family Nisusiidae suggests that this short-lived but important group of brachiopods first appeared in peri-Gondwana during the second half of the Cambrian Series 2, before going extinct by the end of Drumian times. Nisusiides achieved their maximum morphological disparity and geographical distribution during the Wuliuan Age, and Laurentia was probably the major centre of their dispersal. A new phylogenetic analysis suggests an early separation of the lineages of spinose and non-spinose nisusiids. The non-spinose nisusiids probably evolved in Laurentia by the end of Cambrian Series 4. The new nisusiid genus Bellistrophia is described. The new species Nisusia multicostata represents the first documented rhynchonelliform (kutorginide) brachiopod from the Miaolingian (Drumian) of the Alborz Mountains, Iran.
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| 7. |
- Holmer, Lars E., 1960-, et al.
(författare)
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Cambrian (Stage 4 to Wuliuan) brachiopods from Sonora, Mexico
- 2022
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Ingår i: Journal of Paleontology. - : Cambridge University Press. - 0022-3360 .- 1937-2337. ; , s. 1-21
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Tidskriftsartikel (refereegranskat)abstract
- The 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 includes Dictyonina sp., Paterina sp., Eothele sp., Hadrotreta rara? (Cooper), and Linnarssonia 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, including Acrothele concava Cooper, Batenevotreta? mexicana n. sp., Dictyonina minutipuncta Cooper, Eothele sp., Eoobolus sp., Hadrotreta rara? (Cooper), Linnarssonia arellanoi? (Cooper), Micromitra sp., Paterina sp., and Prototreta sp. 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 of Oryctocephalus 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 of Acrothele in the Cambrian biostratigraphical succession of Himalaya, where the genus makes its first appearance in the Kaotaia prachina Zone. In addition, the co-occurrences of Acrothele and Eothele can be taken as an indication of the Wuliuan age of the fauna. A new biogeographic analysis confirms that the Eothele Fauna 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.
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| 8. |
- Holmer, Lars E, et al.
(författare)
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Early Ordovician organophosphatic brachiopods with Baltoscandian affinities from the Alay Range, southern Kyrgyzstan
- 2000
-
Ingår i: GFF. - : Informa UK Limited. - 1103-5897 .- 2000-0863. ; 122:4, s. 367-375
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Tidskriftsartikel (refereegranskat)abstract
- Organophosphatic-shelled brachiopods (Subphylum Linguliformea, Class Lingulata) of early Ordovician (Arenig) age are described for the first time from carbonate olistoliths within the Silurian Pulgon Formation of the Kichik Alay Range, southern Kyrgyzstan. The assemblages include Paterula? naukatensis sp. nov., Rowellella sp., Orbithele ceratopygarum (Brgger), Acrotreta korynevskii Holmer & Popov, Ombergia mirabilis gen. et sp. nov., Eoconulus cf.primus Popov & Holmer, and Palaeoglossa? aff. razumovskii (Lermontova). The Kyrgyzstanian faunas appear to correlate mainly with assemblages from the upper Hunnebergian or lower Billingenian regional stages of Baltoscandia. Taxa in common with those from the early Arenig of Baltoscandia and the South Urals include O. ceratopygarum and A. korynevskii. Ombergia mirabilis is known otherwise only from coeval strata in Baltoscandia. It is probable that the Kyrgyzstanian olistoliths originated from early Ordovician intra-oceanic volcanic island arcs in the proximity of Gondwana, and the microbrachiopod faunas around these islands may have given rise to the more widespread and richer faunas that spread across Baltica during the rest of the Ordovician, as the island complexes drifted towards Baltica.
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| 9. |
- Holmer, Lars E., et al.
(författare)
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Ecology, biofacies, biogeography and systematics of micromorphic lingulate brachiopods from the Ordovician (Darriwilian–Sandbian) of south-central China
- 2017
-
Ingår i: Papers in Palaeontology. - : Wiley. - 2056-2799 .- 2056-2802. ; 3:3, s. 317-361
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Tidskriftsartikel (refereegranskat)abstract
- Ordovician (Darriwilian to Sandbian) micromorphic linguliform lingulate brachiopods are described from the Guniutan Formation at the Fenxiang section in Hubei province, and the Maocaopu and Cili sections in Hunan province of south-central China, situated on the Yangtze Platform. A total of 7560 specimens from 155 limestone samples (within the interval of Lenodus variabilis – Pygodus anserinus biozones) are assigned to 22 species, representing a low taxonomic diversity and low abundance fauna. The fauna is dominated by the Acrotretoidea, mainly species of the Torynelasmatidae, with Torynelasma the most abundant (more than 40% of total number of specimens), along with the Eoconulidae and Eoconulus (18% of total) representing the second most common forms. Species of the Ephippelasmatidae are also common (16% of total) diverse, and include representatives of Myotreta and Numericoma, as well as Ephippelasma, whereas species of the Scaphelasmatidae are somewhat less common (13% of total). All three investigated sections represent outer shelf environments, but the Maocaopu section is situated in a relatively deeper position, in proximity of the south-eastern outer margin of the Upper Yangtze Platform, close to its boundary with the Jiangnan Slope. A quantitative analysis of the relative abundance data was carried out in order to investigate the biofacies distribution of the micromorphic brachiopod communities across the Yangtze Platform, something that has not been attempted before with Palaeozoic linguliforms. Six lingulate microbrachiopod communities could be recognized in the sections. The major biofacies shift, which occurred in the Cili section in the upper part of the Microzarkodina ozarkodella Zone, at the time of the onset and initial rise of the Mid Darriwilian Carbon Isotope Excursion (MDICE) suggests that these biofacies may have been depth controlled.
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| 10. |
- Holmer, Lars E., 1960-, et al.
(författare)
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Evolutionary significance of a middle Cambrian (Series 3) in situ occurrence of the pedunculate rhynchonelliform brachiopod Nisusia sulcata
- 2018
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Ingår i: Lethaia. - : Scandinavian University Press / Universitetsforlaget AS. - 0024-1164 .- 1502-3931. ; 51:3, s. 424-432
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Tidskriftsartikel (refereegranskat)abstract
- Exceptionally preserved, silicified and articulated complete shells of the rhynchonelliform kutorginate brachiopod Nisusia sulcata are redescribed from the middle Cambrian (Series 3) Marjum Limestone, Utah. Cylindroid sausage-like protrusions, emerging posteriorly between the valves, were originally interpreted as faecal in origin, but restudy under the SEM shows that these features represent silicified pedicles as they are attached in situ to other Nisusia. The Nisusia host most likely was alive at the time of attachment. Restudy of the pedicles of Nisusia provides new phylogenetic information on the anatomy of the earliest rhynchonelliforms. The silicified pedicles differ considerably from the pedicles of living crown group rhynchonelliforms in being strongly annulated, distally tapering, and were likely to have been rather more flexible. The Nisusia pedicles are more similar to the exceptionally preserved pedicles from other Cambrian rhynchonelliform brachiopods, including Kutorgina, Longtancunella and Alisina, but these emerge from the ventral apical foramen rather than from between the valves as in Nisusia. Although generally similar, these two types of pedicles are unlikely to represent homologous structures as Nisusia is provided with both an apical foramen (possibly larval attachment) and a posterior adult pedicle. The similarities may be explained by similar type of accretionary growth from two different types of epithelia. The Nisusia-like pedicle appeared early within the kutorginates and rhynchonellates. The discovery of hollow spines in Nisusia sulcata further supports the generic assignation of the species.
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| 11. |
- Holmer, Lars E., 1960-, et al.
(författare)
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Linguliform brachiopods from the Cambrian (Guzhangian) Karpinsk Formation of Novaya Zemlya
- 2020
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Ingår i: Papers in Palaeontology. - : John Wiley & Sons. - 2056-2799 .- 2056-2802. ; 6:4, s. 571-592
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Tidskriftsartikel (refereegranskat)abstract
- Abstract A moderately diverse assemblage of micromorphic linguliform brachiopods, including Tapuritreta gribovensis sp. nov., Wahwahlingula? pankovensis sp. nov., Acrothele sp., Anabolotreta? sp., Orbithele? sp. and Stilpnotreta sp., is for the first time described from the Cambrian Karpinsk Formation (Miaolingian, Guzhangian) of the South Island of Novaya Zemlya. The morphology of the metamorphic shell in Acrothele and Wahwahlingula? suggest that both taxa had a single pair of larval setal sacs, similar to the recent discinids, but their metamorphosis was completed only at the end of the pelagic stage and shows that they did have direct development, which is characteristic of all recent lingulides. The biogeographical signature of the new Cambrian brachiopod fauna from Novaya Zemlya is discussed, and the new fauna gives new information on the poorly known Cambrian margins of the Baltica palaeocontinent.
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| 12. |
- Holmer, Lars E., et al.
(författare)
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Lower Ordovician (Tremadocian) lingulate brachiopods from the House and Fillmore formations, Ibex Area, western Utah, USA
- 2005
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Ingår i: Journal of Paleontology. - 0022-3360 .- 1937-2337. ; 79:5, s. 884-906
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Tidskriftsartikel (refereegranskat)abstract
- Seven genera and eight species of lingulate brachiopods were recovered from the House Limestone and lower Fillmore Formation, Ibex area, Utah, USA. These strata are assigned to the upper Skullrockian Stage and lower Stairsian Stage of the Ibexian Series (Iapetognathus Conodont Zone to Low Diversity Interval) and are correlated with the Tremadocian Series of the Acado–Baltic Faunal Province. The fauna includes two new linguloid species, Spinilingula prisca and Wahwahlingula sevierensis, one new siphonotretoid species, Schizambon obtusus, and two new acrotretoid species, Eurytreta fillmorensis and Ottenbyella ibexiana. The last species is the first record of the genus in North America and suggests a correlation of the basal Fillmore Formation with the Ceratopyge Limestone in Sweden. A Siphonobolus? covered by long hollow spines may be one of the oldest siphonotretides with such ornament. This fauna and those described previously from older Utah strata document the biodiversification of the Cambrian–Ordovician lingulate brachiopods and demonstrate their potential for regional and intercontinental correlation.
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| 13. |
- Holmer, Lars E., et al.
(författare)
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Reassessment of the early Triassic lingulid brachiopod ‘Lingula’ borealis Bittner, 1899 and related problems of lingulid taxonomy
- 2016
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Ingår i: GFF. - : Informa UK Limited. - 1103-5897 .- 2000-0863. ; 138:4, s. 519-525
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Tidskriftsartikel (refereegranskat)abstract
- The Early Triassic (late Induan to early Olenekian) Lingula borealis Bittner, from the Russkii Island on the Pacific cost of south-eastern Russia is revised, based on re-examination of the type material. Although this species, like most described Triassic lingulids, has remained very poorly understood due to the lack of information on important characters, such as musculature and mantle canals, it has been commonly recorded in subsequent studies and included in attempts at understanding the patterns of extinction and recovery at around the Permian-Triassic boundary. Linguliform brachiopods are some of the notable survivors of this significant mass extinction event. Lingula borealis has previously been referred to Lingularia and provisionally synonymised with Lingularia similis Biernat & Emig. Here, it is shown that it differs from Lingularia similis mainly in characters of mantle canals, musculature and most importantly in details of the pedicle nerve impression. In Lingularia borealis, the impression of the pedicle nerve is symmetrical and goes almost straight between the individual ventral umbonal muscle scars, whereas in Lingularia similis it is asymmetrically positioned towards the smaller left component of the ventral umbonal muscle scar. Shell structures and details of preserved ontogenies have also proven to be important for the discrimination of lingulid taxa, but cannot be provided from the types of Lingularia borealis.
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| 14. |
- Holmer, Lars E., 1960-, et al.
(författare)
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Unusual pitted Ordovician brachiopods from the East Baltic : the significance of coarsely pitted ornamentations in linguliforms
- 2017
-
Ingår i: Papers in Palaeontology. - : Wiley. - 2056-2799 .- 2056-2802. ; 3:3, s. 387-399
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Tidskriftsartikel (refereegranskat)abstract
- A characteristic coarsely pitted ornamentation (with pits larger than 0.015 mm across) can be found on some very enigmatic and rare Lower Ordovician phosphatic-shelled linguliform brachiopods, including the paterinid Lacunites balaschovae Gorjansky and the obolid Foveola maarduensis Gorjansky. Both of these species are poorly understood and known from only a few specimens from the Floian of the East Baltic. Here we describe the Ordovician species Lacunites ivantsovi sp. nov. from the lower Darriwilian of the St Petersburg region and Foveola ivari sp. nov. from the Sandbian of Estonia, representing the last known survivors of these genera in the area. The new Darriwilian species of Lacunites is also one of the last members of the Class Paterinata, which most importantly includes some of the earliest known brachiopods from the early Cambrian. The coarsely pitted ornamentation of Foveola ivari is associated with the formation of asymmetrical so-called terrace lines in the umbonal area. The latter may indicate a burrowing life style. The pits in Lacunites and Foveola are directly comparable to the more or less identical coarse pits in the discinoid Trematis. Unlike the microscopic pits found in many fossil linguliforms, it is most likely that the coarse pits were empty in life; the minute surface ornamentation of irregular wrinkles in the outer primary layer continues across the bottom of the depressions in Foveola and Trematis; in the latter the cementing attachment discs of an attached phosphatic tubular Byronia-like organism also extend down into the pits.
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| 15. |
- Jahangir, Hadi, et al.
(författare)
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Biostratigraphy of the Cambrian–Ordovician boundary beds at Kopet-Dagh, Iran
- 2015
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Ingår i: Stratigraphy. - 1547-139X .- 2331-656X. ; 2:12, s. 40-47
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Tidskriftsartikel (refereegranskat)abstract
- A continuous succession comprising upper Cambrian (Furongian) to Lower Ordovician (Tremadocian) conodont biozones is reported for the first time from the Kopet-Dagh Region of northeastern Iran. Seven biostratigraphical units are recognized, including the Proconodontus tenuiserratus and Proconodontus posterocostatus zones; these two lowermost biostratigraphical units are defined by euconodont species which have not been previously reported from Iran and temperate latitude peri-Gondwana. The conodont diversity and abundance decreased significantly above the Eoconodontus notchpeakensis Zone; the conodont faunas of the succeeding Cordylodus proavus, Cordylodus lindstromi (sensu lato) and Cordylodus angulatus zones are characterised by oligotaxic to monotaxic associations dominated by species of Cordylodus. In the absence of diagnostic conodont species, the position of the lower boundary of the Ordovician System in the Kalat Valley Section can be placed somewhat below the first occurrence of the early planktonic graptolite Rhabdinopora flabelliformis, which approximately coincides with the onset of black shale deposition.
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| 16. |
- Jahangir, Hadi, et al.
(författare)
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The siphonotretide brachiopod Schizambon from the Early Ordovician of South China : ontogeny and affinity
- 2023
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Ingår i: Papers in Palaeontology. - : John Wiley & Sons. - 2056-2799 .- 2056-2802. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- Schizambon is one of the earliest and most distinctive genera in the Order Siphonotretida. However, current knowledge of siphonotretide phylogeny and early evolution requires understanding of their earliest ontogeny. In this study, the new species Schizambon tongziensis from the Tungtzu Formation at Honghuayuan section in Guizhou Province, South China is described; it is also the first record of Schizambon in South China. The new well-preserved specimens shed light on the ontogeny, palaeobiogeographical distribution, phylogeny and early evolution of siphonotretide brachiopods. Characters of metamorphic shells on both valves, outlined by distinct halos, show that Schizambon had a planktotrophic ‘paterinide-type’ larva, typical of many early Palaeozoic brachiopods. Based on the newly obtained data it is inferred that the free-swimming larva of Schizambon settled directly on the ventral side of the body, and this type of ontogeny is probably true for other siphonotretides. The divergence of Schizambon from the main siphonotretide lineage probably happened prior to the Guzhangian Age, well before the occurrence of major biodiversification within the order.
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| 17. |
- Popov, Leonid E., et al.
(författare)
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Biogeography of Ordovician linguliform and craniiform brachiopods
- 2013
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Ingår i: Early Palaeozoic Biogeography and Palaeogeography. - : Geological Society of London. - 9781862393738 ; , s. 117-126
-
Bokkapitel (refereegranskat)abstract
- The biogeographical patterns shown by Ordovician linguliform and craniiform brachiopods are greatly influenced by their dominance in low-diversity associations in marginal environments. This is particularly evident in the Early Ordovician, when linguliform-dominated dysaerobic assemblages are widely distributed along the deep shelves of Gondwana, the Kazakhstanian terranes and in Baltica. By the Darriwilian, micromorphic linguliforms are characteristic components of the pantropical climatic-controlled faunas of Laurentia, Cuyania and Kazakhstanian terranes, which – in spite of separation by extensive oceans – retain a distinct similarity. Analysis of craniiform biogeographical distribution is impeded significantly by the poor state of craniide taxonomy and lack of reliable data from most regions. However, in general their biogeographical dispersion is similar to other groups of the Palaeozoic Evolutionary Fauna. Unlike the linguliforms, which are important members of the Cambrian Evolutionary Fauna, there is no convincing Cambrian craniiform record; they may have evolved and dispersed from Gondwana and associated microcontinents and island arcs. The earliest well-established record is from the late Tremadocian of temperate to high-latitude peri-Gondwana. During most of the Ordovician, they have a peri-Iapetus distribution. They are very rare or absent in tropical Gondwana, South China and Kazakhstanian terranes and are not yet documented from Siberia. The trimerellides probably evolved in tropical peri-Gondwanan island arc settings. Their dispersion and major features of biogeography mirror those of atrypides.
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| 18. |
- Popov, Leonid E., et al.
(författare)
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Cambrian (Furongian) rhynchonelliform brachiopods from the Eastern Alborz Mountains, Iran
- 2013
-
Ingår i: Bulletin of Geosciences. - : Czech Geological Survey. - 1214-1119 .- 1802-8225. ; 88:3, s. 525-538
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Tidskriftsartikel (refereegranskat)abstract
- The Cambrian (Furongian) shallow water carbonates in the Mila Formation in the Tuyeh-Darvar area (eastern Alborz, northern Iran) contain numerous shell beds, entirely composed of disarticulated valves of the billingsellide brachiopods Billingsella? fortis sp. nov. and Hyrcanostrophia tuyehensis gen. et sp. nov. Higher up in the Mila Formation, the shallow water carbonates are replaced by nodular limestones, deposited in an open marine environment, containing Palaeostrophia tecta Nikitin & Popov, 1983 and the early polytoechioid Darvaretoechia prisca gen. et sp. nov. These two different brachiopod assemblages are assigned to the oligotaxic Billingsella and Palaeostrophia associations, respectively. These associations are considered to represent precursors to the brachiopod-dominated benthic assemblages of the Palaeozoic Evolutionary Fauna. The new brachiopod faunas from the Alborz Terrane are closely similar to contemporaneous Furongian faunas from the Australasian sector of Gondwana, in particular, to those from South China and the Kazakhstanian terranes.
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| 19. |
- Popov, Leonid E., et al.
(författare)
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Earliest ontogeny of Early Palaeozoic Craniiformea : implications for brachiopod phylogeny
- 2010
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Ingår i: Lethaia. - : Scandinavian University Press / Universitetsforlaget AS. - 0024-1164 .- 1502-3931. ; 43:3, s. 323-333
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Tidskriftsartikel (refereegranskat)abstract
- Well preserved specimens of the Early Palaeozoic craniiform brachiopods Orthisocrania and Craniops retain clear evidence of a lecithotrophic larval stage, indicating the loss of planktotrophy early in their phylogeny. The size of the earliest mineralized dorsal shell was <100 mu m across, and the well preserved shell structure in these fossil craniiforms allows their earliest ontogeny to be compared directly with that of living Novocrania, in which the first mineralized dorsal shell (metamorphic shell) is secreted only after settlement of the lecithotrophic larvae. Immediately outside this earliest shell (early post-metamorphic or brephic shell) and in the rest of the dorsal valve the primary layer in both fossil and living craniiforms has characteristic radially arranged laths, which are invariably lacking in the earliest dorsal shell. The ventral valve of the fossil specimens commonly preserves traces of an early attachment scar (cicatrix), which is equal in size to the dorsal metamorphic shell, and the brephic post-metamorphic ventral valve also has a primary shell with radially arranged laths. However, a primary shell with radial laths is completely lacking in the ventral valve of living Novocrania, indicating that heterochrony may have been involved in the origin of the encrusting mode of life in living craniids; the entire ventral valve of Recent craniids (with the possible exception of Neoancistrocrania) may correspond to the earliest attachment scar of some fossil taxa such as Orthisocrania. It is also probable that the unique absence of an inner mantle lobe as well as the absence of lobate cells in Novocrania could be the result of heterochronic changes. The dorsal valve of both fossil and living craniiforms has a marked outer growth ring, around 500 mu m across, marking the transition to the adult, and a significant change in regime of shell secretion. The earliest craniiform attachment is considered to be homologous to the unique attachment structures described recently in polytoechioids (e.g. Antigonambonites) and other members of the strophomenate clade. However, unlike the craniiforms, polytoechioids and strophomenates all have planktotrophic larvae, and planktotrophy is most probably a plesiomorphic character for all Brachiopoda.
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| 20. |
- Popov, Leonid E., et al.
(författare)
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Earliest ontogeny of Middle Ordovician rhynchonelliform brachiopods (Clitambonitoidea and Polytoechioidea) : Implications for brachiopod phylogeny
- 2007
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Ingår i: Lethaia. - : Scandinavian University Press / Universitetsforlaget AS. - 0024-1164 .- 1502-3931. ; 40:1, s. 85-96
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Tidskriftsartikel (refereegranskat)abstract
- New data on the earliest ontogeny of Mid-Ordovician Baltoscandian clitambonitoid (Apomatella, Neumania and Oslogonites) and polytoechioid (Antigonambonites and Raunites) brachiopods reveal significant differences in the life history of the taxa belonging to these two superfamilies. The Polytoechioidea and probably other members of the Billingsellida had planktotrophic larvae, in which the dorsal and ventral mantle lobes formed separately and without reversion. The 'pedicle sheath' in Antigonambonites is secreted by a section of modified ventral mantle and thus this 'pedicle' is not homologous within the pedicle of rhynchonellate brachiopods. It is likely that polytoechioids and other members of the strophomenate clade had the same type of ontogeny and mode of attachment. In contrast, the ontogeny and mode of attachment of clitambonitoids are similar to that of recent rhynchonellates: their mantle lobes and both valves formed simultaneously, and the pedicle most likely formed from the larval pedicle lobe. Evidence for the lecithotrophic nature of clitambonitoid larva is discussed. This confirms that the Clitambonitoidea, unlike the Polytoechioidea, represents an ingroup within the Rhynchonellata.
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| 21. |
- Popov, Leonid E., et al.
(författare)
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Early ontogeny and soft tissue preservation in siphonotretide brachiopods : New data from the Cambrian-Ordovician of Iran
- 2009
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Ingår i: Gondwana Research. - : Elsevier BV. - 1342-937X .- 1878-0571. ; 16:1, s. 151-161
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Tidskriftsartikel (refereegranskat)abstract
- New Late Cambrian (Furongian) to Early Ordovician (Tremadocian) assemblages of micromorphic organo-phosphatic (linguliformean) brachiopods from Iran are characterised by the presence of exceptionally well preserved material of the Order Siphonotretida, a small, phylogenetically important group with a very poorly documented Cambrian history. Unlike other known Cambrian siphonotretides, which generally lack true spines, the new Iranian taxa preserve the constant presence of hollow spines from as early as the mid Late Cambrian. Early siphonotretide ontogeny remains poorly known, but new data from the Iranian faunas demonstrate that the dorsal larval shell had two pairs of lobes, indicative probably of the presence of larval setal sacs and possibly a rudiment of the embryonic shell. Morphology of the ventral brephic shell. previously unknown in siphonotretides, confirms earlier observations that the adult siphonotretide pedicle attachment was related entirely to the ventral mantle, and it may not be homologous with the pedicle of other lingulates. Phosphatised setae emerging from hollow spines are described for the first time in siphonotretides, most probably representing a retained primitive character. Siphonobolus priscus and Siphonobolus kalshanehensis are established as new species. (C) 2009 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.
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| 22. |
- Popov, Leonid E, et al.
(författare)
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Furongian Linguliform Brachiopods from the Alborz Mountains, Iran
- 2009
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Ingår i: Memoirs of the Association of Australasian Palaeontologists. - 0810-8889. ; 1:37, s. 103-122
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Tidskriftsartikel (refereegranskat)abstract
- Micromorphic linguliform brachiopods are described for the first time from the Furongian part of the Cambrian Mila Formation, eastern Alborz Mountains, Iran. The assemblage is dominated by acrotretides, including Dactylotreta lamellosa n. sp. and Ottenbyella hyrcanica n. sp. as well as species of the new genera Tapuritreta (T. angusta n. sp.) and Sadrocarta (S. delicatus). The siphonotretide Siphonobolus sp. also occurs in abundance, which is unusual for Furongian lingulate faunas. The newly discovered assemblage shows little similarity to contemporaneous faunas of Laurentia, Baltica and Kazakhstanian terranes, but S. delicatus is also known from the middle Furongian Series of the Malyi Karatau Range in southern Kazakhstan.
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| 23. |
- Popov, Leonid E, et al.
(författare)
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Glendonite occurrences in the Tremadocian of Baltica : first Early Palaeozoic evidence of massive ikaite precipitation at temperate latitude
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- The Tremadocian (Early Ordovician) is currently considered a time span of greenhouse conditions with tropical water surface temperature estimates, interpolated from oxygen isotopes, approaching 40 °C. In the mid-latitude Baltoscandian Basin, conodonts displaying low δ18O values, which suggest high temperatures (>40 °C) in the water column, are in contrast with the discovery of contemporaneous glendonite clusters, a pseudomorph of ikaite (CaCO3·6H2O) traditionally considered as indicator of near-freezing bottom-water conditions. The massive precipitation of this temperature sensitive mineral is associated with transgressive conditions and high organic productivity. As a result, the lower Tremadocian sediments of Baltoscandia apparently contain both "greenhouse" pelagic signals and near-freezing substrate indicators. This paradox points to other primary controlling mechanisms for ikaite precipitation in kerogenous substrates, such as carbonate alkalinity, pH and Mg/Ca ratios, as recently constrained by laboratory experiments. Preservation of "hot" conodonts embedded in kerogenous shales rich in δ18O-depleted glendonites suggests both the onset of sharp thermal stratification patterns in a semi-closed basin and the assumed influence of isotopically depleted freshwater yielded by fluvial systems.
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| 24. |
- Popov, Leonid E., et al.
(författare)
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Gondwanan faunal signatures from Early Palaeozoic terranes of Kazakhstan and Central Asia : evidence and tectonic implications
- 2009
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Ingår i: Geological Society, London, Special Publications. ; 325:1, s. 23-64
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Tidskriftsartikel (refereegranskat)abstract
- Two separate tectonic blocks in the southwestern segment of the Kazakhstanian orogen, the Chu-Ili terrane and the Karatau-Naryn terrane (with particular attention to Malyi Karatau), are selected to illustrate their geological history and major biogeographical signatures from the Cambrian to the early Silurian. Mid- to Late Ordovician brachiopod and trilobite faunas of Chu-Ili show increased endemicity of shallow shelf assemblages, whereas distinct links to equatorial ( east') peri-Gondwanan are more evident in trilobite assemblages of the outer shelf. In the Late Ordovician, strong biogeographical affinities to equatorial Gondwanan faunas became firmly established and they are also traceable into the Silurian. Early Cambrian faunas of Malyi Karatau show remarkable similarity to those of South China. From the Middle Cambrian this region evolved as an isolated carbonate seamount, but until the Early Ordovician links to South China faunas were still evident. Benthic faunas from both regions show weak links to contemporaneous faunas of Baltica and little in common with Cambrian and Ordovician faunas of the Siberian craton. This suggests their location in low southern latitudes, in relative proximity to East Gondwana, which places some constraints on plate-tectonic reconstructions in relation to the southern cluster of Kazakhstanian terranes, including Karatau-Naryn, North Tien Shan and Chu-Ili.
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| 25. |
- Popov, Leonid E., et al.
(författare)
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Himalayan Cambrian brachiopods
- 2015
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Ingår i: Papers in Palaeontology. - : Wiley. - 2056-2799 .- 2056-2802. ; 1:4, s. 345-399
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Tidskriftsartikel (refereegranskat)abstract
- A synoptic analysis of previously published material and new finds reveals that Himalayan Cambrian brachiopods can be referred to 18 genera, of which 17 are considered herein. These contain 20 taxa assigned to species, of which five are new: Eohadrotreta haydeni, Aphelotreta khemangarensis, Hadrotreta timchristiorum, Prototreta? sumnaensis and Amictocracens? brocki. Well-preserved topotype material from the classic Parahio Valley section is described for three species that have not previously been illustrated photographically. A biostratigraphical scheme based on Cambrian brachiopod occurrence is integrated with that recently proposed for trilobites. Regional correlations based on shared taxa within and across Himalayan lithotectonic belts demonstrate that erosion of Cambrian rocks in the Kurgiakh orogeny in the Parahio Valley removed little of the Parahio Formation and that all of the fossil-bearing lithotectonic zones share similar late early Cambrian brachiopods, suggesting regional faunal continuity at the time. Palaeobiogeographical analysis of the Cambrian brachiopod faunas from the Himalaya shows that they occupied a marginal position of the Australasian segment of Gondwana.
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| 26. |
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| 27. |
- Popov, Leonid E., et al.
(författare)
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Silurian (Aeronian) rhynchonelliform brachiopods of Shabdjereh, south-west Central Iran and their significance for early spiriferide evolution
- 2021
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Ingår i: Journal of Systematic Palaeontology. - : Taylor & Francis. - 1477-2019 .- 1478-0941. ; 19:3, s. 191-219
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Tidskriftsartikel (refereegranskat)abstract
- The Silurian (Aeronian) post-extinction recovery brachiopod fauna of Iran and Afghanistan is characterized by a proliferation of the Stegocornu Brachiopod Association, which includes prominent endemic rhynchonellide and spiriferide components. A local variety of that association, recently recovered from the Shabdjereh Formation of Kerman Province, East-Central Iran, contains eight brachiopod species, including the rhynchonellide Kermanirhyncha granulata gen. et sp. nov., and the spiriferides Levanispirifer alatus gen. et sp. nov. and Mictospirifer obtusus sp. nov. A new phylogenetic analysis of the earliest Late Ordovician to Aeronian spiriferides, within the general context of the Ordovician radiation of rhynchonelliform brachiopods with calcified brachial supports, reveals the following two major centres of biodiversification and dispersal: (1) the Laurentian palaeocontinent, which is the likely place of origin and initial diversification of the atrypide suborders Lissatrypidina and Anazygidina; and (2) the assemblage of Kazakh island arcs and microplates (known also as Kazakh Archipelago), which was the centre of origin and initial dispersal of the atrypid suborder Atrypidina and the order Spiriferida. South China represents a major refuge, where spiriferides survived the terminal Ordovician extinction and from where they dispersed towards adjacent parts of Gondwana including the Iranian terranes. The latter areas were an important secondary centre of spiriferide biodiversification during the Aeronian Age.
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| 28. |
- Skovsted, Christian, 1974-, et al.
(författare)
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Taxonomy, morphology, shell structure and early ontogeny of Pelmanotreta nom. nov. from the lower Cambrian of Siberia
- 2015
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Ingår i: GFF. - : Informa UK Limited. - 1103-5897 .- 2000-0863. ; 137:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- The new generic name Pelmanotreta is proposed under the provisions of the International Code of Zoological Nomenclature (ICZN) to replace Cryptotreta Pelman, 1977 (Brachiopoda), a junior homonym of Cryptotreta Blanc & Foote, 1961 (Arthropoda). This poorly known brachiopod genus and its type and only species, Pelmanotreta neguertchenensis (Pelman, 1977), from the early Cambrian of Siberia is redescribed. The family-level taxonomy of Pelmanotreta and other “cryptotretid” brachiopods is uncertain. In Pelmanotreta, dorsal valves vastly outnumber ventral valves in all collections but new specimens of the poorly known ventral valve reveal a possibly septate and poorly mineralized apical region. A prismatic hexagonal shell structure comparable to that of Salanygolina is described. P. neguertchenensis preserves the earliest known record of a larval shell in brachiopods.
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| 29. |
- Tolmacheva, Tatiana, et al.
(författare)
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Conodont biostratigraphy and faunal assemblages in radiolarian ribbon-banded cherts of the Burubaital Formation, West Balkhash Region, Kazakhstan
- 2004
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Ingår i: Geological Magazine. - 0016-7568 .- 1469-5081. ; 141:6, s. 699-715
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Tidskriftsartikel (refereegranskat)abstract
- Biostratigraphical study of the early to mid-Ordovician conodont fauna from ribbon-banded radiolarian cherts of the middle Burubaital Formation in Central Kazakhstan reveals an almost complete succession of conodont biozones from the late Tremadocian to the early Darriwilian. During this interval, biosiliceous sediments were deposited in basinal environments, inhabited by lingulate brachiopods, sponges, pterobranchs and caryocaridids in conditions of high fertility and primary productivity of surface water. The community structure of taxonomically diverse conodont assemblages typifying open oceanic environments is not significantly different from that of epicratonic basins of the North Atlantic conodont province. The regional increase of oxygenated bottom waters at the base of the Oepikodus evae Biozone is possibly related to considerable changes in palaeo-oceanographical circulation patterns. The finds of three natural clusters of Prioniodus oepiki (McTavish) enable us to propose an emended diagnosis of this species.
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| 30. |
- Zhang, Zhiliang, et al.
(författare)
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Earliest ontogeny of early Cambrian acrotretoid brachiopods : first evidence for metamorphosis and its implications
- 2018
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Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Our understanding of the ontogeny of Palaeozoic brachiopods has changed significantly during the last two decades. However, the micromorphic acrotretoids have received relatively little attention, resulting in a poor knowledge of their ontogeny, origin and earliest evolution. The uniquely well preserved early Cambrian fossil records in South China provide a great new opportunity to investigate the phylogenetically important ontogeny of the earliest acrotretoid brachiopods, and give new details of the dramatic changes in anatomy of acrotretoid brachiopods during the transition from planktotrophic larvae to filter feeding sedentary juveniles.
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| 31. |
- Zhang, Zhiliang, et al.
(författare)
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The oldest Cambrian trilobite - brachiopod association in South China
- 2021
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Ingår i: Gondwana Research. - : Elsevier. - 1342-937X .- 1878-0571. ; 89, s. 147-167
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Tidskriftsartikel (refereegranskat)abstract
- Limestones of the Xihaoping Member of the Dengying Formation in the Xiaoyangba section, South China, yield the oldest known Cambrian brachiopod-trilobite association. In this member, the trilobite Parabadiella cf. huoi co-occurs with the new brachiopod species Eoobolus incipiens sp. nov. The association provides potential for correlation of lower Cambrian successions and gives novel insights into the origin, palaeobiogeographic distribution and early evolution of linguliform brachiopods. Parabadiella occurs in shallow marine clastic and carbonate rocks in South China, demonstrating a broad distribution for this taxon. The new discovery indicates an early Chiungchussuan age (Parabadiella trilobite Zone, Cambrian Age 3) for the longstanding problematic Xihaoping Member. Furthermore, this earliest Parabadiella-Eoobolus association helps to establish close links with the oldest knowntrilobite-brachiopod assemblage from the upper Micrina etheridgei Zone (Parabadiella huoi trilobite Zone) in Australia. Eoobolus incipiens represents one of the earliest known linguliform brachiopods, with a distinctive mixture of characters shared with both problematic tommotiids, as well as paterinide, lingulide and acrotretide brachiopods, indicating that these features may be plesiomorphic for the Linguliformea. An age-constrained dispersal mode for early lingulate brachiopods is proposed, indicating that the Subphylum Linguliformea may have originated in East Gondwana and South China during Cambrian Age 3, and only subsequently dispersed to other major Cambrian palaeocontinents (e.g. Siberia, Laurentia, Antarctica, Baltica, Avalonia, West Gondwana, North China) during the late stage of the Cambrian evolutionary radiation of animals. (C) 2020 The Author(s). Published by Elsevier B.V. on behalf of International Association for Gondwana Research.
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| 32. |
- Bassett, Michael G., et al.
(författare)
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Pedicle preservation in a Silurian rhynchonelliformean brachiopod from Herefordshire, England : soft-tissue or an artefact of interpretation?
- 2008
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Ingår i: Earth and Environmental Science Transactions of the Royal Society of Edinburgh. - 1755-6910. ; 98:3-4, s. 303-308
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Tidskriftsartikel (refereegranskat)abstract
- The interpretation of pedicle soft tissue preservation in a unique brachiopodspecimen of Wenlock (Silurian) age from Herefordshire, western England, is re-assessed. Bethia serraticulma, assigned originally to the Orthida, is more probably a member of the Strophomenida (Plectambonitoidea). The supposed pedicle structure is more plausibly a weakly mineralised pedicle sheath, which is a common morphological and functional development in the early ontogeny of a number of Palaeozoic brachiopod lineages.
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| 33. |
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| 34. |
- Ebbestad, Jan Ove R., et al.
(författare)
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First occurrence of Lesueurilla prima (Gastropoda) from the Middle Ordovician (Darriwilian) of Iran
- 2016
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Ingår i: GFF. - : Informa UK Limited. - 1103-5897 .- 2000-0863. ; 138:4, s. 510-518
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Tidskriftsartikel (refereegranskat)abstract
- The near planispiral euomphaloid gastropod Lesueurilla prima (Barrande in Perner) is a typical part of the cold water Mediterranean fauna in the Lower and Middle Ordovician. It is a signature species in strata of this age in the Prague Basin in the Czech Republic, Montagne Noire in France, and Central Morocco. The species is reported for the first time from the Darriwilian of Iran where it occurs in the upper part of the Shirgesht Formation of the Derenjal Mountains north of Tabas in east Central Iran. It occurs with a small species of the bellerophontoid gastropod Sinuites sp., as well as the calymenid trilobite Neseuretinus birmanicus (Reed) and the pliomerid trilobite Ovalocephalus kanlingensis (Zhang). The biogeographic distribution of Lesueurilla suggests that the genus had its origin in cold water, high-latitude peri-Gondwana areas during the Lower Ordovician, spreading to other peri-Gondwana areas and low-latitude areas of North China, Tarim, and finally Baltica, Laurentia and Australia in the late Middle and Upper Ordovician.
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| 35. |
- Hints, Linda, et al.
(författare)
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Morphology, ontogeny and affinities of the Hirnantian triplisiid brachiopod Streptis undifera from Baltoscandia
- 2013
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Ingår i: Palaeontology. - : Wiley. - 0031-0239 .- 1475-4983. ; 56:5, s. 961-970
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Tidskriftsartikel (refereegranskat)abstract
- New silicified topotypic material of the Upper Ordovician Streptis undifera (Schmidt, 1858) from the stratotype of the Porkuni Regional Stage in Estonia provides important data on triplesiid morphology and ontogeny, which has substantial implications for our understanding of the affinity of this group of brachiopods. In particular, the new material shows that the early ontogeny of Streptis includes evidence for a cicatrix attachment and colleplax-like structure in the ventral valve. It is likely also that a lecithotrophic feeding habit evolved in triplesiidines sometime in the Ordovician, which sets them apart from all other known strophomenates. A neotype is selected among the specimens of Streptis undifera from the type locality in Porkuni. In Baltoscandia, Streptis undifera appears first in Norway in late Katian below the strata with the pentamerid brachiopod Holorhynchus. In Estonia, Streptis undifera is an index species of the early Hirnantian and occurs in association with stromatoporoid-coral reefs and related inter-reef deposits, which overly the strata with Holorhynchus. In Baltoscandia, the distribution areas of Streptis and Holorhynchus are more or less identical in spite of some differences in age.
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| 36. |
- Holmer, Lars E., 1960-, et al.
(författare)
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Brachiopod Phylogeny in the Cambrian
- 2018
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Ingår i: 8th INTERNATIONAL BRACHIOPOD CONGRESS. ; , s. 56-57
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Konferensbidrag (refereegranskat)
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| 37. |
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| 38. |
- Holmer, Lars E., et al.
(författare)
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Ordovician–Silurian Chileida—first post-Cambrian records of an enigmatic group of Brachiopoda
- 2014
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Ingår i: Journal of Paleontology. - : Cambridge University Press (CUP). - 0022-3360 .- 1937-2337. ; 88:3, s. 488-496
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Tidskriftsartikel (refereegranskat)abstract
- Brachiopods of the order Chileida have been recorded previously only from rocks of early to mid-Cambrian age (Botomian–Amgaian). They are typified by having a calcareous strophic shell with a delthyrium and colleplax, and these characters are shown to be present in species of the two new genera Tolen and Trifissura, from the Late Ordovician of Kazakhstan and the Silurian of Sweden and Britain, respectively. In specimens of Trifissura, the triangular colleplax is phosphatized secondarily by bacterial activity. It is suggested that the phosphatized colleplax represents an organic pad and that served as the original attachment structure of Trifissura by encrustation. Tolen and Trifissura represent the first post-Cambrian record of chileides from the Ordovician and Silurian; the new family Trifissuridae forms the first phylogenetic link between Cambrian chileides and Carboniferous–Permian isogrammides.
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| 39. |
- Holmer, Lars E., 1960-, et al.
(författare)
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The attachment strategies of Cambrian kutorginate brachiopods : the curious case of two pedicle openings and their phylogenetic significance
- 2018
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Ingår i: Journal of Paleontology. - : Cambridge University Press (CUP). - 0022-3360 .- 1937-2337. ; 92:1, s. 33-39
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Tidskriftsartikel (refereegranskat)abstract
- The kutorginates are commonly the most abundant rhynchonelliform brachiopod found in the early Cambrian; they are also some of the oldest known rhynchonelliforms, first appearing in the Unnamed Series 2 (Atdabanian equivalent) and becoming extinct sometime in Cambrian Series 3 (Amgaian equivalent). Moreover, kutorginates are the first known member of the rhynchonelliforms for which we have a detailed knowledge of their soft-part anatomy, including the lophophore, digestive tract, and pedicle—all exceptionally preserved in Kutorgina chengjiangensis Zhang et al., 2007 from the early Cambrian Chengjiang Lagerstätte of southern China. The stout and annulated pedicle in the original report was described as protruding between the valves; however, newly collected better-preserved material now clearly shows that the pedicle actually protrudes from the apical perforation of Kutorgina chengjiangensis. This type of apical pedicle has also been described from other early Cambrian rhynchonelliforms, including the problematic chileate Longtancunella chengjiangensis (Zhang et al., 2011a). Exceptionally preserved similar pedicles are also known to emerge apically from the Silurian chileate dictyonellid Eichwaldia subtrigonalis Billings, 1858, as well as from the recently described Silurian chileate Trifissura rigida Holmer, Popov, and Bassett, 2014. However, it is clear that the only other exceptionally preserved kutorginate—a silicified Nisusia—was provided with an adult pedicle emerging between the valves from a posterior gap; thus, Nisusia has two pedicle openings. However, the apical foramen may represent the earliest attachment of the larvae, which subsequently became nonfunctional through ontogeny. It is suggested that both types of attachment strategies may have appeared early in the stem lineage of the Rhynchonelliformea.
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| 40. |
- Holmer, Lars E., et al.
(författare)
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The enigmatic early cambrian salanygolina : a stem group of rhynchonelliform chileate brachiopods?
- 2009
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Ingår i: Palaeontology. - : Wiley. - 0031-0239 .- 1475-4983. ; 52:1, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- New material of the enigmatic brachiopod Salanygolina obliqua Ushatinskaya from the Early Cambrian of Mongolia shows that it has a colleplax- a triangular plate - in the umbonal perforation, which is enlarged by resorption. This structure is otherwise only known from the equally enigmatic Palaeozoic orders Chileida and Dictyonellida (Rhynchonelliformea, Chileata). The colleplax in Salanygolina is here considered to be homologous with that of the chileates. Salanygolina is also provided with a ridge-like pseudodeltidium, which is another chileate feature. Other characters of Salanygolina, like the radial arrangement of adductor muscle scars and postero-medially placed internal oblique muscles are characteristic of chileates, but also found in the paterinates. In contrast, mixoperipheral dorsal valves with low rudimentary interareas are well known in paterinates, but not yet recorded from chileates. Thus, Salanygolina shows a mosaic combination of morphologic characters, known both from the paterinates and chileates, indicating that it may represent a stem group of the rhynchonelliform chileate brachiopods. The laminar phosphatic secondary shell of Salanygolina is composed of closely packed and nearly identical hexagonal prisms, oriented with their long axis normal to the laminae in a honeycomb pattern. The prism walls appear to have originally been composed of organic membranes and might represent precursors of the organic sheaths of calcite fibers that are typical of calcitic shells with a fibrous microstructure.
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| 41. |
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| 42. |
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| 43. |
- Popov, Leonid E., et al.
(författare)
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A low diversity shallow water lingulide brachiopod-gastropod association from the Upper Ordovician Almaly Formation of North Kyrgyzstan
- 2007
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Ingår i: Acta Paleontologica Polonica. - 0567-7920. ; 52:1, s. 27-40
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Tidskriftsartikel (refereegranskat)abstract
- A low diversity association made up of the lingulid Tunisiglossa almalensis Popov and Mambetov, sp. nov. and the gas−tropod Ptychonema agyris Ebbestad, sp. nov. is described from the Upper Member of the Almaly Formation at KyrgyzRange, North Tien Shan, Kyrgyzstan/Kazakhstan. The specimens co−occur in dense coquinas, made up of different sizedindividuals, deposited in a shallow water, intertidal, and storm driven depositional environment. The lingulid shells dis−play a completely reduced dorsal pseudointerarea typical of Glossellinae, and the smooth shell lacking fine external gran−ulation, radial or pitted ornament, a small ventral pseudointerarea, and no dorsal median ridge place it in the hithertomonotypic Tunisiglossa known previously only from the Lower Ordovician (Tremadocian) Sanrhar Formation of Libya.It compares with Ectenoglossa sorbulakensis that is widespread in the lower to middle Caradocian Anderken Formationof Chu−Ili Range in southern Kazakhstan. Gastropods of this age have not been reported earlier in Kyrgyzstan; neither canPtychonema be compare with any taxon in the gastropod association earlier described from the contemporary AnderkenFormation in Kazakhstan. Ptychonema is otherwise commonly associated with peri−Gondwana terranes, but the Late Or−dovician dispersal pattern of the genus is unknown. Overall, however, the Upper Ordovician faunas of North Tien Shanshow close similarities to contemporaneous faunas of the Chu−Ili terrane, which have strong biogeographic signatureslinking them to the faunas of South and North China.
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| 44. |
- Popov, Leonid E., et al.
(författare)
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Ordovician (Arenig-Caradoc) Syntrophiidine brachiopods from the East Baltic Region
- 2005
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Ingår i: Palaeontology. - : Wiley. - 0031-0239 .- 1475-4983. ; 48:4, s. 739-761
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Tidskriftsartikel (refereegranskat)abstract
- Syntrophiidine brachiopods are a rare and poorly known component of Ordovician Baltoscandian faunas. They appear in the East Baltic in the Billingenian (lower Arenig) as part of the earliest known benthic assemblages dominated by elements of the Palaeozoic Evolutionary Fauna. These faunal assemblages usually include bryozoans, ostracodes, and the earliest known porambonitoids, strophomenides and endopunctate orthides, such as Idiostrophia and Orthidium, which later became characteristic of the Whiterockian brachiopod assemblages in Laurentia, but by that time had disappeared from Baltica. The superfamily Syntrophioidea reappears in Baltoscandia in the mid Caradoc. In contrast, Porambonitoidea remained the integral part of the Baltoscandian brachiopod associations through the Ordovician. Porambonites, herein redefined on the basis of restudy of the type species P. intermedius, includes only smooth porambonitoids; taxa with the distinctive ornament of radiating rows of pits first appeared in the group in the mid Arenig. The taxa Eoporambonites gen. nov., Tetralobula peregrina sp. nov., Idiostrophia prima sp. nov. and Idiostrophia tenuicostata sp. nov. are erected.
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| 45. |
- Popov, Leonid E, et al.
(författare)
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Review of the Ordovician stratigraphy and fauna of the Anarak Region in Central Iran
- 2015
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Ingår i: Acta geologica Polonica. - : Walter de Gruyter GmbH. - 0001-5709 .- 2300-1887. ; 65:4, s. 403-435
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Forskningsöversikt (refereegranskat)abstract
- The Ordovician sedimentary succession of the Pol-e Khavand area, situated on the northern margin of the Yazd block, has important differences from those in other parts of Central Iran. It has been established that the presumably terminal Cambrian to Lower Ordovician volcano-sedimentary Polekhavand Formation, exposed in the Pol-e Khavand area, has non-conformable contact with greenschists of the Doshakh Metamorphic Complex. The succeeding, mainly siliciclastic Chahgonbad Formation contains low to moderately diverse faunal assemblages, including brachiopods, cephalopods, trilobites and tentaculitids. The Darriwilian age of the lower part of the formation is well established by the co-occurrence of brachiopod genera Camerella, Phragmorthis, Tritoechia and Yangtzeella. The associated rich cephalopod fauna is different from the Darriwilian cephalopod associations of the Alborz terrane and may show some affinity with warm water faunas of North China and South Korea. It is likely that the Mid Ordovician fauna recovered from the lower part of the Chahgonbad Formation settled in the area sometime during a warming episode in the late Darriwilian. By contrast the low diversity mid Katian brachiopod association includes only three taxa, which occur together with the trilobite Vietnamia cf. teichmulleri and abundant, but poorly preserved tentaculitids questionably assigned to the genus Costatulites. This faunal association bears clear signatures linking it to the contemporaneous cold water faunas of the Arabian, Mediterranean and North African segments of Gondwana. Four brachiopod species recovered from the Chahgonbad Formation, including Hibernodonta lakhensis, Hindella prima, Lomatorthis? multilamellosa and Yangtzeella chupananica are new to science.
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| 46. |
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| 47. |
- Popov, Leonid, et al.
(författare)
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Lingulate brachiopods from the Cambrian-Ordovician boundary beds of Utah
- 2002
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Ingår i: Journal of Paleontology. - 0022-3360 .- 1937-2337. ; 76:2, s. 211-228
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Tidskriftsartikel (refereegranskat)abstract
- Seven genera and eight species of lingulate brachiopods are described from the Cambrian-Ordovician boundary beds (Cambrooistodus minutus Conodont Subzone to Rossodus manitouensis Conodont Zone) at the Lawson Cove and Lava Dam North sections, Ibex area, Utah, USA. The fauna includes one new linguloid genus, Wahwahlingula, and four new species, Lingulella? incurvata, Zhanatella utahensis, Conotreta millardensis, and Quadrisonia? lavadamensis. Lingulate brachiopods from this interval are very poorly known from Laurentia, but the recorded fauna is very similar to that described from coeval beds at Malyi Karatau, Kazakhstan, and both areas contain Eurytreta cf. bisecta (Matthew, 1901); E. sublata Popov, 1988; ZhanatellaKoneva, 1986; SchizambonWalcott, 1889; and Wahwahlingula. Eurytreta cf. bisecta is also known from the Lower Ordovician of Avalonian Canada, Britain, and Scandinavia.
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| 48. |
- Zhang, Zhifei, et al.
(författare)
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An obolellate brachiopod with soft-part preservation from the early cambrian chengjiang fauna of China
- 2011
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Ingår i: Journal of Paleontology. - : Cambridge University Press (CUP). - 0022-3360 .- 1937-2337. ; 85:3, s. 460-463
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Tidskriftsartikel (refereegranskat)abstract
- The obolellates represent a poorly understood group of the oldest known cosmopolitan calcareous rhynchonelliform brachiopods. They made their first appearance in the early Atdabanian and became extinct at the end of the Middle Cambrian. Consequently, any information concerning the soft anatomy of this ephemeral lineage of brachiopods has great phylogenetic significance. This is the first report on two specimens of an obolellate with fine preservation of soft parts including the pedicle, marginal setae and possible imprints of a spiral lophophore, recovered from the early Cambrian Chengjiang Konservat Lagerstatte of Kunming, southern China. The setae are thin and densely fringed along the shell margin. The stout pedicle is distinctly composed of densely stacked tabular bodies, lacking a central coelomic lumen; it emerges through a possible foramen, and slightly tapers posteriorly with the distal end attached to exoskeletons of other organisms.
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