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Trilobite faunal dynamics on the Devonian continental shelves of the Ardenne Massif and Boulonnais (France, Belgium)

100%

Bignon A., Cronier C.

Acta Palaeontologica Polonica

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2015

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tom 60

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nr 4

During the Devonian the sedimentation on the continental shelves of Ardenne Massif and Boulonnais has changed from a mixed siliciclastic-carbonate ramp (Eifelian), through a carbonate barrier reef (Givetian) and then to a detritic influx with local mud-mounds (Frasnian). Here we analysed the faunistic dynamics of the trilobite associations through the changing environment. We used multivariate analyses (clustering and ordering) to discriminate the trilobite associations within 67 different samples. Three previously known communities and one new were recognised: the Eifelian Mixed association, the Givetian Dechenella association and the two Frasnian Bradocryphaeus and Scutellum-Goldius associations. These trilobite faunas present a progressive ecological specialisation. The Mixed association occurs both in the ramp or carbonated (local reef developed on the ramp) facies without any significant difference in its composition. The Dechenella fauna occurs preferentially close to barrier reefs, but can also survive during short periods of detrital input. The two Frasnian communities show a strong relationship with their environment. The Scutellum-Goldius association is only found in reef systems, whereas the Bradocryphaeus flourishes exclusively in lateral facies.

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Phosphatised olenid trilobites and associated fauna from the Upper Cambrian of Vastergotland, Sweden

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Ahlberg P., Szaniawski H., Clarkson E. N. K., Bengtson S.

Acta Palaeontologica Polonica

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2005

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tom 50

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nr 3

Secondarily phosphatised olenid trilobites from organic−rich limestones (orsten) in the Furongian (Upper Cambrian) of Västergötland, south−central Sweden, are described and illustrated. All trilobites originate from the Peltura scarabaeoides Zone and were collected on the western slope of Kinnekulle. Only the dorsal exoskeletons have become secondarily phosphatised, and the ventral appendages are not preserved. Yet the material is otherwise remarkably well preserved and reveals the morphology of the olenid trilobites in greater detail than hitherto known. Species belonging to the genera Ctenopyge, Sphaerophthalmus, Parabolina, and Peltura are identified, and several juvenile specimens are present in the material. The material is disarticulated and fragmentary, and it has only been possible to identify a few specimens to species level. In addition to chaetognaths and conodonts, the trilobites are associated with pelmatozoan columnals, a possible camaroid, and fossils of uncertain affinities. These fossils, along with a probable conulariid fragment from the Peltura minor Zone, are also described and discussed. The presence of a benthic fauna of pelmatozoans, and possible conulariids and camaroids, indicates that at least parts of the Peltura zones were deposited during dysoxic rather than anoxic periods. Moreover, the sea floor must have been firm enough to allow colonisation by sessile organisms.

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Upper Cambrian trilobite biostratigraphy and taphonomy at Kakeled on Kinnekulle, Vastergotland, Sweden

100%

Terfelt F.

Acta Palaeontologica Polonica

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2003

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tom 48

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nr 3

A section through the Upper Cambrian black shales and limestones at Kakeled on Kinnekulle, Västergötland, Sweden, extends from the lower–middle part of the Agnostus pisiformis Zone into the Peltura scarabaeoides Zone. Fossils are usually preserved only in the stinkstones, but in the A. pisiformis Zone trilobites can be found also in the shales. Lithologically, the stinkstones can be subdivided into primary coquinoid limestone, which include the majority of the fossils, and early diagenetically formed limestone. The orientation of cephala and pygidia of A. pisiformis were measured on four shale surfaces and one stinkstone surface. The majority of the shields were deposited with the convex side up and showed a preferred orientation, suggesting that their positions were affected by currents. Above the A. pisiformis Zone the section comprises the Olenus/Homagnostus obesus Zone (0.30 m), the upper part of the Parabolina spinulosa Zone (0.05 m), the Peltura minor Zone (1.15 m), and the Peltura scarabaeoides Zone (2.50 m). The Leptoplastus and Protopeltura praecursor zones are missing. The Olenus/H. obesus Zone is represented only by the O. gibbosus and O. wahlenbergi subzones, whereas the O. truncatus, O. attenuatus, O. dentatus, and O. scanicus subzones are missing.

4

Systematic relationships of the blind phacopine trilobite Trimerocephalus, with a new species from Causses-et-Veyran, Montagne Noire

100%

Cronier C.

Acta Palaeontologica Polonica

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2003

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tom 48

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nr 1

The paper describes a new species of blind trilobite from the lower Fammenian of Concours−le−Haut at Causses−et−Veyran, Montagne Noire (France). Trimerocephalus (Trifoliops) nigritus subgen. et sp. nov. is assigned to a new subgenus together with Tr. (Trif.) trifolius (Osmólska, 1958). This grouping is supported by the results of phylogenetic analysis of thirteen species attributed to the Fammenian genus Trimerocephalus McCoy, 1849; of 16 previously known species attributed to this genus, only 12 were represented by data of quality sufficient to be included in the analysis, using 23 morphological characters. The Frasnian phacopine Acuticryphops acuticeps (Kayser, 1889) is used as the outgroup. The three most parsimonious trees have a length of 51 steps and a consistency index of 0.82. The new subgenus Trifoliops forms a clade together with Trimerocephalus? steinachensis (Richter and Richter, 1926), supported by an exclusive synapomorphy: widening of the cephalic antero−lateral border. Tr.? steinachensis seems to be more closely related to Tr. (Trif.) trifolius (sharing two synapomorphies) and may represent a more derived taxon (possibly deserving a separate subgeneric status). The remanig Trimerocephalus species are not formally assigned to subgeneric taxa, pending further studies (their relationships are shown in cladograms). The results do not confirm the classification suggested by Chlupač (1966) for Trimerocephalus.

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Trilobites from the latest Frasnian Kellwasser crisis in North Africa [Mrirt, Central Moroccan Meseta]

100%

Feist R.

Acta Palaeontologica Polonica

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2002

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tom 47

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nr 2

Latest Frasnian trilobites are recorded for the first time from North Africa. They occur in oxygenated limestones between the Lower and Upper Kellwasser horizons at Bou Ounabdou near Mrirt, central Moroccan Meseta. The faunas are very close to the contemporaneous associations in European sections both by their taxonomic composition and by patterns of evolutionary behavior towards eye reduction. Two new taxa are described: Gondwanaspis mrirtensis gen. et sp. nov., which is the last known representative of the Odontopleuridae before its extinction at the base of the Upper Kellwasser horizon, and Pteroparia ziegleri maroccanica subsp. nov., a geographical variant of the nominal subspecies from Sessacker in the Rhenish Slate Mountains.

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A new Cambrian catillicephalid trilobite from the Shallow Bay Formation of western Newfoundland, Canada

80%

Westrop S. R., Dengler A. A.

Acta Palaeontologica Polonica

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2022

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tom 67

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nr 1

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New genus of dimeropygid trilobites from the earliest Ordovician of Laurentia

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Adrain J. M., Westrop S. R.

Acta Palaeontologica Polonica

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2006

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tom 51

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nr 3

The new genus Tulepyge includes a type species, T. tulensis nov., from the Barn Canyon Member of the House Formation, western Utah, USA, and T. paucituberculata from the Broom Point Member of the Green Point Formation, western Newfoundland, Canada. Both species are earliest Ordovician in age, with occurrence immediately above the Cambrian–Ordovician boundary. Together with the hystricurid taxon Millardicurus, the new genus is likely to serve as an indicator fossil for the Cambrian–Ordovician boundary in Laurentia, as it is already known from different biofacies on opposite margins of the continent. Tulepyge is not closely comparable with contemporaneous taxa assigned to Hystricuridae but in its dorsally convex and coarsely tuberculate exoskeleton it resembles taxa which have been referred to Dimeropygidae, most of which are considerably younger in age.

8

Red Devonian trilobites with green eyes from Morocco and the silicification of the trilobite exoskeleton

80%

Klug C., Schulz H., De Baets K.

Acta Palaeontologica Polonica

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2009

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tom 54

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nr 1

117-123

Latest Emsian (Early Devonian) sediments at the famous mud−moundand trilobite−locality Hamar Laghdad (Tafilalt, Morocco) yielded some red−coloured remains of phacopid trilobites. Closer examination revealed that the eyes of these phacopids are often greenish in colour. EDX−analyses showed that the lenses retained their original calcitic composition, possibly greenish due to Feand Mn−impurities, while most of the exoskeleton was silicified. The silicified parts contain elevated concentrations of iron which causes the red colour. This phenomenon is explained by the porosity of the exoskeleton in contrast to the homogeneous and massive construction of the lenses and their Mg−content. These incompletely silicified trilobites enabled a reconstruction of the silicification process in trilobites. Their diagenetic alteration probably occurred as a result of events associated with the Cretaceous transgression.

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First report on the occurrence of Neseuretinus and Ovalocephalus trilobites in the Middle Ordovician of Iran

80%

Ghobadi P. M., Popov L. E.

Acta Palaeontologica Polonica

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2009

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tom 54

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nr 1

125-133

In the Derenjal Mountains of east Central Iran, the upper part of the Shirgesht Formation (uppermost Darriwilian) contains a distinct trilobite assemblage that includes Neseuretinus birmanicus and Ovalocephalus aff. obsoletus among others. Both genera were previously unknown in Iran. The occurrence of Ovalocephalus represents the earliest sign of westward taxon migration from China towards higher latitudes along the West Gondwanan margin, which may be related to global warming, after a short episode of cooler climate in the early to mid Darriwilian. Patterns of biogeographical distribution of Ovalocephalus and Neseuretinussuggest that Central Iran was part of an “overlap zone” where tropical and high latitude benthic taxa mingled.

10

A new, morphologically diverse Permian trilobite fauna from Oman

80%

Fortey R. A., Heward A. P.

Acta Palaeontologica Polonica

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2015

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tom 60

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nr 1

A newly discovered trilobite fauna from the early to middle Permian Qarari Unit of northeastern Sultanate of Oman is described. It comprises exceptionally complete and well-preserved examples of five proetoid species, belonging to genera typical of an eastern Tethyan region extending through southern Asia to Timor. The shallow shelf fauna compares closely with one of Artinskian age from Afghanistan. Permian species previously assigned to Paladin are here considered unrelated to this predominantly Carboniferous clade, and are placed in a new ditomopygine genus, Simulopaladin, type species Simulopaladin tridentifer sp. nov. Three other ditomopygine species are described: Hentigia ornata sp. nov., Iranaspidion elephas sp. nov., and Acanthophillipsia felicitae sp. nov. The proetid Triproetus bonbon sp. nov. is the most complete material known of a more widespread genus.

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Revision of the late Ordovician trilobite Holotrachelus punctillosus [Tornquist, 1884] from Dalarna, Sweden

80%

Suzuki Y.

Acta Palaeontologica Polonica

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2001

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tom 46

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nr 3

Holotrachelus punctillosus from the Boda Limestone (Ashgill, Upper Ordovician) of Sweden is redescribed. The systematic position of this problematic species is discussed. Its distinctive morphology appears to be the result of an adaptation towards illaenid life habits. The pygidial morphology, with the extra-fulcral field developed as segmental pleural spines, makes an assignment possible to only four Ordovician groups, namely the Remopleuridioidea, Odontopleuroidea, Lichoidea and Cheiruroidea. Of these, the former three are so different that a direct affiliation is out of the question. Similarities with the Cheiruroidea are the more persuasive, particularly after a misinterpretation of the facial suture is corrected and some other problems are sorted out. It is suggested that the Holotrachelinae are placed within the Cheiruridae, where it may have special affinities to the Sphaerexochinae.

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Ontogeny of a new cyrtosymboline trilobite from the Famennian of Morocco

80%

Loresey-Aubril R., Feist R.

Acta Palaeontologica Polonica

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2005

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tom 50

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nr 3

Abundant trilobite remains were recovered from late mid−Famennian marlstones from various sites in Eastern Tafilalet, southeast Morocco. All belong to a single taxon previously identified as Cyrtosymbole (Waribole) prima. This taxon is designated the type species of Osmolskabole gen. nov. A redefinition of this species, including the description of newly discovered, disarticulated exuviae both in limestone and silicified state of preservation, is given. In particular, silicified sclerites of various sizes allow the first complete growth series of a cyrtosymboline proetid to be presented. The close morphological resemblance of its protaspid stages to known proetoid larvae emphasizes the homogeneity of the early ontogeny in this superfamily. The Famennian proetoid anaprotaspis is also of comparable size to that of other Devonian proetoid larvae. However, their size−range is much less than that observed in Carboniferous larvae. This suggests that the survival of proetoid trilobites at the Frasnian−Famennian Kellwasser crisis did not result from a modification of the developmental strategy, as it might have been the case at the terminal Devonian extinction event. Moreover, O. prima possesses a plectrum from the metaprotaspid to the mid meraspid periods. This implies that the natant hypostomal condition is not steadily acquired early in the ontogeny of the Proetida. Thus we preclude the use of this character in the diagnosis of this order.

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The type species of Cyrtosymbole and the oldest [Famennian] cyrtosymboline trilobites

80%

Feist R., Lerosey-Aubril R.

Acta Palaeontologica Polonica

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2005

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tom 50

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nr 3

The hitherto poorly known type species of Cyrtosymbole, i.e., Dechenella escoti, is redescribed on the basis of an abundant new material recovered from the early Famennian Lower Griotte Limestone Formation at La Tourière, near Cabrières, southern France. It includes sclerites (hypostome, librigenae, thoracic segments and external surface of the pygidium) that previously were either unknown, or represented by poorly preserved and incomplete specimens, together with a full suite of post−protaspid growth stages. The latter has revealed that certain characters, in particular the preglabellar region and postocular facial sutures, show marked changes between the early and late holaspid stages. In the past, some species have been based on immature specimens; for example the lectotype of C. escoti is an early holaspis, and the characters that it displays have been regarded as diagnostic of the genus. For confident specific assignments in cyrtosymboline trilobites it is important, therefore, to have to hand sufficient material, including late holaspids. A revised diagnosis of Cyrtosymbole is given, and only those species that share diagnostic adult characters with C. escoti are assigned to it. Insights into early growth development exemplified by C. escoti and allies corroborate the attribution of the Cyrtosymbolinae to the Proetidae.

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Enrolment in a Middle Ordovician agnostoid trilobite

80%

Bruton D. L., Nakrem H. A.

Acta Palaeontologica Polonica

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2005

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tom 50

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nr 3

Study of silicified material of Trinodus elspethi, from the Edinburg Formation, Virginia, USA, shows there is no gliding of distal parts of segments but an articulating furrow and opposing flange with prongs, acting as apodemes for muscle attachment, allowed cephalon and thorax to move as a single unit. Articulation between thorax and pygidium was more rigid with prongs from the thorax articulating in sockets on the pygidium. Support is given to the view that agnostoids lived partially enrolled with cephalon and pygidium gaping. They are unique in lacking an articulating half−ring between cephalon and thorax and the hinge joint is modified medially to provide an opening for what is interpreted as an exhalatory organ through which water passed during feeding and swimming. Peculiarities of the thorax are connected with the presence of only two thoracic segments articulating as a unit with distal tips directed anteriorly rather than posteriorly. Otherwise articulating half rings are present in the rest of the thorax and pygidium and lack of articulating facets is not unique. It is concluded that agnostoids can be shown to be trilobites.

Ograniczanie wyników

Trilobite faunal dynamics on the Devonian continental shelves of the Ardenne Massif and Boulonnais (France, Belgium)

Phosphatised olenid trilobites and associated fauna from the Upper Cambrian of Vastergotland, Sweden

Upper Cambrian trilobite biostratigraphy and taphonomy at Kakeled on Kinnekulle, Vastergotland, Sweden

Systematic relationships of the blind phacopine trilobite Trimerocephalus, with a new species from Causses-et-Veyran, Montagne Noire

Trilobites from the latest Frasnian Kellwasser crisis in North Africa [Mrirt, Central Moroccan Meseta]

A new Cambrian catillicephalid trilobite from the Shallow Bay Formation of western Newfoundland, Canada

New genus of dimeropygid trilobites from the earliest Ordovician of Laurentia

Red Devonian trilobites with green eyes from Morocco and the silicification of the trilobite exoskeleton

First report on the occurrence of Neseuretinus and Ovalocephalus trilobites in the Middle Ordovician of Iran

A new, morphologically diverse Permian trilobite fauna from Oman

Revision of the late Ordovician trilobite Holotrachelus punctillosus [Tornquist, 1884] from Dalarna, Sweden

Ontogeny of a new cyrtosymboline trilobite from the Famennian of Morocco

The type species of Cyrtosymbole and the oldest [Famennian] cyrtosymboline trilobites

Enrolment in a Middle Ordovician agnostoid trilobite