New material of trilobites and agnostoids has been collected from in situ occurrences of the Miaolingian Exporrecta Conglomerate in V & auml;sterg & ouml;tland, Sweden, and from Pleistocene ice-rafted boulders of the Andrarum Limestone and Exporrecta Conglomerate in Denmark, which are assumed to derive from that region. Both units represent the lower part of the Lejopyge laevigata Zone. The erratic boulders of Andrarum Limestone consist of compact, light-to dark-grey, highly fossiliferous limestone, essentially identical to the Andrarum Limestone in southernmost Scandinavia (Sk & aring;ne-Bornholm). To date, no in situ occurrences of this lithology have been documented from anywhere in Scandinavia north of Sk & aring;ne. The new fossil material includes well-preserved specimens of Acontheus acutangulus, Corynexochus spinulosus and Dolichometopus svecicus. Notably, the new pygidia of these taxa show features not recorded in the respective type specimens, which are refigured here for comparison.
A rare new agnostoid species, Tomagnostella tullbergi n. sp., is described from the lower part of the middle Cambrian Lejopyge laevigata Zone in Scandinavia, corresponding to the lower part of the Guzhangian global Stage. The species is currently known only from the Andrarum Limestone Bed of Sk & aring;ne, southernmost Sweden, and coeval strata in the Oslo Region, Norway; it has also been recorded from ice-rafted Andrarum Limestone found in Germany. The material assigned to T. tullbergi n. sp. has previously been confused with Tomagnostella exsculpta. The new species is characterized by a cephalon with a moderately angular glabellar front (distinctly angular in T. exsculpta) and a pygidium with a narrow, pointed axis showing a depressed tip; a small secondary node is located within this depression close to the tip of the axis (in T. exsculpta the axis is broad and rounded posteriorly and without a posterior depression; a minute terminal node may or may not be present). Tomagnostella tullbergi n. sp. is also comparatively large-sized whereas T. exsculpta attains smaller maximum sizes.
An Early Ordovician fauna of linguliform brachiopods and euconodonts is described from the Alum Shale Formation in northernmost Vasterbotten County, northern Sweden. The fauna was recovered from a single carbonate concretion collected at an exposure near the northern shore of Lake Storvindeln. Despite of the fragmentary and tectonized preservation of the obtained fossils, at least eight different taxa of linguliform brachiopods and four species of euconodonts could be identified. Among the brachiopods, the ephippelasmatid Pomeraniotreta biernatae Bednarczyk, 1986 is most common; it is associated among others with the acrotretids Eurytreta cf. sabrinae (Callaway, 1877) and Ottenbyella sp., and a spinose specimen potentially representing the zhanatellid Thysanotos. Two of the brachiopod taxa appear to present new species, Pomeraniotreta n. sp. and Mytoella? n. sp., but additional material would be needed for a formal description. Euconodont specimens are rare and comprise coniform elements of Drepanodus arcuatus Pander, 1856, Drepanoistodus aff. amoenus (Lindstrom, 1955) sensu Lofgren (1994), Paroistodus numarcuatus (Lindstrom, 1955) and Rossodus aff. manitouensis Repetski & Ethington, 1983. Evaluation of the stratigraphic distribution of the different taxa of brachiopods and euconodonts under consideration of the local geology, suggests that the investigated sample represents a level in the upper part of the Tremadocian (Tr2) part of the Alum Shale Formation. The fauna represents the northernmost occurrence of age diagnostic Early Ordovician (Tremadocian) fossils in Sweden.
Centropleurid trilobites include five genera of which Centropleura Angelin, Anopolenus Salter, Clarella Howell and Luhops Snajdr are known from eight species in the traditional middle Cambrian (Miaolingian Series, Drumian Stage) of Sweden and Denmark (Bornholm). Beishanella Xiang & Zhang has not been recorded in Scandinavia so far, and no centropleurids have been reported from Norway. Of these taxa, only Centropleura is common in Scandinavia. Two pygidia previously identified as Centropleura sp. and Anopolenus sp. from erratics in Germany and Bornholm, respectively, as well as a new pygidum from Scania in Sweden are here identified as Anopolenus henrici Salter. Elsewhere, the species is known from Wales, Avalonian Canada, Siberia, Alaska, and Sardinia, occurring in the A. atavus and P. punctuosus zones (the former in Siberia only). The presence of this species increases the known diversity of Centropleuridae in Scandinavia and is important for correlation between Baltica and Avalonia.
Pengia Geyer & Corbacho is a Cambrian burlingiid trilobite with fused trunk segments devoid of any articulation in the anamorphic and epimorphic phases of development. The type species is Pengia fusilis (Peng etal.) from the Wanshania wanshanensis Zone of China. Here we describe a second species, Pengia palsgaardia sp. nov., from the Lejopyge laevigata Zone of the Paradoxides forchhammeri Superzone. It comes from a glacial erratic in Denmark which probably originated in the Alum Shale Formation of Vastergotland, Sweden. Pengia palsgaardia is a large burlingiid (similar to 10mm in length), with 14 fused segments in the trunk whose boundaries are marked by ridges. The axis is narrow, with the axial furrows faintly indicated or effaced across the median. Laterally along the axis and the tapering glabella, symmetrical globular lobes are developed that are pinched at their base. During ontogeny the glabellar furrows are pit-like adaxially but shallow towards the axial furrow as the globular lobes develop. Their pit-like appearance in Pengia palsgaardia and some other burlingiid species is not considered similar to the condition seen in oryctocephalid trilobites. A median preglabellar ridge resembling that of Schmalenseeia Moberg develops late in ontogeny but in early ontogeny the preglabellar field resembles that of Burlingia Walcott, Alumenella Geyer & Corbacho and Niordilobites Geyer & Corbacho. This gives Pengia a more basal position in the schmalenseeid lineage, outside the derived Schmalenseeia. In mature specimens the facial sutures in P.palsgaardia are fused, but an ocular suture may have been present. During ontogeny Pengia would have gone through the anamorphic and protomeric protaspid segmental conditions, but articulation between either the cephalon and pygidium, or pygidium and thoracic segments of the trunk never developed so it did not progress beyond the protaspid phase. This extreme protomeric development is considered to be a derived feature in Pengia.
This paper describes the morphology and discusses the taxonomy of the paradoxidid trilobites present in the moult ensemble described by Ebbestad et al. (2013) from a huge limestone concretion of the Alum Shale Formation collected at Ostnar, Jamtland. Two species, both represented by numerous but small complete holaspid specimens are described as new: Eccaparadoxides? thorslundi sp. nov. is distinctive, but its generic position is considered doubtful; Hydrocephalus spinulosus is similar to H. vikensis Rushton & Weidner, 2007 (also present as a rarity in the moult ensemble) and is partly distinguished from it by characters of the thorax. Also illustrated are a few specimens that have been collected at various localities between Hackhs and Brunflo. They appear to represent individuals of some of the species in the moult ensemble and are about twice the size of their type specimens.
Sparse material of an agnostid trilobite, previously referred to as Tomagnostus cf. corrugatus (Illing 1916), is recognized as a new species, T. brantevikensis n. sp. It occurs in the middle Cambrian (approximate to Cambrian provisional Series 3) Triplagnostus gibbus and Acidusus atavus zones (Almbackenian regional Stage) in Scania, southernmost Sweden, but is very rare. The new species resembles T. corrugatus (Illing 1916) and T. perrugatus (Gronwall 1902), but the cephalon is characterized by a tapering glabella, creating an elongate subtriangular outline, and a deltoid depression. The pygidium has an evenly rounded border, is non-spinose, and has a long axis with a non-elongate node. Both shields have a moderately wide border.
Reinvestigation of glacial erratic boulders from Jutland, Denmark, and from northern Germany, has revealed a moderately diverse fauna with the trilobites Holmiella? sp., Epichalnipsus anartanus, Epichalnipsus sp. A, Epichalnipsus sp. B, and Berabichia erratica, three species of lingulid brachiopods, one hyolith species, and trace fossils comparable to Halopoa imbricata. Comparison with faunas from the Cambrian of Scandinavia strongly suggested a biostratigraphic position equivalent to the uppermost part of the (revised) Holmia kjerulfi–‘Ornamentaspis’ linnarssoni to lowermost Comluella?–Ellipsocephalus lunatus zones sensu Nielsen & Schovsbo (2011), or the lower to middle part of the traditional ‘Ornamentaspis’ linnarssoni Zone, but probably a particular horizon and biofacies not yet discovered in Scandinavia. Considerations of glacial transport regimes and the distribution of comparable rock units, as well as a petrographical analysis of the material from the studied erratic boulders and rocks from outcrops in Sweden, indicate that the boulders were derived from the Lingulid Sandstone Member of the File Haidar Formation and the source area is situated in the vicinity of the present-day outcrops in the Halleberg–Hunneberg area, Västergötland, Sweden.
Agraulos longicephalus and Proampyx depressus (Trilobita) from (www.2dgf.dk/publikationer/bulletin). The trilobite genus Agraulos Hawle & Corda 1847 has within Scandinavia been recorded only from Bornholm, Denmark, where its representatives occur in the Middle Cambrian Paradoxides paradoxissimus Superzone of the Alum Shale Formation. Only cranidia have been found so far, representing Agraulos longicephalus (Hicks 1872) and the rare “ Agraulos ” depressus Grönwall 1902. The two species from Bornholm are redescribed and discussed based on museum collections in combination with newly collected material from Borggård, Øleå. Agraulos longicephalus occurs commonly in the lower and upper part of the Acidusus atavus Zone as well as in the Ptychagnostus punctuosus Zone. It closely resembles the coeval Agraulos ceticephalus (Barrande 1846) known from Bohemia and eastern Newfoundland. A lectotype for “ Agraulos ” depressus is designated and re-illustrated; this taxon is hesitantly assigned to Proampyx ? It is known only from the Ptychagnostus punctuosus Zone and may represent an early, atypical Proampyx or maybe a precursor that should be separated in a new genus. Emended diagnoses of Agraulos Hawle & Corda 1847 and Proampyx Frech 1897 are presented.
Species assigned to the Middle Cambrian agnostid genus Tomagnostus are briefly reviewed and a large number of Tomagnostus sibiricus found in Scania, Sweden, are described. The material derives from the Triplagnostus gibbus Zone in the Exsulans Limestone. Several morphological features support an assignment of the species to Tomagnostus: occasional scrobiculation of the cephalon, half of the cephala have an incipient frontal sulcus, pygidia have well-developed F2 furrows, well-defined transverse depression on posteroaxis and occasionally minute marginal spines or swellings. One pygidium of the biostratigraphically important Pentagnostus praecurrens and one pygidium of the rare Onymagnostus seminula are also described from the Exsulans Limestone of Brantevik, Scania. The new findings expand the stratigraphic ranges of these species in Scandinavia.
Seventeen taxa of exotic trilobites representing eight families are described from the olenid- and agnostoid-dominated strata of the uppermost Cambrian Series 3 and lower Furongian alum shale facies of Sweden and from glacial erratic boulders of Denmark. Only the taxa are assigned to species level, i.e., Maladioidella abdita (Salter, 1866), Olentella rara (Westergard, 1922), Pedinocphalus peregrinus (Henningsmoen, 1957), Ptychoparia pusilla (Westergard. 1922), and Westergaardella olenorum (Westergard, 1922), whereas the others are left under open nomenclature or remain unrecognized. Most are described for the first time from the Cambrian of Scandinavia. Their affinities point to a strong connection with East Gondwana, Laurentia, Kazakhstania and Siberia. Exotic trilobites appear in the succession directly after periods of very low oxygen concentration in the Alum Shale Sea; their occurrences correspond to the ranges of agnostoid arthropods in the succession and seem to be linked to global transgressive events causing an influx of cool mid or oxygen depleted waters onto the shelf of the Baltica palaeocontinent (Less)
The traditional Furongian trilobite biozones of Scandinavia, recently proposed abandoned due to inconsistent boundary definitions [Terfelt, F., Eriksson, M.E., Ahlberg, P. & Babcock, L.E., 2008: Furongian Series (Cambrian) biostratigraphy of Scandinavia – a revision. Norwegian Journal of Geology88, 73–87], are resurrected and elevated to superzonal rank. These superzones are usually readily recognized in the field, even by non-specialists, and for general correlation and mapping the more wide-ranging biozones are considerably more practicable than the very detailed zonation (formerly subzonation) introduced by Terfelt et al. (2008). Formal definition of the superzones is outlined including designation of stratotype sections. The superzones are each defined by the FAD of a characterizing species group and upwards delimited by the base of the succeeding superzone. The long used Olenus, Parabolina and Leptoplastus (super)zones as well as the recently introduced Acerocarina Superzone ( = Acerocare Zone of older literature) are maintained and formalized. The Protopeltura praecursor, Peltura minor and Peltura scarabaeoides zones are abandoned and replaced by two new units, named the Protopeltura and Peltura superzones, respectively. Accordingly, all Furongian superzones have a uniform naming style referring to a characteristic genus. The six Furongian superzones currently comprise 27 trilobite zones. The Paradoxides forchhammeri Superzone (Cambrian Series 3) is extended upwards to the base of the Olenus Superzone, thereby formally including the Agnostus pisiformis Zone.
A newly collected trilobite fauna from the lowermost part of the Alum Shale Formation at Øleå, Bornholm, Denmark, demonstrates the presence of a thin but richly fossiliferous Middle Cambrian Acidusus atavus Zone (Paradoxides paradoxissimus Superzone). The lower part of the zone (the Tomagnostus fissus–Ptychagnostus atavus Zone of older Scandinavian literature) is represented by a discontinuous limestone bed, up to 20 cm thick, whereas the upper part (Hypagnostus parvifrons Zone of older literature) is represented by shale, less than 80 cm thick, containing lenses of bituminous limestone. A total of 39 agnostid and 21 polymerid species are recorded from the A. atavus Zone (including 12 taxa treated under open nomenclature). One additional polymerid species collected from an ice-rafted boulder derived from the Bornholm area is also treated. The fauna is described and illustrated, with designation and reillustration of relevant lectotypes. The abundance of polymerid trilobites in comparison with nearby Scania, southern Sweden, where 25 agnostid and nine polymerid species have been reported from equivalent strata, is indicative of a less dysoxic environment in the Bornholm area, which was probably uplifted. The trilobite fauna resembles the coeval assemblages described from England, Wales, eastern Newfoundland and eastern Siberia, sharing several species not reported previously from Baltica, including Anopolenus sp., Agraulos longicephalus, Bailiella ornata, Clarella impar, Solenopleura? applanata, Acadagnostus aff. bulkurensis and Phalagnostus ovalis. A few faunal elements originally described from Bohemia and Australia are also present, viz. Hydrocephalus aff. carens, Phalagnostus nudus, Skryjagnostus pompeckji, Hypagnostus aff. clipeus, Euagnostus aff. interstrictus and Euagnostus? aff. glandifer.
New material from autochthonous and allochthonous strata in Jamtland and southern Lapland of the agnostid species Pentagnostus praecurrens (Westergard 1936) is analysed. In Scandinavian biostratigraphy, 'P. praecurrens' is the index species of the lower middle Cambrian 'Acadoparadoxides pinus - Pentagnostus praecurrens' Zone of the 'Baltoparadoxides oelandicus' Superzone. Apart from the holotype cephalon and one aberrant complete specimen, only three detached cephala and six pygidia were previously illustrated. Their association was ambiguous and five of eleven specimens were recently re-assigned to other genera. New complete specimens in the present study enable a clear assignment of cephala to pygidia. Length-width measurements combined with a multivariate analysis of cephala were used to quantify the relationship of the new material and the results are discussed. The thorax is described for the first time. More than 100 specimens allow a clear appreciation of the morphological variation of the species and comparison to populations in other regions. Occurrence in Scandinavia is restricted to the 'Acadoparadoxides pinus - Pentagnostus praecurrens' Zone of Sweden. Occurrence in the younger 'T. gibbus' Zone of Sweden is doubtful. Outside Sweden the species occurs in the 'P. praecurrens' Zone in England, Canada and Australia. In Russia, P. praecurrens has a range from the 'P. praecurrens' Zone to the 'T. gibbus' Zone and may range even into the lower part of the 'Acidusus atavus' Zone.
We describe faunas, formerly very little known, from allochthonous mid-Cambrian strata in the Fjällbränna Formation (Tåsjön Group) in Ångermanland that are equivalent to the “Paradoxides oelandicus Beds” of the autochthon. Paradoxidid trilobites are by far the commonest forms but are represented only by dissociated sclerites; 7–10 taxa appear to be present, but most of them are so incomplete that they cannot be identified with certainty. They are accompanied by rare agnostoids of two taxa, Pentagnostus praecurrens and Acadagnostus acadicus. The assemblages lack eodiscoid or other polymerid trilobites, molluscs and brachiopods, and in this respect contrast with shallower-water shelf faunas in the “Oelandicus Beds” of the Swedish autochthon, but bear comparison with shelf-edge or slope faunas from Novaya Zemlya (Arctic Russia), the Moesian Platform (Romania) and South Carolina (USA).
A mass aggregation of 148 paradoxidid trilobites and associated specimens of the agnostoid Pentagnostus praecurrens is preserved on a surface of a split orsten lens from the Middle Cambrian Series 3 Acadoparadoxides pinus-P. praecurrens Zone in Jamtland, Sweden. Most specimens are complete or nearly complete, lying parallel to the sediment surface and seem unaffected by currents or sorting. The association is interpreted as a moult ensemble. Paradoxidid specimens are represented by two taxa, identified as paradoxidid sp. 1 (n=28 specimens) and Eccaparadoxides sp. 2 (n=45 specimens). The species are preserved both dorsum up and dorsum down, in about equal number, which may reflect a natural tendency to moult in either posture. They probably moulted by opening the cephalic sutures along the wide rostrum. The dorsal sutures are invariably open and the librigenae are very often displaced, commonly backwards in relation to the cranidium, but not symmetrically in relation to the axial shield. The glabella of the paradoxidids is often crushed, so that sometimes the underlying hypostome is outlined. Very few examples show the joint between the cranidium and the trunk being broken. Facies interpretation suggests deposition below storm wave base. Rapid burial, possibly by blanketing from hypopycnal flows followed by an extended period of slow sediment input (Type 1 facies of Brett et al. 2012) may explain the unusual preservation. The animals may have lived in an ex-aerobic environment, but evidence to support this is at the moment insubstantial.
The traditional Furongian biozones of Scandinavia, based on olenid trilobites, are proposed elevated to superzonal rank. For the time being they are treated informally, except that the designation Acerocarina Superzone is proposed as replacement name for the uppermost superzone, formerly referred to as the Acerocare Zone. It comprises four zones. The lowest of these zones, hitherto referred to as the Peltura transiens Zone, is renamed as the Acerocarina granulata Zone. The distribution of the Acerocarina Superzone in Baltoscandia is mapped. A newly discovered 1.4 m thick succession on Kinnekulle, Vastergotland, yielded Parabolina heres heres, P. transiens, Peltura costata, Peltura scarabaeoides westergaardi and Sphaerophthalmus alatus. In addition, A. granulata, Pelturina punctifera and Leptoplastides? sp. were collected from loose boulders deriving from the same interval. This is the first unambiguous record of P. costata and P. punctifera in Sweden. The fossil assemblage, assigned to the P. costata Zone, contains species hitherto considered characteristic of five different biozones, viz. the Ctenopyge tumida Zone, the Parabolina lobata Zone, the P. transiens Zone, the P. costata Zone and the Westergaardia scanica Zone. P. transiens, P. scarabaeoides westergaardi and S. alatus are assumed to have been reworked, whereas P. punctifera appears one zone earlier than in Norway. Parabolina (Parabolina) heres lata, not found during this study, may turn up in the P. costata Zone or even earlier. The Acerocarina Superzone is resting on the P. lobata Zone, and the intervening zone, characterized by Peltura paradoxa (uppermost Peltura scarabaeoides superzone), is missing in the succession on Kinnekulle.
Eine paradoxidid-agnostoid Fauna aus dem Mittelkambrium (Stage 5) des kaledonischen Unteren Allochthon vom Tasjoberget, Angermanland