| 1. |
- Castellani, Christopher, et al.
(författare)
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First record of Cyanobacteria in Cambrian Orsten deposits of Sweden
- 2018
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Ingår i: Palaeontology. - : Wiley. - 0031-0239. ; 61:6, s. 855-880
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Tidskriftsartikel (refereegranskat)abstract
- The Swedish Cambrian ‘Orsten’-type fossil sites have yielded diverse secondarily phosphatized three-dimensionally preserved microfossils, mainly of arthropod affinities. Similar material has also been recorded from Canada, the UK, Poland, Siberia, China and Australia. Only one other non-arthropod group, the Cycloneuralia, is commonly reported from any of these sites, leading to the general assumption that ‘Orsten’-type preservation is largely restricted to animals with a chitin-containing cuticle. We describe here secondarily phosphatized, originally unmineralized, thread-shaped fossils etched out of Cambrian ‘Orsten’-type deposits from the Agnostus pisiformis Biozone of the Alum Shale Formation in Sweden. These fossils strikingly resemble specimens previously described from Precambrian deposits, with at least two different morphotaxa identified (Siphonophycus kestron Schopf and Oscillatoriopsis longa Timofeev & Hermann) as well as the modern Oscillatoria. This leads us to interpret the new fossils as unbranched, uniseriate filamentous cyanobacteria. Our morphological investigations, combined with morphometrics, allow grouping the specimens assigned to O. longa into two size classes, suggesting an even higher diversity within the ‘Orsten’ assemblages. The lack of cyanobacterial material in any sample younger than the A. pisiformis Biozone indicates that rather drastic changes occurred in the environment, that is, substrate conditions on the Alum Shale seafloor. This coincided with a significant change in the composition of the trilobite communities and onset of the globally recognized Steptoean Positive Isotope Carbon Excursion (SPICE) in Scandinavia.
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| 2. |
- Chen, Junyuan, et al.
(författare)
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Early Cambrian Yangtze Plate Maotianshan Shale macrofauna biodiversity and the evolution of predation
- 2007
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Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182 .- 1872-616X. ; 254:1-2, s. 250-272
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Forskningsöversikt (refereegranskat)abstract
- The large number of soft-part preserved fossils from the Lower Cambrian Maotianshan Shale (Chengjiang) Lagerstätten suggests particularly favourable conditions for a rich life on the shelf-zone sea bottom of the Yangtze Plate, China. This high degree of biodiversity opens an excellent window into the early radiation phase of Metazoa and represents a significant data source for the study of adaptive strategies among early animals. Feeding and locomotion are the main life strategies of organisms we investigated with regard to two major benthic macrofaunal components of the Maotianshan Shale biota, the nemathelminths and the arthropods. Our attempt was to test whether food, feeding and locomotory strategies of the benthic Lower Cambrian shallow-water communities were as diversified as it appears from the morphological diversity of the organisms present. Two major types of feeders can be discerned: suspension/micro-particle feeders – mostly epibenthic sedentary taxa – and larger-particle feeders, living in benthic to bentho-pelagic realms. Scant evidence exists for exclusive vegetarians, fungi eaters, biomat utilizers and for in-faunal vertical burrowers or grazers (bioturbators). Predation, in a wider sense, seems to be a, if not the, major feeding mode among metazoans. Nemathelminths and arthropods are amongst the best examples. In the benthic shallow-water regime, as exposed by the Maotianshan Shale biota, animals and their ontogenetic stages were the most suitable and readily available food source. At least for arthropods, we propose that improvement of predatory strategies was paralleled by the enhancement of locomotory and food manipulation structures. Accumulating evidence of late Precambrian to Early Cambrian metazoans exposing diverse morphologies and life styles indicates that, on the large scale, phylogenesis progressed gradually in the Late Precambrian. This renders an “explosive” radiation of Metazoa unlikely.
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| 3. |
- Eriksson, Mats, et al.
(författare)
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Baring it all- undressing Cambrian ´Orsten´phosphatocopine arthropods using synchrotron X-ray tomographic microscopy
- 2016
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Ingår i: Lethaia. - : Scandinavian University Press / Universitetsforlaget AS. - 0024-1164. ; 49:3, s. 312-326
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Tidskriftsartikel (refereegranskat)abstract
- Synchrotron radiation X-ray tomographic microscopy (SRXTM) was used to virtually dissect and peel the shields off of the microscopic, bivalved phosphatocopine crustaceans in the Cambrian ‘Orsten’ type of preservation of Sweden. Doing so opened up for an array of concealed internal structures to be observed in a fully enclosed specimen of Hesslandona ventrospinata and a semi-enclosed specimen of Hesslandona angustata. For comparison, also a head-larva stage specimen of H. angustata, with shields in ‘butterfly position’, was analysed. The X-ray tomographic data sets revealed excellently preserved structures, such as labrum, sternum, antennae, mandibular and post-mandibular limbs with their minute setae, all of which were more or less dis-guised by the enclosing shields. This, moreover, allowed assignment to growth stages of the specimens, which is impossible based solely on external morphology and size.Microspherules observed inside the shields of the semi-enclosed H. angustata specimen may represent remains of food particles, and the feeding biology of phosphatocopines is discussed in detail. Our analyses suggest that phosphatocopines were particle feeders. The SRXTM technique offers the ability to three-dimensionally reconstruct the morphology in high resolution, construct virtual serial sections and study concealed structures. The resulting data allow for new structures to be revealed for previously known taxa and for new taxa to be identified, with the added benefit of not destroying the specimens in the process. Hence, we do not longer have to rely on serendipitous finds of broken and/or open phosphatocopine specimens to elucidate their diagnostic ventral morphology.
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| 4. |
- Eriksson, Mats E., et al.
(författare)
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Half-a-billion-year-old microscopic treasures-the Cambrian 'Orsten' fossils of Sweden
- 2016
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Ingår i: Geology Today. - : Wiley. - 0266-6979. ; 32:3, s. 115-120
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The creatures that gaze back at us through the binocular microscope are so uniquely well-preserved and life-like that had we not known better we would have thought that they were modern. Instead they are half-a-billion-year-old arthropods extracted from Cambrian rocks of Sweden. The microscopic fossils, colloquially known as the 'Orsten' fossils, are now world-famous and basking in the light of the research catwalk since their discovery in the 1970s. These fossils have provided significant insight into the long lost Cambrian biotas and early animal evolution.
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| 5. |
- Liu, Teng, et al.
(författare)
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Soft- tissue anatomy of an orsten- type phosphatocopid crustacean from the cambrian furongian of China revealed by synchrotron radiation x-ray tomographic microscopy
- 2019
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Ingår i: Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen. - : Schweizerbart. - 0077-7749. ; 294:3, s. 263-274
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Tidskriftsartikel (refereegranskat)abstract
- Fossils of Orsten- type preservation represented by Skara and Phosphatocopida have been reported from the Cambrian Furongian of Western Hunan, China. Their taxonomy and external morphology are well known, but their internal soft- tissue anatomy has not been revealed yet. With the application of synchrotron radiation X-ray tomographic microscopy, here we describe the internal soft- tissue anatomy of an Orsten- type preserved phosphatocopid crustacean assigned to Hesslandona angustata. The internal organs and tissues of this specimen were collapsed after death to form a visceral mass situated within the labrum and underneath the sternal cuticle. The visceral mass contains the digestive system, including digestive tract and possible digestive glands. The digestive tract starts from the mouth, followed by oesophagus (foregut) and midgut, whereas the hind gut and anus are unknown due to incomplete preservation. Two bilaterally symmetric knob- like structures beside the midgut may be digestive glands (midgut diverticula). The visceral mass also contains other structures that may be related to nerve tissues and/or muscles, but identification as specific organs or tissues is uncertain.
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| 6. |
- Maas, Andreas, et al.
(författare)
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The ‘Orsten’—More than a Cambrian Konservat-Lagerstätte
- 2006
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Ingår i: Palaeoworld. - 1871-174X .- 1875-5887. ; 15, s. 266-282
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- In several areas of southern Sweden, limestone nodules, locally called Orsten occur within bituminous alum shales. Theseshales and nodules were deposited under dysoxic conditions at the bottom of what was most likely a shallow sea during the lateMiddle to Upper Cambrian (ca. 500 million years ago). Subsequently, the name ‘Orsten’ has been referred to particular, mainlyarthropod, fossils from such nodules, and, in a wider sense, to the specific type of preservation of minute fossil through secondarilyphosphatization. This preservation is exceptional in yielding uncompacted and diagenetically undeformed three-dimensional fossils.‘Orsten’-type preservation resulted from incrustation of a thin external layer and also by impregnation by calcium phosphate and,therefore, mineralization of the surface of the former animals during early diagenesis. Primarily, this type of preservation seems tohave affected only cuticle-bearing metazoans such as cycloneuralian nemathelminths and arthropods. ‘Orsten’ preservation in thissense seems to be limited by size, in having yielded no partial or complete animals larger than 2 mm. On the other end of the scale,even larvae 100
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| 7. |
- Olempska, Ewa, et al.
(författare)
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Exceptionally well-preserved Orsten-type phosphatocopid crustaceans from the Cambrian of Poland
- 2019
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Ingår i: Acta Palaeontologica Polonica. - : Polska Akademia Nauk Instytut Paleobiologii (Institute of Paleobiology, Polish Academy of Sciences). - 0567-7920. ; 64:1, s. 19-39
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Tidskriftsartikel (refereegranskat)abstract
- Phosphatocopids are a group of small extinct marine crustaceans, which occur widespread in Cambrian dysoxic benthic lithofacies. Whereas the anatomy of the earliest ontogenetic stages of phosphatocopids, from the head larva with four pairs of appendages onward, is well documented, that of more advanced or adult growth stages has remained almost unknown (except for the external shields). Here we describe a three-dimensionally preserved specimen of a late growth stage of Cyclotron angelini from the Furongian strata (~490 Ma) of northern Poland, which possesses six pairs of appendages (2nd–7th pairs; antennula missing), much of setation, sternum with paragnath humps, and the trunk end with the putative anus. Based on comparisons with known phosphatocopids, the cephalic feeding system of this late larva comprises the antennae with their gnathobase-like median structures on their syncoxa and the mandible with a likewise strong but oblique gnathic coxal endite. Both appendages have a short, specialized endopod bearing a prominent, dentate, stout median spine on its proximal portion. The antennulae are missing but, as in other phosphatocopids, they are not expected to have contributed to the feeding and locomotory system like they do in crustacean stem-lineage representatives and the Eucrustacea, especially in the early larval phase. The lack of an antennal exopod and strong reduction in size of the mandibular exopod of C. angelini suggest that these appendages had lost their function as locomotory and sweeping devices, in contrast to other phosphatocopids (and eucrustaceans). Therefore, they may have served mainly for food gathering in the vicinity of the mouth, which may represent an autapomorphy of this phosphatocopid species. Furthermore, in this developmental stage of C. angelini the production of water currents and movement of food particles toward the median food path was likely achieved by the large, paddle-shaped setiferous exopods of the serially developed post-mandibular limbs. For comparisons, we studied additional phosphatocopid specimens from the Dębki 2 borehole belonging to other taxa and representing different ontogenetic stages. This is also the first report of exceptionally preserved cuticular apodemes in phosphatocopids, extending internally and still bearing partly preserved, putative muscle bundles. As known from extant eucrustaceans, these apodemes most likely served as attachment sites for appendage muscles.
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| 8. |
- Olempska, Ewa, et al.
(författare)
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Phosphatic bromalites and microfossils from the Furongian (Cambrian) of northern Poland (Baltica) and palaeobiological implications
- 2023
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Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182. ; 610
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Forskningsöversikt (refereegranskat)abstract
- The Furongian Słowińska Formation in Poland yielded minute three-dimensionally preserved, phosphatic fossils. Based on shape and structure, two distinct types are identified. The first type comprises sinuously folded, coiled, or spiral string-shaped specimens, interpreted as faecal material, coprolites. The specimens measure between less than one and two mm, the strings being long and against their subcircular to circular cross-section (60–150 μm). Many strings are folded in few to more than 30 regular loops, in this exceptional complexity unknown from any comparable fossil or extant faeces. Fully stretched, such strings may have an estimated length of more than three cm, suggesting continuous production of such faeces and resistance very a longer period after defecation until fossilization. Modelling similar strings indicates that the loops were produced by sidewards swinging of the body end of the producer during forward move. EDS analysis of the strings revealed low silica content, but high amounts of phosphate pointing to a organic-rich muddy bottom, which the producers swallowed and eventually became phosphatized as faeces. The producers of this faeces might have been few millimeter long and benthic, not infaunal worms, yet, none of the putative coprolites can be unquestionably ascribed to a particular animal group. The second type of fossils comprises between 100 and 220 μm long ellipsoidal to spherical forms with a smooth but wrinkled surface. They are interpreted as collapsed and deformed eggs or embryos lacking the egg shell, rather than coprolites made of digested and squeezed remains of possibly phosphatocopid crustaceans, the most abundant component of the Polish and Baltoscandian Orsten-type fossil assemblages. The spheres also have a smooth surface, which in all cases is partly broken off, uncovering an internal mass. This ranges from a small hump of possibly embryonic material in a large void, to a completely round body possibly presenting a late shield-bearing embryo filling the entire space underneath the egg shell. We interpret this second type of fossils as the first evidence of eggs in Orsten-type preservation, most likely belonging to phosphatocopid crustaceans.
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| 9. |
- Shao, Tiequan, et al.
(författare)
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Diversity of cnidarians and cycloneuralians in the Fortunian (early Cambrian) Kuanchuanpu Formation at Zhangjiagou, South China
- 2018
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Ingår i: Journal of Paleontology. - : Cambridge University Press (CUP). - 0022-3360 .- 1937-2337. ; 92:2, s. 115-129
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Tidskriftsartikel (refereegranskat)abstract
- The latest discovery of microfossils from the lower Cambrian (Fortunian Stage) Zhangjiagou Lagerstätte in South China are presented. This lagerstätte is rich in exceptionally preserved microfossils, including embryos of Olivooides multisulcatus, Olivooides mirabilis, and Pseudooides prima; hatched stages of O. multisulcatus, O. mirabilis, Hexaconularia sichuanensis, and Quadrapyrgites quadratacris; and cycloneuralians represented by Eopriapulites sphinx. The largest known fragment of O. mirabilis implies that its adult length can be more than 9.0 mm with at least 50 annuli, and the longest known specimen of Q. quadratacris has at least 18 annuli. These unusually large specimens refute the non-feeding larvae hypothesis for Olivooides and Quadrapyrgites. Based on the current material, it is inferred that (1) early cnidarians have a high diversity in the Fortunian Stage; (2) P. prima might represent the embryonic stages of H. sichuanensis; (3) adults of Olivooides and Quadrapyrgites may have reached centimeter-scale dimensions with more than 50 annuli; (4) Olivooides and Quadrapyrgites may be better interpreted as coronate scyphozoans; (5) cycloneuralians also had a high diversity in the Zhangjiagou Lagerstätte; and (6) cycloneuralians might have originally been part of the early Cambrian meiofauna rather than belonging to the macrobenthos. Such ancestral cycloneuralians might have been Eopriapulites-like, possessing pentaradially symmetric, backward pointing, and internally hollow introvert scalids used as locomotory devices.
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| 10. |
- Stein, Martin, 1976-
(författare)
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Evolution and taxonomy of Cambrian arthropods from Greenland and Sweden
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Arthropods have a rich fossil record spanning the Phanerozoic. Biomineralized forms such as the extinct trilobites are particularly common and are proven index fossils for biostratigraphy. Forms with an unmineralized cuticle are more rare, preserved only in so called konservat lagerstätten. Cambrian strata of Greenland have yielded rich trilobite faunas with potential for intercontinental correlation of Cambrian strata, but also an exceptionally preserved fauna, the Sirius Passet Lagerstätte. The first part of this thesis is concerned with trilobite biotratigraphy of the provisional Cambrian Series 2 in Greenland. The second part is concerned with exceptionally preserved arthropods from the Sirius Passet Lagerstätte, but also from 'Orsten' deposits from the Cambrian of Sweden. Perissopyge phenax occurs in the Henson Gletscher and Paralleldal formations spanning the Series 2 and 3 boundary interval in North Greenland. It also occurs in the Sekwi Formation of Yukon Territory, demonstrating that the species may hold potential for correlation within Laurentia. An indeterminate species of Perissopyge is shown to occur in the Ella Island Formation of North-East Greenland together with Olenellus cf. hanseni, which is similar to Olenellus cf. truemani described from the Henson Gletscher Formation. If this correlation is further corroborated it would offer a first tie-point for the An t'Sron Formation of North-West Scotland which yields Fritzolenellus lapworthi, herein reported for the first time from the Bastion Formation which underlies the Ella Island Formation. Oelandocaris oelandica from ‘Orsten’ deposits in the Cambrian series 3 and 4 boundary interval in Sweden is an early representative of the Crustacean stem lineage. Kiisortoqia avannaarsuensis is a new arthropod from the Sirius Passet Lagerstätte with robust antennulae strikingly similar to the 'raptorial' limb of the problematic anomalocaridids. The ventral morphology of the 'bivalved' Isoxys volucris is described for the first time and compared with other species assigned to Isoxys from Cambrian lagerstätten around the world. Finally, Siriocaris trolla, is a new arthropod that similarities with trilobites and certain ‘trilobitomorphs’ but seems to lack important synapomorphies of these taxa, though this may be due to preservational limitations in the material at hand.
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