Upper Cambrian Of Sweden Research Articles

Cambrian bivalved arthropods

This monograph is part of a series of publications by the two authors and their collaborators (Williams et al. 1994; Hou et al. 1996; Melnikova et al. 1997; Williams & Siveter, in press) aiming toward a comprehensive inventory of an important component of the Palaeozoic arthropod fauna: the bradoriids and the phosphatocopids. These two groups of small bivalved arthropods occur worldwide from the early Cambrian to the early Ordovician. From the time of their discovery in the late 19th century, these fossils were referred to the ostracod crustaceans until their soft parts were discovered in the Upper Cambrian of Sweden (phosphatocopids of the orsten faunal assemblage; Muller 1979, 1982), the Middle Cambrian of Australia (Walossek et al. 1993), the Lower Cambrian of Great Britain (a phosphatocopid baby, Hinz 1983), and the early Cambrian of China (Chengjiang fauna; Hou et al. 1996 for the braSeilacher, A. 1992: Vendobionta and Psammocorallia: lost constructions of Precambrian evolution. Journal of the Geological Society, London 149,607413. Seilacher, A. 1994: Early multicellular life: Late Proterozoic fossils and the Cambrian explosion. In Bengtson, S. (ed.): Early Life On Earth Nobel Symposium No. 84, 389400. Columbia University Press, New York, N.Y. Valentine, J.W. 1992: Dickinsonia as a polypoid organism. Paleobiology

Trilobites and faunal dynamics in the upper Cambrian of Sweden

Trilobites and faunal dynamics in the upper Cambrian of Sweden

The Upper Cambrian bradoriid ostracod Cyclotron lapworthi is a hesslandonid

AbstractCyclotron lapworthi (Groom, 1902), one of the few British Cambrian bradoriid ostracod species known from a large number of specimens, is redescribed. It has an interdorsum, thus indicating a hesslandonid affinity. The ontogeny of C. lapworthi does not demonstrate a clear distinction of its individual moult stages but does show marked changes in the development of nodes and lobes. C. lapworthi shows wide variation in carapace shape possibly indicating that its valves were thin and relatively flexible. In England and Canada C. lapworthi is restricted to the Upper Cambrian Olenus Zone. C. lapworthi may also occur coevally in the Upper Cambrian of Sweden.

Origin of euconodont elements

Primitive euconodont elements from the Upper Cambrian of Sweden are investigated histologically and compared with co-occurring elements of paraconodonts. The proposed close relationship between the two groups is confirmed. Typical euconodont and paraconodont elements are bridged by intermediate forms. The ontogenetic development of the early euconodont elements shows striking similarities to the evolutionary development from paraconodonts to euconodonts, suggesting that evolution generally followed a peramorphic pattern (“recapitulation”). The conodont crown originated through extension of the growth lamellae around the whole element, accompanied by stronger mineralization. The first denticulation inProconodontusarose when a jagged posterior edge in juvenile specimens was enhanced by the subsequent deposition of growth lamellae, a process comparable to the regeneration of broken tips. The most primitive euconodont elements probably erupted from the epithelium earlier in ontogeny than in more advanced forms. After the appearance of the phosphatic crown, conodont elements underwent a very rapid morphological differentiation.Cordylodusmay have arisen fromProconodontus serratus.

Morphology, ontogeny, and life habit of Agnostus Pisiformis from the upper Cambrian of Sweden by K. J. Müller and D. Walossek, 1987. Fossils and Strata, No. 19. No. of pages: 124. Price: US$30.00 (softback). ISSN 0300‐9491, ISBN 82‐00‐07511‐7

Geological JournalVolume 25, Issue 2 p. 207-208 Book ReviewFree Access Morphology, ontogeny, and life habit of Agnostus Pisiformis from the upper Cambrian of Sweden by K. J. Müller and D. Walossek, 1987. Fossils and Strata, No. 19. No. of pages: 124. Price: US$30.00 (softback). ISSN 0300-9491, ISBN 82-00-07511-7 M. Romano, M. RomanoSearch for more papers by this author M. Romano, M. RomanoSearch for more papers by this author First published: April/June 1990 https://doi.org/10.1002/gj.3350250214AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume25, Issue2April/June 1990Pages 207-208 RelatedInformation

Cuticular structure of the agnostine trilobiteHomagnostus obesus

Study of the exoskeletal surface microstructure of specimens of Homagnostus obesus (Belt, 1867) from the Upper Cambrian of Sweden has given information about the structure of agnostine cuticle. It is likely that the very thin cuticle of agnostines (5-15 μm), unlike that of polymerid trilobites, was constructed only of a prismatic layer. The exoskeletons were strengthened by reticulation on the external surface, the ridges forming up to 15% of the total cuticle thickness. Pits on the visceral surface of the exoskeleton of H. obesus may have contained photoreceptors as their morphology is similar to that of the Nileus glabellar ‘tubercle’. This would have allowed the animal to monitor changes in light intensity. Possible sensory receptors in other agnostine trilobites are reviewed. Most sense organs were positioned on the unmineralized ventral surface of the organism. □Trilobita, Agnostina, exoskeleton. cuticle, micro-structure, sensory receptors.

Arthropod larvae from the Upper Cambrian of Sweden

ABSTRACTFour tiny obvious larvae unassignable to larger “Orsten” arthropods are described and reconstructed. Two of them have a naupliar appearance and may belong to crustaceans, whereas the other two represent as yet unknown types of euarthropodan larvae.

Crustacea with preserved soft parts from the Upper Cambrian of Sweden

Six monotypic new genera of small crustaceans with phosphatised integument are described from Upper Cambrian, mainly bituminous limestone of southern Sweden. These are Dala peilertae, Bredocaris admirabilis, Walossekia quinquespinosa, Rehbachiella kinnekullensis, Skara anulata and Oelandocaris oelandica. The well-preserved details reveal a nauplius-like organisation of the head region. At least in Bredocaris, Walossekia, and Rehbachiella the head tagma has only three to four specialised pairs of appendages; Skara and Oelandocaris have five pairs of headal limbs. The antennae and the mandibulae served for locomotion and for mastication. All species have a filter apparatus with a distinct filter groove and serially constructed appendages. Four of the six forms had developed a conspicuous median compound eye. Specialisation in the development of the limbs, etc., suggests that some of the forms were benthie, while others may have been epibcnthic and active swimmers, Crustacea, Dala, Bredocaris, Walossekia, Rehbachiella, Skara, Oelandocaris, soft-part preservation, Upper Cambrian, Sweden.

Weichteile von Fossilien aus dem Erdaltertum

Phosphatisation of small, soft-bodied fossils in the Upper Cambrian of Sweden yielded rich faunal assemblages, mainly of arthropods, which have been isolated from the rock by etching techniques. The highly diverse fossils are uncompressed and constitute the best preserved material known from the Paleozoic era, exposing minute details such as fine bristles, pores of glands, and eyes. Agnostus clearly has biramous appendages and therefore, cannot be regarded as trilobite anymore. The Crustacea are the most widespread components of the phosphatised fauna. The representatives of a separate order of Ostracoda already have been studied in some detail. Other primordial crustaceans include nauplius stages and show a surprising diversity in specialisation. A similar occurrence in Upper Devonian from the Carnic Alps demonstrates that this mode of preservation is not restricted to a single environment, but also can be expected elsewhere.

Phosphatocopine ostracodes with preserved appendages from the Upper Cambrian of Sweden

Mulkr. Klaus 1. 1979 01 IS: Phosphatocopine ostracodes with preserved appendages from the Upper Cambrian of Sweden. Lethaia. Vol. 12. pp. 1–27. Oslo. ISSN 0024–1164. More than 400 specimens of phosphatocopine ostracodes. representing different moult stages of Vestrogothia. Falites and Hesslandona have been recovered, with body and appendage structures preserved in minute detail. from anthraconites in the Upper Cambrian of Sweden and drift boulders deriving from that area. The secondary phosphatization of these structures, leading to preservation. is extensively discussed. It comprises even the inner lamella, but the abdomen is not preserved. Hypostome and lower lip are well developed. The large antennula is composed of a basipodite with probably two podomeres and a long exopodite with up to 18 podomeres bearing long spines, forming a natatory organ, and a broad endopodite of two to three podomeres. The biramous organization of the antennula is a unique, most primitive feature of phylogenetic significance. The antennae and up lo four additional pairs of appendages are also biramous and similar to the antennulae, not yet differentiated for specialized functions. Only the last pair is uniramous, but a second branch may have developed in subsequent moult stages not represented in the material. The movement of food into the mouth was achieved by the endites of antennulae and antennae, a function transferred backwards to other appendages during the course of ostracode phylogeny and reflected in ontogenetic trends among Recent ostracodes. The phosphatocopines were nectobenthic, filtering plankton feeders.

Notes on two new trilobites from the Upper Cambrian of Sweden

Notes on two new trilobites from the Upper Cambrian of Sweden