Lower Cambrian halkieriids from Oxfordshire, UK

1998 ◽  
Vol 135 (4) ◽  
pp. 501-508 ◽  
Author(s):  
S. CONWAY MORRIS ◽  
D. McILROY ◽  
A. W. A. RUSHTON
Keyword(s):  
Lower Cambrian ◽  
The Other ◽  
Siberian Section ◽  
North Greenland

Lower Cambrian sediments from the Withycombe Farm borehole (Oxfordshire) yield isolated halkieriid sclerites. All bear prominent ridges, and most appear to be either cultrates or palmates, although distinction between the two in the available material is generally difficult. Two other sclerites are more elongate: one may represent a spinose sclerite, while the other is possibly derived from the siculate zone of the original scleritome. Adjacent horizons of the Withycombe Formation yield disc-like fossils, superficially similar to hyolith opercula or monoplacophorans. These are tentatively identified as deriving from the same halkieriid scleritome. Two main types are identified, and these may correspond to the anterior and posterior shells of Halkieria evangelista from the lower Cambrian Sirius Passet fauna of North Greenland. The age of the Withycombe Formation within the Cambrian is not entirely resolved, but faunal evidence suggests an equivalence to the Cuslett Formation of southeast Newfoundland, which corresponds to either the upper Tommotian or lower Atdabanian of the standard Siberian section.

Articulated halkieriids from the Lower Cambrian of North Greenland and their role in early protostome evolution

1995 ◽  
Vol 347 (1321) ◽  
pp. 305-358 ◽  
Keyword(s):  
Body Size ◽  
Molecular Biology ◽  
Lower Cambrian ◽  
Burgess Shale ◽  
Internal Anatomy ◽  
Middle Cambrian ◽  
Functional Consequence ◽  
Primitive State ◽  
North Greenland

Articulated halkieriids of Halkieria evangelista sp. nov. are described from the Sirius Passet fauna in the Lower Cambrian Buen Formation of Peary Land, North Greenland. Three zones of sclerites are recognizable: obliquely inclined rows of dorsal palmates, quincuncially inserted lateral cultrates and imbricated bundles of ventro-lateral siculates. In addition there is a prominent shell at both ends, each with radial ornamentation. Both sclerites and shells were probably calcareous, but increase in body size led to insertion of additional sclerites but marginal accretion of the shells. The ventral sole was soft and, in life, presumably muscular. Recognizable features of internal anatomy include a gut trace and possible musculature, inferred from imprints on the interior of the anterior shell. Halkieriids are closely related to the Middle Cambrian Wixaxia , best known from the Burgess Shale: this clade appears to have played an important role in early protostome evolution. From an animal fairly closely related to Wixaxia arose the polychaete annelids; the bundles of siculate sclerites prefigure the neurochaetae whereas the dorsal notochaetae derive from the palmates. Wixaxia appears to have a relic shell and a similar structure in the sternaspid polychaetes may be an evolutionary remnant. The primitive state in extant polychaetes is best expressed in groups such as chrysopetalids, aphroditaceans and amphinomids. The homology between polychaete chaetae and the mantle setae of brachiopods is one line of evidence to suggest that the latter phylum arose from a juvenile halkieriid in which the posterior shell was first in juxtaposition to the anterior and rotated beneath it to provide the bivalved condition of an ancestral brachiopod. H. evangelista sp. nov. has shells which resemble those of a brachiopod; in particular the posterior one. From predecessors of the halkieriids known as siphogonuchitids it is possible that both chitons (polyplacophorans) and conchiferan molluscs arose. The hypothesis of halkieriids and their relatives having a key role in annelid—brachiopod—mollusc evolution is in accord with some earlier proposals and recent evidence from molecular biology. It casts doubt, however, on a number of favoured concepts including the primitive annelid being oligochaetoid and a burrower, the brachiopods being deuterostomes and the coelom being an archaic feature of metazoans. Rather, the annelid coelom arose as a functional consequence of the transition from a creeping halkieriid to a polychaete with stepping parapodial locomotion.

The significance of the boundary between the Rhoscolyn and New Harbour formations on Holy Island, North Wales, to the deformation history of Anglesey

2012 ◽  
Vol 150 (3) ◽  
pp. 519-535 ◽  
Author(s):  
JACK E. TREAGUS ◽  
SUSAN H. TREAGUS ◽  
NIGEL H. WOODCOCK
Keyword(s):  
Lower Cambrian ◽  
Depositional Environment ◽  
High Strain ◽  
The Other ◽  
Deformation History ◽  
Two Phase ◽  
Phase Deformation ◽  
North Wales ◽  
History Of ◽  
Tectonic Features

AbstractThe boundary between the Rhoscolyn and New Harbour formations on Holy Island, Anglesey, has been described as a high strain zone or as a thrust. The boundary is here described at four localities, with reference to the contrasting sedimentary and deformational character of the two formations. At one of these localities, Borth Wen, sandstones and conglomerates at the top of the Rhoscolyn Formation are followed, without any break, by tuffs and then mudstones of the New Harbour Formation. It is concluded that there is clear evidence of depositional continuity across the boundary here, and that both formations subsequently shared a common two-phase deformation. The first (D1) was manifestly different in intensity and scale in the two formations, whereas the second (D2) produced very similar structures in both. The other three localities provide continuity of sedimentary and tectonic features at this boundary in a traverse along the length of Holy Island, leading us to identify two previously unrecognized major D1 folds in addition to the Rhoscolyn Anticline. At one of these localities (Holyhead), we confirm the presence of Skolithos just below the boundary, supporting radiometric evidence for a lower Cambrian or later age for the Rhoscolyn Formation. A turbidite interpretation for both the Rhoscolyn and New Harbour formations best fits the available evidence. A deep-water depositional environment is still compatible with the sporadic presence of Skolithos burrows, but less so with reported observations of hummocky and swaley cross-stratification lower down the South Stack Group.

scholarly journals Lower Cambrian trace fossils from northern Greenland

1988 ◽  
Vol 137 ◽  
pp. 43-53
Author(s):  
J Bergström ◽  
J.S Peel
Keyword(s):  
Lower Cambrian ◽  
Trace Fossils ◽  
Trace Fossil ◽  
East Greenland ◽  
North West ◽  
North Greenland

Rusophyciform and cruzianaeform trace fossils are described from Lower Cambrian siliciciastic shelf deposits in North-West and North Greenland. Cruziana cf. C. dispar Linnarsson, 1869 is reported from the Dallas Bugt Formation of Inglefield Land while a new ichnospecies, Rusophycus marginatus, occurs in the Buen Formation of Peary Land and in the equivalent Humboldt Formation of Daugaard-Jensen Land. These species show no similarity to the Cruziana sp. previously described from East Greenland. The occurrence of C. cf. C. dispar could indicate some similarity in Cambrian trace fossil 'ichnofaunas' between Greenland and Europe but available material is insufficient to ciarify this relationship.

scholarly journals Trachyplax arctica, a New Multiplated Problematic Fossil from the Lower Cambrian of North Greenland

2009 ◽  
Vol 54 (3) ◽  
pp. 513-523 ◽  
Author(s):  
Cecilia M. Larsson ◽  
John S. Peel ◽  
Anette E.S. Högström
Keyword(s):  
Lower Cambrian ◽  
North Greenland

XXVII.—Scottish National Antarctic Expedition, 1902–1904: Cambrian Organic Remains from a Dredging in the Weddell Sea

1921 ◽  
Vol 52 (4) ◽  
pp. 681-714 ◽  
Author(s):  
W. T. Gordon
Keyword(s):  
Lower Cambrian ◽  
Point Of View ◽  
Weddell Sea ◽  
The Other ◽  
Great Abundance ◽  
Wide Geographical Distribution ◽  
The Family ◽  
Antarctic Expedition ◽  
Form Part ◽  
Organic Remains

From a biological point of view considerable interest must always attend any investigation of the earliest known organisms, and, although we may legitimately infer that a flora and fauna existed prior to Cambrian times, the organisms preserved for us in rocks of that age constitute, at present, the first chapter of palæontological history. For this reason alone the Archæocyathinæ are important, since they form part of the Lower Cambrian fauna. When, however, we consider that the genera included in the group are very distinct from one another (indicating that the family was probably of considerable antiquity even in those early times), that the types have, as far as we know, a wide geographical distribution, and that to certain skeletal characters usually associated with the Porifera they unite others more common among the Cœlenterata, interest is still further stimulated. On the other hand, although recorded in great abundance from several widely separated localities, they are not, as a rule, common fossils in Cambrian strata, and consequently the group has not received much attention.

scholarly journals Lower Cambrian fossils from Nyeboe Land, North Greenland fold belt

1974 ◽  
Vol 65 ◽  
pp. 17-17
Author(s):  
J.S Peel
Keyword(s):  
Lower Cambrian ◽  
Fault System ◽  
Fold Belt ◽  
Major Strike ◽  
North Greenland

Reconnaissance mapping and collecting was carried out in the Robeson Channel area of North Greenland during 1965-66 by P. R. Dawes and J. H. Allaart as part of Operation Grant Land. Within the fold belt in Nyeboe Land a major strike fault system separates a northern unit of limestones, slates and sandstones from a less-severely deformed calcareous greywacke and shale sequence of probable Silurian age.

scholarly journals New Cambrian faunas from Peary Land, eastern North Greenland

1979 ◽  
Vol 91 ◽  
pp. 29-36
Author(s):  
A.R Palmer ◽  
J.S Peel
Keyword(s):  
Lower Cambrian ◽  
Early Cambrian ◽  
Middle Cambrian ◽  
Late Cambrian ◽  
Middle And Late Cambrian ◽  
North Greenland

Early, Middle and Late Cambrian faunas from Peary Land, eastern North Greenland, are briefly documented. The Early Cambrian faunas of the lower Brønlund Fjord Group are assigned to the Bonnia-Olenellus Zone, although olenellids from the underiying Buen Formation may be older. Strata from the upper Brønlund Fjord Group with Middle Cambrian faunas are seemingly separated from the Lower Cambrian by a discontinuity, without representation of early Middle Cambrian zones. Faunas from lower beds of the overlying Tavsens Iskappe Group span the Middle-Late Cambrian boundary. Upper beds ofthe Tavsens Iskappe Group are assigned to the Late Cambrian, but corroborative faunal evidence is not yet available.

scholarly journals Notes on the Precambrian to Lower Cambrian stratigraphy of the south-eastern part of Heilprin Land, Independence Fjord, North Greenland

1971 ◽  
Vol 35 ◽  
pp. 9-10
Author(s):  
H.F Jepsen
Keyword(s):  
Lower Cambrian ◽  
Eastern Shore ◽  
The South ◽  
South Eastern ◽  
North Greenland

As a member of the 7th Danish Peary Land Expedition in the summer of 1970 led by Count Eigil Knuth, the author had the opportunity to study a section through the Precambrian, Eocambrian and Lower Cambrian strata along the south-eastern shore of Heilprin Land (fig. 2). The main purpose was to examine the Precambrian Midsommersø dolerites (see below), and also to map the sedimentary formations of the area. This report describes the results of the mapping.

scholarly journals Slope apron and deep shelf sediments of the Brønlund Fjord and Tavsens Iskappe Groups (Lower Cambrian – Lower Ordovician), North Greenland: stratigraphy, facies and depositional setting

1994 ◽  
Vol 169 ◽  
pp. 7-24
Author(s):  
J.R Ineson ◽  
F Surlyk ◽  
A.K Higgins ◽  
J.S Peel
Keyword(s):  
Lower Cambrian ◽  
Lower Ordovician ◽  
Shelf Sediments ◽  
Depositional Setting ◽  
The Relationship ◽  
New Formation ◽  
North Greenland

The aim of this paper is to present a review of the stratigraphy and regional depositional setting of the Brønlund Fjord and Tavsens Iskappe Groups in their northern outcrop. In addition, the Kap Stanton Formation, a new formation of the Tavsens Iskappe Group, is formally defined. In particular, the aim is to clarify the relationship between these northern sections and the better known, more proximal shelf sediments of the southern outcrop belt.

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