Lower Cambrian pediculate lingulids from Yunnan, China

1993 ◽  
Vol 67 (5) ◽  
pp. 788-798 ◽  
Author(s):  
Jin Yugan ◽  
Hou Xianguang ◽  
Wang Huayu
Keyword(s):  
New York ◽  
British Columbia ◽  
Lower Cambrian ◽  
Structure And Function ◽  
The Other ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
Middle Ordovician ◽  
Early Ordovician ◽  
And Function

The vermiform pedicle is one of the most distinctive organs of modern lingulids, but it is rarely preserved. Only two fossil specimens of lingulids with pedicle casts have been reported, one from the Ordovician and the other from the Devonian. No record of fossil pedicles of Lingulella and Lingulepis, the dominant Cambrian and Early Ordovician lingulids, is known. Fossil lingulids from the Lower Cambrian of Chengjiang County, Yunnan, suggest that the structure and function of the pedicle of the lingulids has not changed significantly from its first appearance. A comparison of fossil pedicle of lingulids from the Lower Cambrian, Chengjiang County (China), the Burgess Shale, Middle Cambrian, British Columbia (Canada), the Trenton Formation, Middle Ordovician, New York (U.S.A.), and the Devonian, Devonshire (England, U.K.) shows that the delthyrial area to which the pedicle muscles are attached was reduced in length through time until these muscles were completely embraced by the two valves.Two species, Lingulella chengjiangensis n. sp. and Lingulepis malongensis Rong, are described.

scholarly journals Extraordinary fossils reveal the nature of Cambrian life: a commentary on Whittington (1975) ‘The enigmatic animal Opabinia regalis , Middle Cambrian, Burgess Shale, British Columbia’

2015 ◽  
Vol 370 (1666) ◽  
pp. 20140313 ◽  
Author(s):  
Derek E. G. Briggs
Keyword(s):  
British Columbia ◽  
Royal Society ◽  
Early Evolution ◽  
Cambrian Explosion ◽  
Burgess Shale ◽  
Critical Interval ◽  
Middle Cambrian ◽  
Early Ordovician ◽  
History Of ◽  
350Th Anniversary

Harry Whittington's 1975 monograph on Opabinia was the first to highlight how some of the Burgess Shale animals differ markedly from those that populate today's oceans. Categorized by Stephen J. Gould as a ‘weird wonder’ ( Wonderful life , 1989) Opabinia , together with other unusual Burgess Shale fossils, stimulated ongoing debates about the early evolution of the major animal groups and the nature of the Cambrian explosion. The subsequent discovery of a number of other exceptionally preserved fossil faunas of Cambrian and early Ordovician age has significantly augmented the information available on this critical interval in the history of life. Although Opabinia initially defied assignment to any group of modern animals, it is now interpreted as lying below anomalocaridids on the stem leading to the living arthropods. This commentary was written to celebrate the 350th anniversary of the journal Philosophical Transactions of the Royal Society .

Autochthonous and allochthonous rocks in the Pistolet Bay area in northernmost Newfoundland

1968 ◽  
Vol 5 (3) ◽  
pp. 501-513 ◽  
Author(s):  
M. F. Tuke
Keyword(s):  
Lower Cambrian ◽  
Volcanic Rocks ◽  
The Other ◽  
North Central ◽  
Middle Ordovician ◽  
Early Ordovician ◽  
Bay Area

Rocks outcropping in the northernmost part of the island of Newfoundland belong to two sequences, which are partly contemporaneous and very different in lithology. One sequence consists of Lower Cambrian sandstones and Lower and Middle Ordovician carbonates and shales. The other sequence consists of graywackes, volcanic rocks, and ultrabasic intrusions, which are, in part, early Ordovician. This latter sequence is interpreted as allochthonous because it is underlain by major low-angle faults and because of its strong facies contrast with the first sequence. The allochthonous rocks occur in three separate klippen.The trend of slickensides, attitude of folds, and deflection of beds at fault surfaces all indicate that movement along the low-angle faults that underlie the klippen was to the northwest. The klippen probably originated from an area 60 km to the southeast, which is on strike with similar rocks in north-central Newfoundland.It is suggested that the klippen moved by gravity sliding in late Middle Ordovician time.

The Cambrian Fauna of the Leny Limestone, Perthshire, Scotland

2007 ◽  
Vol 98 (02) ◽  
pp. 199-218 ◽  
Author(s):  
Terence P. Fletcher ◽  
Adrian W. A. Rushton
Keyword(s):  
New York ◽  
North American ◽  
Lower Cambrian ◽  
Outer Edge ◽  
Open Ocean ◽  
Middle Cambrian ◽  
Middle Ordovician ◽  
The North ◽  
Appalachian Orogen ◽  
Selection Of

ABSTRACTDark limestones in the old quarries at Leny, Perthshire contain sparse beds with tiny fossils. They are poorly preserved and, though barely affected by the Ordovician Grampian Event tectonism, there is some taphonomic distortion and many are corroded along stylolitised horizons. The fauna mainly comprises trilobites of two types, open-ocean miomerids and polymerid shelf dwellers. MiomeridsCondylopygecf.eliandKiskinella cristataindicate a stratigraphical position equivalent to the base of the paradoxidid Amgan Stage of Siberia; traditionally regarded as ‘Middle Cambrian’. However, the bulk of the Leny miomerids, notably species ofPagetides, are forms described from the outer edge of Laurentia, within theBonnia–OlenellusZone, where it is considered to be ‘Lower Cambrian’. The Leny polymerids were likely transported off-shelf and some are conspecific with taxa in the Laurentian allochthonous Quebec and New York successions of the Early–Middle Ordovician (Taconic) Appalachian Orogen. The Leny Limestone and Shale Member of the Keltie Water Grit Formation is part of the Dalradian Supergroup deposited in an off-shelf Caledonide Grampian Terrane of the Humber Tectonostratigraphical Zone, midway between the North American successions and the Greenland Caledonides.Additional to the trilobites, brachiopods, sponges, hyoliths, bradoriids and a selection of indeterminable organic fragments occur; none of which has any particular age significance.

Cambrian Lagerstätten: their distribution and significance

1985 ◽  
Vol 311 (1148) ◽  
pp. 49-65 ◽  
Keyword(s):  
British Columbia ◽  
Special Reference ◽  
Community Ecology ◽  
Lower Cambrian ◽  
South Australia ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
Upper Cambrian ◽  
Exceptional Preservation ◽  
Biotic Diversity

The geological setting, biotic diversity and taphonomy of Cambrian soft-bodied Lagerstätten are reviewed with special reference to the Lower Cambrian Emu Bay Shale (South Australia) and Kinzers Formation (Pennsylvania), and the Middle Cambrian Stephen Formation (Burgess Shale and adjacent localities, British Columbia). Brief mention is made also of a number of more minor occurrences in the U.S.A., China and Spain. Exceptional preservation in the Upper Cambrian is discussed by K. J. Müller (this symposium). These soft-bodied Lagerstätten afford a series of special insights into the nature of Cambrian life. Emphasis is laid on the information they provide with regards (i) levels of diversity and the proportion of skeletized taxa; (ii) the origin and relative success of bodyplans; (iii) community ecology and evolution.

Middle Cambrian ctenophores from the Stephen Formation, British Columbia, Canada

1996 ◽  
Vol 351 (1337) ◽  
pp. 279-308 ◽  
Keyword(s):  
British Columbia ◽  
The Other ◽  
Single Specimen ◽  
Burgess Shale ◽  
Hunsrück Slate ◽  
Middle Cambrian ◽  
Living Species ◽  
Oral Area ◽  
Aboral Pole

The Ctenophora are a marine phylum of gelatinous swimmers and crawlers, with a minimal fossilization potential. To date only two acceptable fossil specimens are known, both from the Devonian Hunsruck Slate. Here we re-describe the single specimen of Fasciculus vesanus from the Phyllopod bed of the Burgess Shale (Middle Cambrian). The globose body bore two sets of comb-rows: one elongate and estimated to total ca.16, the other shorter and totalling ca. 64, so giving a total of ca. 80. Internally there were at least two and possibly four prominent organs, each consisting of an elongate series of lobes. Xanioascus canadensis gen. nov., sp. nov. is recorded from a horizon low in the Stephen Formation, from the Glossopleura zone. It is more similar to extant ctenophores than F. vesanus , but the comb-rows total ca. 24. These converge on the aboral pole, where there is evidence for the polar fields. The comb-rows stop short of the oral area, which is poorly defined. Internally prominent ovoid bodies are sometimes present, but their significance is uncertain. Ctenorhabdotus capulus gen. nov., sp. nov. occurs in the Bathyuriscus-Elrathina zone of the Stephen Formation. It is best known from the Raymond Quarry of the Burgess Shale, but also occurs in the underlying strata, including the Phyllopod bed. The comb-rows appear to have totalled 24, and converged towards the aboral pole, adjacent to which they amalgamate as groups of three rows each. In the fossils the comb-rows then join eight strands, possibly representing the meridional canals, that meet as a ring. In addition, in each group of three comb-rows the central row appears to have been conspicuously shorter than those flanking it. The aboral pole also bore a prominent capsule, presumably housing the statocyst. The oral area, which lacks the comb-rows, bore a voluminous mouth, apparently surrounded by a folded margin with possible musculature. These Cambrian ctenophores differ from the Devonian and Recent taxa in a number of ways. They have a larger number of comb-rows and apparently an absence of tentacles. In addition, structures found in the Cambrian ctenophores, such as the lobed organs of F. vesanus and the ovoid bodies of X. canadensis lack obvious counterparts in living species. The wider affinities of the ctenophores remain mysterious, but they probably evolved very early in the metazoan radiations, perhaps from an animal with an anterio-posterior axis and a ciliated surface.

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.

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