scholarly journals Flume experiments reveal flows in the Burgess Shale can sample and transport organisms across substantial distances

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Orla G. Bath Enright ◽  
Nicholas J. Minter ◽  
Esther J. Sumner ◽  
M. Gabriela Mángano ◽  
Luis A. Buatois
Keyword(s):  
British Columbia ◽  
Community Structure ◽  
Experimental Results ◽  
Cambrian Explosion ◽  
Burgess Shale ◽  
Flume Experiments ◽  
Sediment Gravity Flows ◽  
Gravity Flows ◽  
First Time ◽  
Field Approaches

AbstractThe exceptionally preserved fossils entombed in the deposits of sediment-gravity flows in the Cambrian Burgess Shale of British Columbia have been fundamental for understanding the origin of major animal groups during the Cambrian explosion. More recently, they have been used to investigate the evolution of community structure; however, this assumes that the fossil assemblage represents an in-life community. Here we test this assumption for the first time based on experimental and field approaches. We use flume experiments to create analog flows and show that transport of the polychaete Alitta virens over tens of kilometers does not induce significantly more damage beyond that already experienced due to normal decay processes. Integration of experimental results with taphonomic assessment of fossils and sedimentological analysis suggests that the organisms of the Burgess Shale in the classic Walcott Quarry locality could have undergone substantial transport and may represent a conflation of more than one community.

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 .

Nectocaridid ecology, diversity, and affinity: early origin of a cephalopod-like body plan

Paleobiology ◽  
10.1666/12029 ◽  
2013 ◽  
Vol 39 (2) ◽  
pp. 297-321 ◽  
Author(s):  
Martin R. Smith
Keyword(s):  
Body Plan ◽  
Cambrian Explosion ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
Low Reynolds Number Flow ◽  
Reynolds Number Flow ◽  
Number Flow ◽  
Early Origin ◽  
First Time ◽  
Cephalopod Evolution

Nectocaridids are soft-bodied early to middle Cambrian organisms known from Burgess Shale-type deposits in Canada, China, and Australia. Originally described as unrelated species, they have recently been interpreted as a clade; their flexible tentacles, camera-type eyes, lateral fins, internal gills, axial cavity, and funnel point to a relationship with the cephalopods. However, aspects of this reinterpretation, including the relevance of the group to cephalopod evolution, have been called into question.Here, I examine new and existing nectocaridid material, including a large new form that may represent a sexual dimorph of Nectocaris pteryx. Differences between existing taxa largely represent taphonomic variation between sites and specimens—which provides further constraint on the organisms' anatomy. I revise the morphology of the tentacles and fins, and describe mouthparts and phosphatized gills for the first time. A mathematical analysis supports the presence of the earliest known camera-type eyes, and fluid mechanical considerations suggest that the funnel is optimized for efficient jet propulsion in a low Reynolds number flow regime.Nectocaridids closely resemble coleoid cephalopods, but a position deeper within Cephalopoda raises fewer stratigraphic challenges. Whether its coleoid-like construction reflects common ancestry or profound convergence, the Nectocaris body plan adds substantially to Cambrian disparity, demonstrating the rapid colonization of nektobenthic niches after the Cambrian explosion.

A new helcionelloid mollusk from the middle Cambrian Burgess Shale, Canada

2013 ◽  
Vol 87 (6) ◽  
pp. 1067-1070 ◽  
Author(s):  
Simon Conway Morris ◽  
John S. Peel
Keyword(s):  
British Columbia ◽  
New Species ◽  
Cambrian Explosion ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
Marine Life ◽  
A New Species

Burgess Shale-type faunas provide unique insights into the Cambrian “explosion”. Their degree of representativeness of Cambrian marine life in general is, however, less easy to establish. One line of evidence is to consider only the skeletal component of a Burgess Shale-type fauna and compare that with a typical Cambrian assemblage. This paper describes a new species of helcionelloid mollusk (Totoralia reticulata n. sp.) from the middle Cambrian Burgess Shale of British Columbia. Whilst much rarer than the co-occurring smooth shelled helcionelloid Scenella amii, the strongly costate morphology of Totoralia reinforces comparisons with Cambrian shelly faunas. The extension of the range of Totoralia from Argentina to Canada adds support to the proposed derivation of the Precordillera terrane of Mendoza from Laurentia.

scholarly journals A new hurdiid radiodont from the Burgess Shale evinces the exploitation of Cambrian infaunal food sources

2019 ◽  
Vol 286 (1908) ◽  
pp. 20191079 ◽  
Author(s):  
J. Moysiuk ◽  
J.-B. Caron
Keyword(s):  
British Columbia ◽  
Feeding Ecology ◽  
Food Sources ◽  
Cambrian Explosion ◽  
Feeding Apparatus ◽  
Burgess Shale ◽  
Apex Predators ◽  
Oral Cone ◽  
Fossil Material ◽  
Spinous Processes

Radiodonts, a clade of Cambro-Devonian stem group euarthropods, have classically been regarded as nektonic apex predators. However, many aspects of radiodont morphology and ecology have remained unclear because of the typically fragmentary nature of fossil material. Here, we describe a new hurdiid radiodont based on abundant and exceptionally well-preserved fossils from the Burgess Shale (Marble Canyon area, British Columbia, Canada). Cambroraster falcatus gen. et sp. nov . is characterized by an extra-large horseshoe-shaped head carapace, bearing conspicuous posterolateral spinous processes, and partially covering a short trunk with eight pairs of lateral flaps. Each of the pair of frontal appendages possess five mesially curving rake-like endites equipped with a series of anteriorly directed hooked spines, altogether surrounding the oral cone. This feeding apparatus suggests a micro to macrophagous sediment-sifting feeding ecology. Cambroraster illuminates the evolution of Hurdiidae and evinces the exploitation of the diversifying infauna by these large and specialized nektobenthic carnivores in the aftermath of the Cambrian explosion.

scholarly journals Appendicular anatomy of the artiopod Emeraldella brutoni from the middle Cambrian (Drumian) of western Utah

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7945 ◽  
Author(s):  
Rudy Lerosey-Aubril ◽  
Javier Ortega-Hernández
Keyword(s):  
British Columbia ◽  
Dorsal View ◽  
Terminal Segment ◽  
Cephalic Region ◽  
Main Body ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
Major Clade ◽  
Critical Information ◽  
First Time

The non-biomineralized artiopod Emeraldella brutoni Stein, Church & Robison, from the middle Cambrian (Drumian) Wheeler Formation in Utah represents the only confirmed occurrence of the genus Emeraldella outside of the stratigraphically older (Wuliuan) Burgess Shale Konservat-Lagerstätte in British Columbia. The hitherto known sole specimen of this species is preserved in dorsal view and lacks critical information on the ventral appendages. Here, we redescribe E. brutoni based on a new completely articulated specimen that illustrates the appendage organization in exceptional detail. The main body consists of a cephalic region covered by a semicircular head shield, a trunk including 10 tergites with expanded pleurae plus a cylindrical terminal segment, and a long articulated tailspine. The head carries a pair of elongate and flexible antennae, a pair of lateral eyes, and three pairs of post-antennal appendages. We report the presence of eyes in Emeraldella for the first time. The first post-antennal limb solely consists of an endopod with well-developed paired spiniform endites. The remaining cephalic appendages and those associated with all but the last trunk segments possess exopods terminating in paddle-shaped, distal lobes fringed with robust setae. The cylindrical terminal segment bears a pair of posteriorly oriented caudal flaps reminiscent of trunk exopods, and a styliform, possibly uniarticulate tailspine longer than the main body. The new data on E. brutoni suggests an exopodal origin for the paired caudal structures in Vicissicaudata, and improve our understanding of the fundamental organization of this major clade within Artiopoda.

Benthic foraminiferal zonation in deep-water carbonate platform margin environments, northern Little Bahama Bank

1988 ◽  
Vol 62 (01) ◽  
pp. 1-8 ◽  
Author(s):  
Ronald E. Martin
Keyword(s):  
Deep Water ◽  
Benthic Foraminifera ◽  
Carbonate Platform ◽  
Sedimentary Facies ◽  
Depositional Environments ◽  
Near Surface ◽  
Sediment Gravity Flows ◽  
Gravity Flows ◽  
Platform Margin ◽  
Water Carbonate

The utility of benthic foraminifera in bathymetric interpretation of clastic depositional environments is well established. In contrast, bathymetric distribution of benthic foraminifera in deep-water carbonate environments has been largely neglected. Approximately 260 species and morphotypes of benthic foraminifera were identified from 12 piston core tops and grab samples collected along two traverses 25 km apart across the northern windward margin of Little Bahama Bank at depths of 275-1,135 m. Certain species and operational taxonomic groups of benthic foraminifera correspond to major near-surface sedimentary facies of the windward margin of Little Bahama Bank and serve as reliable depth indicators. Globocassidulina subglobosa, Cibicides rugosus, and Cibicides wuellerstorfi are all reliable depth indicators, being most abundant at depths >1,000 m, and are found in lower slope periplatform aprons, which are primarily comprised of sediment gravity flows. Reef-dwelling peneroplids and soritids (suborder Miliolina) and rotaliines (suborder Rotaliina) are most abundant at depths <300 m, reflecting downslope bottom transport in proximity to bank-margin reefs. Small miliolines, rosalinids, and discorbids are abundant in periplatform ooze at depths <300 m and are winnowed from the carbonate platform. Increased variation in assemblage diversity below 900 m reflects mixing of shallow- and deep-water species by sediment gravity flows.

scholarly journals A reexamination of Yuknessia from the Cambrian of British Columbia and Utah

2015 ◽  
Vol 89 (1) ◽  
pp. 82-95 ◽  
Author(s):  
Steven T. LoDuca ◽  
Jean-Bernard Caron ◽  
James D. Schiffbauer ◽  
Shuhai Xiao ◽  
Anthony Kramer
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
British Columbia ◽  
National Park ◽  
Red Alga ◽  
Fine Scale ◽  
Burgess Shale ◽  
Phylogenetic Affinity ◽  
New Material ◽  
Scanning Electron

AbstractTo investigate the phylogenetic affinity of Yuknessia simplex Walcott, 1919, scanning electron microscopy was applied to the Burgess Shale (Cambrian Series 3, Stage 5) type material and to new material from the Trilobite Beds (Yoho National Park) and specimens from the Cambrian of Utah. On the basis of fine-scale details observed using this approach, including banding structure interpreted as fusellae, Yuknessia Walcott, 1919 is transferred from the algae, where it resided for nearly a century, to the extant taxon Pterobranchia (Phylum Hemichordata). Considered as such, Yuknessia specimens from the Trilobite Beds and Spence Formation (Utah) are amongst the oldest known colonial pterobranchs. Two morphs regarded herein as two different species are recognized from the Trilobite Beds based on tubarium morphology. Yuknessia simplex has slender erect tubes whereas Yuknessia stephenensis n. sp., which is also known in Utah, has more robust erect tubes. The two paratypes of Y. simplex designated by Walcott (1919) are formally removed from Yuknessia and are reinterpreted respectively as an indeterminate alga and Dalyia racemata Walcott, 1919, a putative red alga.

A new Late Silurian (Pridolian) naraoiid (Euarthropoda: Nektaspida) from the Bertie Formation of southern Ontario, Canada—delayed fallout from the Cambrian explosion

2004 ◽  
Vol 78 (6) ◽  
pp. 1138-1145 ◽  
Author(s):  
Jean-Bernard Caron ◽  
David M. Rudkin ◽  
Stuart Milliken
Keyword(s):  
Late Ordovician ◽  
Cambrian Explosion ◽  
Burgess Shale ◽  
Soft Bottom ◽  
Southern Ontario ◽  
Middle Cambrian ◽  
Holotype Specimen ◽  
Extinction Events ◽  
Lazarus Effect ◽  
Mass Extinction Events

The discovery of a new naraoiid nektaspid in the Upper Silurian (Pridolian) of southeastern Ontario significantly extends the range of this unusual group. Nektaspids are nonmineralized arthropods typical of Early and Middle Cambrian soft-bottom communities, but were thought to have become extinct in the Late Ordovician. The unique holotype specimen of Naraoia bertiensis n. sp. comes from a Konservat–Lagerstätte deposit renowned for its eurypterid fauna (the Williamsville Member of the Bertie Formation). Naraoia bertiensis lacks thoracic segments and is morphologically similar to Naraoia compacta from the Middle Cambrian Burgess Shale, save for the presence of a long ventral cephalic doublure and a subtly pointed posterior shield. To examine the phylogenetic relationships of the new naraoiid, we coded characters of the holotype specimen and of nine previously described nektaspids. The results confirm a sister taxon relationship between Naraoia compacta and Naraoia bertiensis and the monophyly of nektaspid forms lacking thoracic segments (family Naraoiidae). This latter group may have arisen from an ancestral segment-bearing form through heterochronic loss of thoracic segments early in the Cambrian. The disjunct occurrence of a naraoiid nektaspid in the Late Silurian resembles the reappearance of other “Lazarus taxa” that were thought to have been eliminated during mass extinction events. The naraoiid lineage survived the Late Ordovician biotic crisis, but in this case the “Lazarus effect” seems likely to be taphonomic in origin.

Dr. Bodington

1897 ◽  
Vol 43 (182) ◽  
pp. 675-675
Keyword(s):  
British Columbia ◽  
Marked Improvement ◽  
Common Humanity ◽  
The Government ◽  
First Time ◽  
The Way

The following cutting from The Province, published in Victoria, British Columbia, will be of interest to many of the members of our Association:—“The Provincial Secretary's ‘Bill to amend the Lunacy Act’ was introduced to the House (not before it was wanted) on Wednesday last, and read a first time. We trust that provisions have been made to render impossible any recurrence of the sad circumstances attendant upon the care of the insane which we recently had occasion to deplore, and that common humanity will compel members to take the keenest possible interest in every clause of the enactment. Reform has been the order of the day at the Westminster Asylum ever since Dr. Bodington took charge two years ago—another appointment, by the way, upon which it is only just to congratulate the Government. We predicted that Dr. Bodington would prove a success, and we are glad to hear on excellent and altogether unbiassed authority that the asylum may now be considered in every way a credit to the country. Perfect discipline is maintained amongst the patients without any necessity for that ‘restraint’ which formed so barbarous a characteristic of the ancient régime. More satisfactory still is the knowledge that marked improvement has become noticeable amongst cases formerly rated hopeless or incurable.”

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