Middle Cambrian polychaetes from the Burgess Shale of British Columbia

1979 ◽  
Vol 285 (1007) ◽  
pp. 227-274 ◽  
Keyword(s):  
Feeding Habits ◽  
Indirect Evidence ◽  
Type A ◽  
The Body ◽  
Thin Layers ◽  
Entire Body ◽  
Burgess Shale ◽  
Body Type ◽  
Type Specimens ◽  
Middle Cambrian

The Burgess Shale (Middle Cambrian) polychaetes Canadia spinosa Walcott, Burgessochaeta setigera (Walcott) gen. nov. and Peronochaeta dubia (Walcott) gen. nov. are redescribed on the basis of Walcott’s type specimens and on much additional material. Two new polychaetes Insolicorypha psygma gen. et sp. nov. and Stephenoscolex argutus gen. et sp. nov. are described. A poorly preserved specimen of unknown generic affinity is described as type A. The polychaetes are preserved as thin films that adhere to both sides of the split in the rock so that part and counterpart may be available. In C. spinosa, B. setigera and I. psygma , parts of the bodies such as the fascicles of setae are separated by thin layers of sediment that apparently seeped in during turbulent transport in turbidites or mudflows. The bodies therefore lie on two or more planes of microbedding and the factors that control exposure across a specimen are discussed. Aspects of the palaeoecology of the Burgess Shale are reviewed, including the distance the biota was transported prior to burial, the reasons for the exquisite preservation, and the effects of sedimentary compaction. C. spinosa was characterized by broad notosetae that extended across the dorsum, and large fascicles of neurosetae. Lobate branchiae were situated in the inter-ramal spaces. The prostomium bore a pair of elongate tentacles and the straight gut had an eversible unarmed proboscis. Several lines of evidence suggest that C. spinosa was an active benthonic swimmer. B. setigera was peculiar in possessing identical notosetae and neurosetae along the entire body. Long anterior tentacles, possibly of peristomial origin, may have been used in feeding. Indirect evidence indicates that B. setigera inhabited a burrow which it might have excavated with its proboscis. P. dubia may also have burrowed but it had uniramous parapodia bearing simple and acicular setae. The prostomium bore a pair of short appendages. I. psygma had extended neuropodia bearing cirri and elongate setae. The notopodia were reduced and cirri appear to have been wanting. The peculiar prostomium carried a pair of appendages. I. psygma is regarded as a pelagic polychaete. S. argutus possessed uniramous parapodia with simple stout setae. The bilobed prostomium bore at least one pair, and perhaps three pairs, of short appendages. Type A was the largest of the Burgess Shale polychaetes and had prominent setae on at least the anterior section of the body. Type A was a sediment eater but the feeding habits of the other polychaetes are uncertain. Particular attention is given to the influence of decay on the Burgess Shale polychaetes. To place the Burgess Shale polychaetes in some geological perspective other Cambrian worms, including a polychaete from the Spence Shale of Utah, are briefly redescribed and the late Precambrian (Ediacarian) worms Dickinsonia, Spriggina and Marywadea are assessed. Contrary to the findings of other workers, no convincing evidence for placing these latter worms in the polychaetes is forthcoming.

scholarly journals Waptia fieldensis Walcott, a mandibulate arthropod from the middle Cambrian Burgess Shale

2018 ◽  
Vol 5 (6) ◽  
pp. 172206 ◽  
Author(s):  
Jean Vannier ◽  
Cédric Aria ◽  
Rod S. Taylor ◽  
Jean-Bernard Caron
Keyword(s):  
Evolutionary History ◽  
The Body ◽  
Formal Description ◽  
Front Part ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
History Of ◽  
Ellipsoid Bodies ◽  
Active Swimming ◽  
Prey Items

Waptia fieldensis Walcott, 1912 is one of the iconic animals from the middle Cambrian Burgess Shale biota that had lacked a formal description since its discovery at the beginning of the twentieth century. This study, based on over 1800 specimens, finds that W. fieldensis shares general characteristics with pancrustaceans, as previous authors had suggested based mostly on its overall aspect. The cephalothorax is covered by a flexible, bivalved carapace and houses a pair of long multisegmented antennules, palp-bearing mandibles, maxillules, and four pairs of appendages with five-segmented endopods—the anterior three pairs with long and robust enditic basipods, the fourth pair with proximal annulations and lamellae. The post-cephalothorax has six pairs of lamellate and fully annulated appendages which appear to be extensively modified basipods rather than exopods. The front part of the body bears a pair of stalked eyes with the first ommatidia preserved in a Burgess Shale arthropod, and a median ‘labral’ complex flanked by lobate projections with possible affinities to hemi-ellipsoid bodies. Waptia confirms the mandibulate affinity of hymenocarines, retrieved here as part of an expanded Pancrustacea, thereby providing a novel perspective on the evolutionary history of this hyperdiverse group. We construe that Waptia was an active swimming predator of soft prey items, using its anterior appendages for food capture and manipulation, and also potentially for clinging to epibenthic substrates.

The specific status of the two cirratulid polychaetes, Dodecaceria fimbriata and D. caulleryi, compared by their morphology and methods of reproduction

1979 ◽  
Vol 57 (7) ◽  
pp. 1443-1451 ◽  
Author(s):  
Peter H. Gibson
Keyword(s):  
North Atlantic ◽  
The Body ◽  
Entire Body ◽  
Morphological Similarity ◽  
Type Specimens ◽  
Statistical Comparison ◽  
The North ◽  
The North Atlantic

Dodecaceria fimbriata and D. caulleryi occur on opposite sides of the north Atlantic. Because of their morphological similarity various authors have suggested that they may be the same species. Both reproduce by asexual fragmentation as atokes and then sexually as epitokes. The sizes of the entire body or regions of the body of three types of individual and two types of fragment produced asexually by each species were compared statistically. The numbers of one of the types of fragment were also compared. The result of this statistical comparison and the similarity in the methods of reproduction suggest that the species are the same. The type specimens for the atokes of the two species do not exist and therefore could not be compared. However, comparable specimens sampled from both sides of the Atlantic were found to be morphologically identical. On the basis of the quantitative and qualitative findings the two species are the same and therefore D. caulleryi should be called D. fimbriata.

scholarly journals A possible case of inverted lifestyle in a new bivalved arthropod from the Burgess Shale

2019 ◽  
Vol 6 (11) ◽  
pp. 191350 ◽  
Author(s):  
Alejandro Izquierdo-López ◽  
Jean-Bernard Caron
Keyword(s):  
Phylogenetic Analysis ◽  
National Park ◽  
Suspension Feeder ◽  
The Body ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
Bayesian Phylogenetic Analysis ◽  
Stem Group ◽  
Potential Case ◽  
Caudal Rami

The origin of the arthropod carapace, an enlargement of cephalic tergites, can be traced back to the Cambrian period. However, its disparity and evolution are still not fully understood. Here, we describe a new ‘bivalved’ arthropod, Fibulacaris nereidis gen. et sp. nov., based on 102 specimens from the middle Cambrian (Wuliuan Stage) Burgess Shale, Marble Canyon area in British Columbia's Kootenay National Park, Canada. The laterally compressed carapace covers most of the body. It is fused dorsally and merges anteriorly into a conspicuous postero-ventrally recurved rostrum as long as the carapace and positioned between a pair of backwards-facing pedunculate eyes. The body is homonomous, with approximately 40 weakly sclerotized segments bearing biramous legs with elongate endopods, and ends in a pair of small flap-like caudal rami. Fibulacaris nereidis is interpreted as a suspension feeder possibly swimming inverted, in a potential case of convergence with some branchiopods. A Bayesian phylogenetic analysis places it within a group closely related to the extinct Hymenocarina. Fibulacaris nereidis is unique in its carapace morphology and overall widens the ecological disparity of Cambrian arthropods and suggests that the evolution of a ‘bivalved' carapace and an upside-down lifestyle may have occurred early in stem-group crustaceans.

The arthropod Sidneyia inexpectans , Middle Cambrian, Burgess Shale, British Columbia

1981 ◽  
Vol 295 (1079) ◽  
pp. 619-653 ◽  
Keyword(s):  
British Columbia ◽  
Posterior Margin ◽  
Three Dimensional ◽  
The Body ◽  
Gut Contents ◽  
Burgess Shale ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Middle Cambrian ◽  
Abdominal Somite

Old and new specimens of Sidneyia inexpectans have been studied and are accompanied by explanatory drawings and photographs. New reconstructions of the animal are given together with a three-dimensional model. The body consisted of a cephalon with a long backwardly directed doublure, a thorax of nine articulating somites, abdomen with cylindrical exoskeleton of two or three somites and a telson. A caudal fan was formed by a pair of uropods articulating at the posterior margin of the last abdominal somite. The cephalon had stalked eyes and preoral antennae but no walking or grasping appendages. The first four somites of the thorax had paired uniramous, prehensile walking legs attached to the body by broad coxae with spiny gnathobases. The coxae were smaller on the five posterior thoracic somites and the paired appendages were biramous, each bearing a gill supported on a flap attached at its proximal end to the first podomere of the leg. The coxa-body attachment resembles that of modern merostomes and is in advance of trilobites. Evidence suggests that Sidneyia was a bottom-living, carnivorous animal eating larger and harder food than trilobites. Gut contents include ostracodes, hyolithids, small trilobites and phosphatic debris. Sidneyia is the earliest known form which could be an ancestor to merostomes, but its body plan and absence of chelicera distinguishes Sidneyia from this group. The holotype of Amiella ornata Walcott, 1911 is reinterpreted and its synonomy with S. inexpectans is confirmed.

The Middle Cambrian metazoan Wiwaxia corrugata (Matthew) from the Burgess Shale and Ogygopsis Shale, British Columbia, Canada

1985 ◽  
Vol 307 (1134) ◽  
pp. 507-582 ◽  
Keyword(s):  
Ventral Surface ◽  
The Body ◽  
Feeding Apparatus ◽  
Burgess Shale ◽  
Significant Similarity ◽  
Middle Cambrian ◽  
Stages Of Growth ◽  
Sea Bed ◽  
Juvenile Specimen ◽  
Early Metazoan

A detailed redescription of the Middle Cambrian metazoan Wiwaxia corrugata (Matthew) is given with the aid of photographs, mostly taken under ultraviolet radiation, and explanatory camera lucida drawings. Wiwaxia is known only from the Stephen Formation with four localities within the Bathyuriscus-Elrathina Zone, the celebrated Burgess Shale (Phyllopod bed) and Ogygopsis Shale and two localities that appear to expose strata relatively high in the Formation, and a new locality in the underlying Glossopleura Zone. Specimens from the Ogygopsis Shale consist almost entirely of isolated sclerites, whereas in the Phyllopod bed the species is also known from entire specimens, semi-isolated assemblages and isolated soft-parts. T he description here is based almost entirely on Phyllopod bed m aterial. Wiwaxia was originally largely covered by sclerites. On the basis of shape and arrangement five distinct zones are recognizable: dorsal, upper lateral, lower lateral, anterior and ventro-lateral. In addition, there was a row of elongate dorso-lateral spinose sclerites running along either side of the body. Each sclerite was inserted separately via a root-like structure. Growth of the animal appears to have occurred by moulting of the sclerites; one unique juvenile specimen appears to be preserved in the act of moulting. The ventral surface was apparently an area of soft tissue devoid of sclerites. Little is known of the internal anatomy, although anteriorly there was a feeding apparatus consisting of two rows of posteriorly directed teeth. Most stages of growth are known varying from presumed juveniles, which at their smallest may have lacked spines, to adults over 50 mm long. Wiwaxia appears to have been an epifaunal deposit feeder that crawled across the sea-bed, although smaller juveniles may have been infaunal. The dorso-lateral spines may have provided protection against predators and the existence of broken spines suggests the successful deterrence of attack. The affinities of Wiwaxia do not appear to lie with the polychaetous annelids. While the possibilities of convergence cannot be eliminated, there appears to be a significant similarity between Wiwaxia and molluscs that suggests a related derivation from a turbellarian ancestor. Nevertheless, Wiwaxia has a distinctive bodyplan and as such cannot be accommodated in any known phylum. While Wiwaxia is unique to the Stephen Formation isolated sclerites from Lower Cambrian rocks appear to represent earlier wiwaxiids, although these sclerites show differences in their size and composition as com pared with Wiwaxia . Wiwaxia enhances knowledge of early metazoan evolution and ecology in the Cambrian. In particular, it gives fresh insights into the origin and relative success of certain metazoan bodyplans, the origin of trace fossils, and the importance of predation in Cambrian communities.

Banffia constricta, a putative vetulicolid from the Middle Cambrian Burgess Shale

2005 ◽  
Vol 96 (2) ◽  
pp. 95-111 ◽  
Author(s):  
Jean-Bernard Caron
Keyword(s):  
Deposit Feeder ◽  
Entire Body ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
Anterior Section ◽  
New Class ◽  
Stem Group ◽  
Posterior Section

ABSTRACTAlthough Banffia constricta was first described in 1911, the affinities of this soft-bodied fossil animal have remained unclear. Banffia is redescribed here, on the basis of over 300 specimens. Banffia has a bipartite body measuring up to 10 cm in length. The entire body is axially twisted along a spiral, clockwise as seen from the front. The anterior section consists of two fused carapace-like units with a prominent crown-like structure at the anterior end surrounding the mouth. This crown-like structure is composed of three concentric circlets. A single antenniform outgrowth lies posterior to the mouth. The posterior section of Banffia is composed of 40 to 50 lightly sclerotised segments. The anus is terminal, and situated in a caudal notch. The gut is straight. Simple serially repeated structures along the gut may represent metameric mid-gut diverticulae. Banffia is considered to have been an epibenthic gregarious animal and possibly a deposit-feeder.Banffia is putatively classified as an end-member of the phylum Vetulicolia, in a new class, the Banffozoa. If the vetulicolids represent a stem-group deuterostome, the absence of gills and a possible endostyle in Banffia is problematic. The presence of mid-gut diverticulae in Banffia may represent a link with the protostomes.

The arthropod Odaraia alata Walcott, Middle Cambrian, Burgess Shale, British Columbia

1981 ◽  
Vol 291 (1056) ◽  
pp. 541-582 ◽  
Keyword(s):  
British Columbia ◽  
The Body ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
The Family

This, the first detailed description, interpretation and reconstruction of Odaraia alata , is based on all 29 known specimens. These include material of Eurysaces pielus Simonetta and Delle Cave, 1975, which is synonymized with O. alata herein. The head bore a pair of large eyes anteriorly and a paired mandible posteriorly. Features between these are poorly defined and the number of limb-bearing cephalic somites is unknown. The carapace was bivalved and essentially tubular in configuration, enclosing most of the body anteriorly. The trunk included up to at least 45 uniform short wide limb-bearing somites. The trunk appendages were biramous (with the possible exception of the first two), with an outer lamellate branch projecting dorsad of a segmented, spinose and apparently sometimes bifurcate inner branch which shows some evidence of variation along the trunk. The telson bore three large flukes, two projecting laterally and one vertically. The evidence suggests that O. alata fed by employing the carapace as a filter chamber within which the appendages, which trapped small pelagic animals, were confined. The arthropod probably swam on its back, using the appendages. Although the flukes did not articulate proximally, the telson appears to have been well adapted as a stabilizing and steering organ. O. alata shows some similarities to the Crustacea, particularly the Branchiopoda, but the preservation of the features of the cephalon is inadequate to allow its affinities to be determined unequivocally. It is classified in the family Odaraidae Simonetta and Delle Cave, 1975, but assignment to a higher taxon within the arthropods is not considered to be justified.

Occurrence of the hurdiid radiodont Cambroraster in the middle Cambrian (Wuliuan) Mantou Formation of North China

2020 ◽  
Vol 94 (5) ◽  
pp. 881-886 ◽  
Author(s):  
Zhixin Sun ◽  
Han Zeng ◽  
Fangchen Zhao
Keyword(s):  
Body Length ◽  
North China ◽  
Geographic Range ◽  
The Body ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
Spinous Processes

AbstractThe hurdiid radiodont Cambroraster is characterized by a prominent horseshoe-shaped head carapace, which bears conspicuous posterolateral spinous processes and covers half of the body length, and a pair of frontal appendages possessing rake-like endites. Here we report the discovery of characteristic central and lateral elements as well as a possible appendage endite for Cambroraster from the Cambrian Wuliuan Mantou Formation of North China. This discovery suggests that Cambroraster had dispersed over a wide biogeographic range and expands the geographic range of Hurdiidae. The increasing discoveries of exceptionally preserved fossils in the Upper Shale Member of the Mantou Formation indicate that this horizon is a promising Burgess Shale–type Lagerstätte.

scholarly journals Skimming the surface with Burgess Shale arthropod locomotion

2011 ◽  
Vol 279 (1733) ◽  
pp. 1613-1620 ◽  
Author(s):  
Nicholas J. Minter ◽  
M. Gabriela Mángano ◽  
Jean-Bernard Caron
Keyword(s):  
Direct Evidence ◽  
The Body ◽  
Sedimentation Rates ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
Ecological Information ◽  
Mode Of Life ◽  
Bottom Waters ◽  
Shale Formation ◽  
Chengjiang Biota

The first arthropod trackways are described from the Middle Cambrian Burgess Shale Formation of Canada. Trace fossils, including trackways, provide a rich source of biological and ecological information, including direct evidence of behaviour not commonly available from body fossils alone. The discovery of large arthropod trackways is unique for Burgess Shale-type deposits. Trackway dimensions and the requisite number of limbs are matched with the body plan of a tegopeltid arthropod. Tegopelte , one of the rarest Burgess Shale animals, is over twice the size of all other benthic arthropods known from this locality, and only its sister taxon, Saperion , from the Lower Cambrian Chengjiang biota of China, approaches a similar size. Biomechanical trackway analysis demonstrates that tegopeltids were capable of rapidly skimming across the seafloor and, in conjunction with the identification of gut diverticulae in Tegopelte , supports previous hypotheses on the locomotory capabilities and carnivorous mode of life of such arthropods. The trackways occur in the oldest part (Kicking Horse Shale Member) of the Burgess Shale Formation, which is also known for its scarce assemblage of soft-bodied organisms, and indicate at least intermittent oxygenated bottom waters and low sedimentation rates.

Sign in / Sign up

Export Citation Format

Share Document