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 “evolution” of Anomalocaris and its classification in the arthropod class Dinocarida (nov.) and order Radiodonta (nov.)

1996 ◽  
Vol 70 (2) ◽  
pp. 280-293 ◽  
Author(s):  
Desmond Collins
Keyword(s):  
British Columbia ◽  
Sea Cucumber ◽  
Great Difficulty ◽  
Burgess Shale ◽  
Middle Cambrian ◽  
The Past ◽  
History Of ◽  
The Many ◽  
Life On Earth ◽  
Mistaken Identification

The remarkable “evolution” of the reconstructions of Anomalocaris, the extraordinary predator from the 515 million year old Middle Cambrian Burgess Shale of British Columbia, reflects the dramatic changes in our interpretation of early animal life on Earth over the past 100 years. Beginning in 1892 with a claw identified as the abdomen and tail of a phyllocarid crustacean, parts of Anomalocaris have been described variously as a jellyfish, a sea-cucumber, a polychaete worm, a composite of a jellyfish and sponge, or have been attached to other arthropods as appendages. Charles D. Walcott collected complete specimens of Anomalocaris nathorsti between 1911 and 1917, and a Geological Survey of Canada party collected an almost complete specimen of Anomalocaris canadensis in 1966 or 1967, but neither species was adequately described until 1985. At that time they were interpreted by Whittington and Briggs to be representatives of “a hitherto unknown phylum.”Here, using recently collected specimens, the two species are newly reconstructed and described in the genera Anomalocaris and Laggania, and interpreted to be members of an extinct arthropod class, Dinocarida, and order Radiodonta, new to science. The long history of inaccurate reconstruction and mistaken identification of Anomalocaris and Laggania exemplifies our great difficulty in visualizing and classifying, from fossil remains, the many Cambrian animals with no apparent living descendants.

scholarly journals Interspecies variation of larval locomotion kinematics in the genus Drosophila and its relation to habitat temperature

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Yuji Matsuo ◽  
Akinao Nose ◽  
Hiroshi Kohsaka
Keyword(s):  
Bayesian Inference ◽  
Environmental Factors ◽  
Evolutionary History ◽  
Evolutionary Rate ◽  
Phylogenetic Analyses ◽  
The Body ◽  
Quantitative Relation ◽  
Individual Species ◽  
Habitat Temperature ◽  
History Of

Abstract Background Speed and trajectory of locomotion are the characteristic traits of individual species. Locomotion kinematics may have been shaped during evolution towards increased survival in the habitats of each species. Although kinematics of locomotion is thought to be influenced by habitats, the quantitative relation between the kinematics and environmental factors has not been fully revealed. Here, we performed comparative analyses of larval locomotion in 11 Drosophila species. Results We found that larval locomotion kinematics are divergent among the species. The diversity is not correlated to the body length but is correlated instead to the habitat temperature of the species. Phylogenetic analyses using Bayesian inference suggest that the evolutionary rate of the kinematics is diverse among phylogenetic tree branches. Conclusions The results of this study imply that the kinematics of larval locomotion has diverged in the evolutionary history of the genus Drosophila and evolved under the effects of the ambient temperature of habitats.

scholarly journals Interspecies variation of larval locomotion kinematics in the genus Drosophila and its relation to habitat temperature

2020 ◽  
Author(s):  
Yuji Matsuo ◽  
Akinao Nose ◽  
Hiroshi Kohsaka
Keyword(s):  
Bayesian Inference ◽  
Phylogenetic Trees ◽  
Evolutionary History ◽  
Evolutionary Rate ◽  
Phylogenetic Analyses ◽  
The Body ◽  
Quantitative Relation ◽  
Individual Species ◽  
Habitat Temperature ◽  
History Of

AbstractSpeed and trajectory of locomotion are characteristic traits of individual species. During evolution, locomotion kinematics is likely to have been tuned for survival in the habitats of each species. Although kinematics of locomotion is thought to be influenced by habitats, the quantitative relation between the kinematics and environmental factors has not been fully revealed. Here, we performed comparative analyses of larval locomotion in 11 Drosophila species. We found that larval locomotion kinematics are divergent among the species. The diversity is not correlated to the body length but is correlated instead to the minimum habitat temperature of the species. Phylogenetic analyses using Bayesian inference suggest that the evolutionary rate of the kinematics is diverse among phylogenetic trees. The results of this study imply that the kinematics of larval locomotion has diverged in the evolutionary history of the genus Drosophila and evolved under the effects of the minimum ambient temperature of habitats.

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.

Fleas on the Back of a Wild Dog

2018 ◽  
Vol 28 (1) ◽  
pp. 63-74
Author(s):  
John Conger
Keyword(s):  
Evolutionary History ◽  
Life Experience ◽  
The Body ◽  
History Of The Body ◽  
History Of ◽  
Wild Dog ◽  
The Moment ◽  
Present Life ◽  
Complete History

«Fleas on the Back of a Wild Dog” describes the evolutionary history of the body we address as somatic therapists. Competent therapists take a complete history, and this paper addresses an ignored history, disregarded, concerning the body itself. As body-oriented therapists, the historical body in front of us, like the psychological history, has often unexpected relevance. The body we walk around in is no invention of the moment. Our instinctual attitudes carry a history that deepens our sense of the body’s purposeful movements and it’s frustrations. Otherwise uninformed, we suffer a loss of background. This paper provides something of the innate skills still underlying our present life experience.

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 Divergent Evolution of Arthropod Brains

2018 ◽  
pp. 30-70 ◽  
Author(s):  
Nicholas J. Strausfeld
Keyword(s):  
Nervous System ◽  
Evolutionary History ◽  
Sedimentary Rocks ◽  
Divergent Evolution ◽  
Comparative Neuroanatomy ◽  
Middle Cambrian ◽  
Major Transitions ◽  
Horseshoe Crabs ◽  
History Of ◽  
Living Species

Occasionally, fossils recovered from lower and middle Cambrian sedimentary rocks contain the remains of nervous system. These residues reveal the symmetric arrangements of brain and ganglia that correspond to the ground patterns of brain and ventral ganglia of four major panarthropod clades existing today: Onychophora, Chelicerata, Myriapoda, and Pancrustacea. Comparative neuroanatomy of living species and studies of fossils suggest that highly conserved neuronal arrangements have been retained in these four lineages for more than a half billion years, despite some major transitions of neuronal architectures. This chapter will review recent explorations into the evolutionary history of the arthropod brain, concentrating on the subphylum Pancrustacea, which comprises hexapods and crustaceans, and on the subphylum Chelicerata, which includes horseshoe crabs, scorpions, and spiders. Studies of Pancrustacea illustrate some of the challenges in ascribing homology to centers that appear to have corresponding organization, whereas Chelicerata offers clear examples of both divergent cerebral evolution and convergence.

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 .

A new vauxiid sponge from the Kaili Biota (Cambrian Stage 5), Guizhou, South China

2017 ◽  
Vol 154 (6) ◽  
pp. 1334-1343 ◽  
Author(s):  
XINGLIAN YANG ◽  
YUANLONG ZHAO ◽  
LOREN E. BABCOCK ◽  
JIN PENG
Keyword(s):  
Geographic Distribution ◽  
South China ◽  
North American ◽  
Evolutionary History ◽  
Burgess Shale ◽  
The Family ◽  
History Of ◽  
Morphological Differences ◽  
North Greenland

AbstractThe skeleton of a new vauxiid sponge (Order Verongida), Angulosuspongia sinensis gen. et sp. nov., described on the basis of material from calcareous mudstones of the Kaili Formation (Cambrian Stage 5), Jianhe area, Guizhou, South China, is composed of two layers of fused spicules outlining hexagonal or polygonal openings. These vauxiid remains are the first reported from outside Laurentia, and represent only the second genus attributed to the family. Its age is close to but still slightly older than the Burgess Shale Biota, and it appears to be a primitive relative of other members of the Vauxiidae. The morphological differences between Chinese and Laurentian vauxiid sponges may be a result of vicariance. These specimens not only extend the geographic distribution of vauxiids, but also help to fill a chronostratigraphical gap between North Greenland and North American material and provide additional evidence for understanding the evolutionary history of the Demospongiae.

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.

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