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Conway Morris, Simon, and John S. Peel. "A new helcionelloid mollusk from the middle Cambrian Burgess Shale, Canada." Journal of Paleontology 87, no. 6 (November 2013): 1067–70. http://dx.doi.org/10.1666/13-050.
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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.
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DALEY, ALLISON C., and GRAHAM E. BUDD. "New anomalocaridid appendages from the Burgess Shale, Canada." Palaeontology 53, no. 4 (July 19, 2010): 721–38. http://dx.doi.org/10.1111/j.1475-4983.2010.00955.x.
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Sprinkle, James, and Desmond Collins. "New eocrinoids from the Burgess Shale, southern British Columbia, Canada, and the Spence Shale, northern Utah, USA." Canadian Journal of Earth Sciences 43, no. 3 (March 1, 2006): 303–22. http://dx.doi.org/10.1139/e05-107.
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The family Lyracystidae n.fam. and genus Lyracystis n.gen. are proposed for the holotype and one paratype of the Middle Cambrian eocrinoid Gogia? radiata Sprinkle, the Burgess Shale "Arms" from the same unit, and many additional partial and more complete specimens of this eocrinoid collected from the Burgess Shale since 1975. A second species, Lyracystis reesei n.gen. and n.sp. is described from a single partly complete specimen from the similar-aged Spence Shale of northern Utah. Lyracystis has three wide V-shaped arms bearing numerous long straight brachioles in the notch, a partly organized theca having larger and smaller ridged plates with epispires, and a very long multiplated stalk made up of rounded or spiny small plates. Lyracystis is the longest-stalked, suspension-feeding echinoderm known from the Middle Cambrian. The three remaining paratypes of Gogia? radiata and four new specimens with possible branched brachioles from the Burgess Shale are renamed Gogia stephenensis n.sp.
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Petrie, Meredith Blair, Jane A. Gilotti, William C. McClelland, Cees Van Staal, and Sierra J. Isard. "Geologic Setting of Eclogite-facies Assemblages in the St. Cyr Klippe, Yukon–Tanana Terrane, Yukon, Canada." Geoscience Canada 42, no. 3 (July 29, 2015): 327. http://dx.doi.org/10.12789/geocanj.2015.42.073.
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The St. Cyr area near Quiet Lake hosts well preserved to variably retrogressed eclogite found as sub-metre to hundreds of metre-long lenses within quartzofeldspathic schist in south-central Yukon, Canada. The St. Cyr klippe consists of structurally imbricated, polydeformed and polymetamorphosed units of continental arc crust and ultramafic–mafic rocks. Eclogite-bearing quartzofeldspathic schist forms thrust slices in a 30 km long by 6 km wide, northwest-striking outcrop belt. The schist unit comprises metasedimentary and felsic intrusive rocks that are intercalated on the metre to tens of metres scale. Ultramafic rocks, serpentinite and associated greenschist-facies metagabbro form imbricated tectonic slices within the eclogite-bearing quartzofeldspathic unit, which led to a previously held hypothesis that eclogite was exhumed within a tectonic mélange. The presence of phengite and Permian zircon crystallized under eclogite-facies metamorphic conditions in the quartzofeldspathic host rocks indicate that the eclogite was metamorphosed in situ together with the schist as a coherent unit that was part of the continental arc crust of the Yukon–Tanana terrane, rather than a mélange associated with the subduction of oceanic crust of the Slide Mountain terrane. Petrological, geochemical, geochronological and structural similarities link St. Cyr eclogite to other high-pressure localities within Yukon, indicating the high-pressure assemblages form a larger lithotectonic unit within the Yukon–Tanana terrane.RÉSUMÉLa région de St-Cyr renferme des éclogites bien conservées à légèrement rétrogradées qui se présentent sous forme de lentilles allant de la fraction de mètre à quelques centaines de mètres de longueur, au sein d’un schiste quartzofeldspathique du centre-sud du Yukon au Canada. La klippe de St-Cyr est structurellement constituée d’unités imbriquées, polydéformées et polymétamorphisées de croûte d’arc continental et de roches ultramafiques à mafiques. Les schistes quartzofeldspathiques à lentilles d’éclogites forment des écailles de chevauchement d’une bande de 30 km de longueur par 6 km de largeur de direction nord-ouest. Les schistes sont constitués de roches métasédimentaires et de roches intrusives felsiques intercalées à des intervalles qui vont du mètre à quelques dizaines de mètres. Les roches ultramafiques, serpentinites et métagabbros au facies à schiste vert forment des écailles tectoniques imbriquées au sein de l’unité quartzofeldspathique à lentilles d’éclogite, d’où une précédente hypothèse voulant que les éclogites soient un produit d’exhumation à partir d’un mélange tectonique. La présence de phengite et de zircon permien cristallisé sous conditions métamorphiques du faciès à éclogite au sein de la roche hôte quartzofeldspathique indiquent que l’éclogite a été métamorphisée en place, avec le schiste comme unité cohérente du terrane de croûte d’arc continental de Yukon–Tanana, plutôt qu’un mélange associé à une subduction de croûte océanique du terrane de Slide Mountain. Des similarités pétrologiques, géochimiques, géochronologiques et structurales lient les éclogites de St-Cyr à d’autres lieux de hautes pressions au Yukon, ce qui indique que les assemblages de hautes pressions forment une unité lithotectonique plus grande au sein du terrane de Yukon–Tanana.
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Ausich, William I., and Loren E. Babcock. "Phylogenetic Affinities of Echmatocrinus Brachiatus (Middle Cambrian Burgess Shale, Canada)." Paleontological Society Special Publications 8 (1996): 16. http://dx.doi.org/10.1017/s2475262200000186.
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Sun, Zhixin, Han Zeng, and Fangchen Zhao. "First occurrence of the Cambrian arthropod Sidneyia Walcott, 1911 outside of Laurentia." Geological Magazine 157, no. 3 (August 28, 2019): 405–10. http://dx.doi.org/10.1017/s0016756819000864.
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AbstractThe arthropod Sidneyia Walcott, 1911 is a remarkable animal of the Burgess Shale biota (Cambrian Miaolingian, Wuliuan; British Columbia, Canada), which has not been confidently reported from other Cambrian Konservat-Lagerstätten. Here we report the discovery of Sidneyia cf. inexpectans from the Wuliuan Mantou Formation of North China, which substantially expands the known palaeogeographical distribution of this genus. Our discovery suggests that Sidneyia had much greater dispersal ability than hitherto thought. It also confirms the presence of exceptionally preserved fossils in the Wuliuan Mantou Formation, one of the rare Burgess Shale-type deposits of North China.
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Verdun, Amy. "The Federal Features of the EU: Lessons from Canada." Politics and Governance 4, no. 3 (August 11, 2016): 100–110. http://dx.doi.org/10.17645/pag.v4i3.598.
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There has been a rise and fall in interest in federalism in the context of European integration. This article assesses the federal nature of the EU. It draws in particular on the work of Michael Burgess who has been one of the key thinkers on this issue. Because there are many types of ‘federalisms’ available across the globe, it is helpful to make a comparison with another political system to offer a base line. In this article I explore to what extent the EU already has federal features. With the help of the work of Burgess I seek to look beyond the specific characteristics of the EU and reflect on how a comparison with this other polity can offer us insights into what is going on within the EU political system. Drawing on the comparison with Canada, I seek to identify the characteristics of the EU that are already those of a federation. Therefore, the guiding question of this article is: compared to Canada, what particular features does the EU have that reminds us of a federation and what features is it still lacking? It finds that the EU has a considerable amount of federal features (federation), but that a federal tradition, a federal ideology and advocacy to a federal goal (federalism) are mostly absent.
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Minter, Nicholas J., M. Gabriela Mángano, and Jean-Bernard Caron. "Skimming the surface with Burgess Shale arthropod locomotion." Proceedings of the Royal Society B: Biological Sciences 279, no. 1733 (November 9, 2011): 1613–20. http://dx.doi.org/10.1098/rspb.2011.1986.
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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.
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Kimmig, Julien, and Brian R. Pratt. "Soft-bodied biota from the middle Cambrian (Drumian) Rockslide Formation, Mackenzie Mountains, northwestern Canada." Journal of Paleontology 89, no. 1 (January 2015): 51–71. http://dx.doi.org/10.1017/jpa.2014.5.
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AbstractA new Burgess Shale-type Lagerstätte is described from the middle Cambrian (Series 3, Drumian) Rockslide Formation of the Mackenzie Mountains, Northwest Territories, Canada. The Rockslide Formation is a unit of deeper water ramp to slope, mixed carbonate, and siliciclastic facies deposited on the northwestern margin of Laurentia. At the fossil-bearing locality, the unit onlaps a fault scarp cutting lower Cambrian sandstones. There it consists of a succession of shale and thick-laminated to thin-bedded lime mudstone, calcareous sandstone, and greenish-colored calcareous mudstone, overlain by shallower water dolostones of the Avalanche Formation, which is indicative of an overall progradational sequence. The Rockslide Formation is of similar age to the Wheeler and Marjum formations of Utah, belonging to theBolaspidellaBiozone. Only two 1 m thick units of greenish mudstone exhibit soft-bodied preservation, with most specimens coming from the lower interval. However, the biota is common but not as diverse as that of other Lagerstätten such as the Burgess Shale in its type area. The shelly fauna is dominated by the hyolithHaplophrentis carinatusMatthew, 1899 along with sparse linguliformean brachiopods, agnostoid arthropods, and ptychoparioid trilobites. The nonmineralized biota includes the macrophytic algaMargaretia dorusWalcott, 1911, priapulid worms, and the carapaces of a number of arthropods. The arthropods belong toIsoxys mackenziensisn. sp.,Tuzoiacf.T. guntheriRobison and Richards, 1981;Branchiocaris? sp.,Perspicaris?dilatusRobison and Richards, 1981; and bradoriids, along with fragments of arthropods of indeterminate affinities. The style of preservation indicates that most soft parts underwent complete biodegradation, leaving just the more resistant materials such as chitinous arthropod cuticles. The range of preservation and similarity to the coeval biotas preserved in Utah suggests that the composition of this Lagerstätte is probably representative of the community living on the relatively deep-water ramp or slope during middle Cambrian time in Laurentia. This would argue that the extraordinary diversity of the Burgess Shale at Mount Field is anomalous.
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Rigby, J. Keith, Lloyd F. Gunther, and Freida Gunther. "The first occurrence of the Burgess Shale demosponge Hazelia palmata Walcott, 1920, in the Cambrian of Utah." Journal of Paleontology 71, no. 6 (November 1997): 994–97. http://dx.doi.org/10.1017/s0022336000035976.
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A single specimen of Hazelia palmata Walcott, 1920, was collected from the Middle Cambrian Marjum Formation near Marjum Pass, in the central House Range, western Utah. This is a first occurrence of the species outside the Burgess shale region of British Columbia, Canada. The flattened oval impression of the monaxonid demosponge shows characteristic tufts and spicule structures of the species.
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Sumrall, Colin D., and Samuel Zamora. "A columnal-bearing eocrinoid from the Cambrian Burgess Shale (British Columbia, Canada)." Journal of Paleontology 89, no. 2 (March 2015): 366–68. http://dx.doi.org/10.1017/jpa.2014.54.
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AbstractA new eocrinoid ?Ubaghsicystis sp. from the middle Cambrian (Series 3, Stage 5) Burgess Shale is reported based on a single known specimen. This species extends the stratigraphic range of columnal-bearing eocrinoids in Laurentia significantly from Cambrian Stage 7 (Guzhangian) to Stage 5. It increases the diversity of echinoderms in this well-known fossil-Lagerstätte, provides the oldest evidence of columnal-bearing eocrinoids from Laurentia, and further documents the cosmopolitan distribution of middle Cambrian echinoderm clades.
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Anderson, Ross P., Nicholas J. Tosca, Erin E. Saupe, Jon Wade, and Derek E. G. Briggs. "Early formation and taphonomic significance of kaolinite associated with Burgess Shale fossils." Geology 49, no. 4 (November 20, 2020): 355–59. http://dx.doi.org/10.1130/g48067.1.
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Abstract The role of minerals in Burgess Shale–type fossilization is controversial, particularly that of the clay mineral kaolinite. Kaolinite may have formed on carcasses or attached to them as they decayed, stabilizing organic matter. Alternatively, kaolinite may have formed during metamorphism, playing no role in the preservation of soft tissues. Evaluating the formation and taphonomic role of kaolinite is difficult, because the mineralogy of Burgess Shale–type fossils is incompletely known. We used in situ selected-area X-ray diffraction to constrain the mineralogy of fossils from the classic Burgess Shale Formation in British Columbia, Canada. Fossils can be distinguished from the matrix that surrounds them by the presence of dolomite, kaolinite, and pyrite. Chlorite may be more abundant in the matrix. The preferential survival of kaolinite in association with fossils provides evidence of early diagenetic clay-organic interactions that protected the clay from metamorphic transformation. Kaolinite likely played a crucial role in fossilization, inhibiting the growth of heterotrophic bacteria and aiding polymerization of soft tissue biomolecules. This may result in biases in soft-tissue preservation to areas and times where kaolinite was prevalent.
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Legg, David A., and Jean-Bernard Caron. "New Middle Cambrian bivalved arthropods from the Burgess Shale (British Columbia, Canada)." Palaeontology 57, no. 4 (November 18, 2013): 691–711. http://dx.doi.org/10.1111/pala.12081.
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Mankiewicz, Carol. "Obruchevella and other microfossils in the Burgess Shale: preservation and affinity." Journal of Paleontology 66, no. 5 (September 1992): 717–29. http://dx.doi.org/10.1017/s0022336000020758.
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Charles D. Walcott's thin sections of the Middle Cambrian Burgess Shale of British Columbia, Canada, have yielded many specimens of the helically coiled microfossil Obruchevella delicata, as well as fragments of the cyanobacteria Marpolia and Morania, sphaeromorph acritarchs, and sclerites of the enigmatic metazoan Wiwaxia. Obruchevella of the Burgess Shale displays a spectrum of preservation styles ranging from tangled masses to well-developed helixes. All Obruchevella specimens are preserved in three dimensions, which suggests original skeletalization or early post-mortem mineralization of the organism. Morphologic analysis of Obruchevella supports an affinity with modern helical cyanobacteria. Study of all reported occurrences of Obruchevella indicates that: 1) the genus has been overly split into seventeen species; 2) no correlation between size and age of Obruchevella exists; and 3) most Obruchevella specimens are tightly coiled and have helix diameters four to six times their filament diameters.
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García-Bellido, Diego C., and Desmond H. Collins. "A new study of Marrella splendens (Arthropoda, Marrellomorpha) from the Middle Cambrian Burgess Shale, British Columbia, Canada." Canadian Journal of Earth Sciences 43, no. 6 (June 1, 2006): 721–42. http://dx.doi.org/10.1139/e06-012.
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Study of over 1000 specimens of Marrella splendens Walcott, 1912, out of the more than 9000 collected by the Royal Ontario Museum (ROM) since 1975, has produced new information on the anatomy, functional morphology, and behaviour of this most common arthropod in the Burgess Shale fauna. Among the new features recognized is the distinction between the alimentary canal and circulatory system; where the former is generally three-dimensional and slightly reflective, the latter never presents any relief and is very reflective. A larger range of size is now known, from 2.4 to 24.5 mm in length, with small individuals possessing 17 body segments to large specimens with more than 26 body segments, representing an almost complete ontogenetic series. The second pair of "antennae" is now interpreted as swimming appendages, since the five distal segments are dorsoventrally compressed, fringed with setae and with a considerable blood supply, providing a paddlelike appendage capable of producing a considerable propelling force. The ROM collections extend the geographical distribution of Marrella 13 km to the southeast and the stratigraphical range through the lowest five members of the Burgess Shale Formation.
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Culliney, Thomas W. "PREDATION ON ADULT PHYLLOTRETA FLEA BEETLES BY PODISUS MACULIVENTRIS (HEMIPTERA: PENTATOMIDAE) AND NABICULA AMERICOLIMBATA (HEMIPTERA: NABIDAE)." Canadian Entomologist 118, no. 7 (July 1986): 731–32. http://dx.doi.org/10.4039/ent118731-7.
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On three occasions in late August 1985, during the course of a study of the arthropod community associated with collards (Brassica oleracea var. acephala) (Cruciferae) in central New York State, two species of predaceous Heteroptera, the spined soldier bug, Podisus maculiventris (Say), and Nabicula americolimbata (Carayon), were observed feeding on adult flea beetles of the genus Phyllotreta. Evidence for predation on adult flea beetles is rare. Tahvanainen and Root (1972) and Kareiva (1985) reported practically no predation on adult Phyllotreta cruciferae (Goeze) in central New York, but scattered observations in Canada have documented occasional attacks on adult crucifer-infesting flea beetles by various insect predators (Gerber and Osgood 1975; Burgess 1977, 1980, 1982). This is the first record of predation on adult flea beetles by P. muculiventris and N. americolimbata. Burgess (1982) noted predation on adult P. cruciferae by another nabid, Nabis alternatus Parshley.
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Montero, Ángel, Carmen Diéguez, and Diego García-Bellido. "Ejemplares de la Phyllopod Bed-Burgess Shale (Cámbrico Medio) en el Museo Nacional de Ciencias Naturales-CSIC (Madrid, Espana)." Spanish Journal of Palaeontology 13, no. 3 (February 27, 2022): 143. http://dx.doi.org/10.7203/sjp.23987.
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A collection of fossil invertebrates from well-known North American sites is hosted at the Museo Nacional de Ciencias Naturales-CSIC (MNCN-CSIC) of Madrid. This collection was a result of an exchange between this Institution and the Smithsonian Institution of Washington in the sixties of this century. In this collection there are eigth items from the Walcott's Quarry site of the Burgess Shale (British Columbia, Canada). It consists of twelve specimens included in the Kingdom Monera (one phylum) and Kingdom Animalia (six phyla).
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Balakrishnan, T. R., and George K. Jarvis. "Is the Burgess concentric zonal theory of spatial differentiation still applicable to urban Canada?" Canadian Review of Sociology/Revue canadienne de sociologie 28, no. 4 (July 14, 2008): 526–39. http://dx.doi.org/10.1111/j.1755-618x.1991.tb00168.x.
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Pratt, Brian R., and Julien Kimmig. "Extensive bioturbation in a middle Cambrian Burgess Shale–type fossil Lagerstätte in northwestern Canada." Geology 47, no. 3 (January 18, 2019): 231–34. http://dx.doi.org/10.1130/g45551.1.
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O'Brien, Lorna J., and Jean-Bernard Caron. "A New Stalked Filter-Feeder from the Middle Cambrian Burgess Shale, British Columbia, Canada." PLoS ONE 7, no. 1 (January 18, 2012): e29233. http://dx.doi.org/10.1371/journal.pone.0029233.
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Butterfield, Nicholas J. "Burgess Shale-type fossils from a Lower Cambrian shallow-shelf sequence in northwestern Canada." Nature 369, no. 6480 (June 1994): 477–79. http://dx.doi.org/10.1038/369477a0.
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Moysiuk, J., and J. B. Caron. "Burgess Shale fossils shed light on the agnostid problem." Proceedings of the Royal Society B: Biological Sciences 286, no. 1894 (January 16, 2019): 20182314. http://dx.doi.org/10.1098/rspb.2018.2314.
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Agnostids (agnostinids and eodiscinids) are a widespread and biostratigraphically important group of Cambro-Ordovician euarthropods whose evolutionary affinities have been highly controversial. Their dumbbell-shaped calcified tergum was traditionally suggested to unite them with trilobites, but agnostinids have alternatively been interpreted as stem-crustaceans, based on Orsten larval material from the Cambrian of Sweden. We describe exceptionally preserved soft tissues from mature individuals of the agnostinids Peronopsis and Ptychagnostus from the middle Cambrian (Wuliuan Stage) Burgess Shale (Walcott Quarry and Marble Canyon, British Columbia, Canada), facilitating the testing of alternative hypotheses. The digestive tract includes conspicuous ramifying cephalic diverticulae. The cephalon carries one pair of elongate spinous antennules projecting to the front, two pairs of appendages with distally setose, oar-like exopods, and three pairs of presumably biramous appendages with endopods sporting club-shaped exites. The trunk bears five appendage pairs, at least the first two of which are similar to the posteriormost cephalic pairs. The combined evidence supports a nektobenthic and detritivorous lifestyle for agnostinids. A head with six appendiferous segments contrasts strikingly with the four known in trilobites and five typical of mandibulates. Agnostinids are retrieved as the sister group to polymeroid trilobites in our phylogeny, implying that crustacean-like morphologies evolved homoplastically. This result highlights the variability in segmental composition of the artiopodan head. Finally, our study emphasizes the continued role of Burgess Shale-type fossils in resolving the affinities of problematic biomineralizing taxa.
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Allison, Peter A., and Carlton E. Brett. "In situ benthos and paleo-oxygenation in the Middle Cambrian Burgess Shale, British Columbia, Canada." Geology 23, no. 12 (1995): 1079. http://dx.doi.org/10.1130/0091-7613(1995)023<1079:isbapo>2.3.co;2.
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Vidal, G., and J. S. Peel. "Acritarchs from the Buen Formation (Lower Cambrian), North Greenland." Rapport Grønlands Geologiske Undersøgelse 137 (December 31, 1988): 54. http://dx.doi.org/10.34194/rapggu.v137.8014.
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Siliciclastic sediments of the Buen Formation of North Greenland yield the earliest Cambrian fossils known from North Greenland, with the exception of cyanobacteria described from dolomites of the underlying Portfjeld Formation (see Peel, this report). The fauna is dominated by olenellid and nevadiid trilobites indicating an Early Cambrian age (Poulsen, 1974; Blaker, this report) but hyolithids, bradoriids, sponges and other fossils also occur. Bergstrom & Peel (this report) described trace fossils from the Buen Formation. Of particular interest is the recent discovery of lightly skeletised arthropods comprising an assemblage similar to that of the Middle Cambrian Burgess shale of Canada (Conway Morris et al., 1987).
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Morris, Simon Conway. "A redescription of a rare chordate, Metaspriggina Walcotti Simonetta and Insom, from the Burgess Shale (Middle Cambrian), British Columbia, Canada." Journal of Paleontology 82, no. 2 (March 2008): 424–30. http://dx.doi.org/10.1666/06-130.1.
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Until Recently, our understanding of the earliest history of the fish has been fragmentary in terms of the fossil record and conjectural with respect to many details of phylogeny. Fortunately, significant new information has become available in recent years, most notably from the discoveries of at least three taxa of agnathan fish from the Lower Cambrian Chengjiang Lagerstätte of Yunnan, China (Shu et al., 1999, 2003; Shu, 2003; see also Hou et al., 2002; Hou et al., 2004, p. 192-193; Zhang and Hou, 2004). Two of the taxa (Haikouichthys and Zhangjianichthys) are represented by numerous specimens, but it is noteworthy that amongst the forty-odd Burgess Shale-type occurrences apart from the Chengjiang Lagerstätte, chordates (or indeed cephalochordates and urochordates) are otherwise unknown. The one exception is the Burgess Shale itself, characterized by the rather enigmatic Pikaia gracilens (Conway Morris, 1982, 1998) and the much rarer chordate described herein. Apart from this exceptionally preserved material, the fossil record effectively only begins in the Ordovician (e.g., Sansom et al., 2001, 2005; Sansom and Smith, 2005), in as much putative fish scales from the latest Cambrian (Young et al., 1996) may be better interpreted as arthropodan (see Smith et al., 2001, p. 78). The difficulties of interpreting what is overall an extremely patchy record are further compounded by the fact that the relevance to this early history of the extant agnathan hagfish and lamprey has remained (and indeed to some extent remains) problematic, given the uncertainty as to which of the presumed archaic features have been overprinted by specializations for modes of life that might have had little counterpart in the ancestral forms.
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GARCÍA-BELLIDO, DIEGO C., and DESMOND COLLINS. "REASSESSMENT OF THE GENUS LEANCHOILIA (ARTHROPODA, ARACHNOMORPHA) FROM THE MIDDLE CAMBRIAN BURGESS SHALE, BRITISH COLUMBIA, CANADA." Palaeontology 50, no. 3 (May 2007): 693–709. http://dx.doi.org/10.1111/j.1475-4983.2007.00649.x.
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Gozalo, Rodolfo, Mª Eugenia Dies-Álvarez, José Antonio Gámez VIintaned, Juan B. Chirivella, and Eladio Liñan. "Presence of Naraoia Walcott, 1912 (Nektaspida, Arthropoda) in the middle Cambrian of Europe (Murero, NE Spain)." Spanish Journal of Palaeontology 33, no. 1 (October 31, 2018): 83. http://dx.doi.org/10.7203/sjp.33.1.13243.
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The genus Naraoia Walcott, 1912, a Burgess Shale-type fossil known from the lower and middle Cambrian of British Columbia (Canada), Idaho and Utah (USA), as well as from Yunnan and Guizhou provinces (China), is now reported from the middle Cambrian of Murero (Zaragoza, Spain), which is the first record in the Acadobaltic province. The only fragmented specimen found is determined as Naraoia sp., its age being Pardailhania multispinosa Zone (Drumian Stage). This new datum reinforces the hypothesis of the existence of a cosmopolitan faunal substrate in early Cambrian times, which is to some extent refl ected in the mid Cambrian by faunal groups of low evolutionary potential as the family Naraoiidae and other soft-bodied fossil taxa.
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Nedin, Christopher. "Palaeontology and palaeoecology of the Lower Cambrian Emu Bay Shale Lagerstätten, Kangaroo Island, South Australia." Paleontological Society Special Publications 6 (1992): 221. http://dx.doi.org/10.1017/s2475262200007814.
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The last two decades have seen the status of deposits containing soft bodied Cambrian fossils rise from geological curios into one of the foundations of modern thinking on early metazoan evolution and ecology. Some thirty of these soft bodied assemblages or Lagerstätten, resembling the Burgess Shale fauna are now known. One of these is the Lower Cambrian Emu Bay Shale fauna from Kangaroo Island, South Australia.The Emu Bay Shale has been mapped in two localities approx. 8 km (5 miles) apart on the northern coast of Kangaroo Island, at Emu Bay and at Big Gully. Previous investigations into the numerically abundant Lagerstätten fauna at Big Gully have highlighted its unusually pauperate diversity, with only some seven species described. The preservation is also unusual, comprising replacement by iron stained calcite. The fauna is confined to a 10 m thick basal siltstone. The age of the deposit is believed to be mid to upper Botomian and is thus marginally older than Early Cambrian soft bodied assemblages found on the North American continent and predating the better known Middle Cambrian Burgess Shale.In late 1991, a study of the Emu Bay Shale was undertaken to document the palaeontology and palaeoecology of the fauna. Preliminary findings, whilst increasing the number of species, confirm the pauperate diversity of the fauna. The new forms include several specimens of anomalocarid appendages. These not only represent the first occurrence of this form in Australia, but also the first occurrence outside the Burgess Shale of anomalocarid appendages with 11 segments, as compared with the more common and widespread 14 segment appendages. This connection may be important in the light of recent palaeoreconstructions which show the west coast of Canada and eastern Australia in close proximity during the early Cambrian. Also the spatial arrangement of the appendages indicates that anomalocarids may have shoaled and hunted in groups. They appear to have fed on the sea bottom, possibly using their appendages to probe the muddy bottom for shallowly buried prey as well as for capturing and transporting prey to the mouth.The assemblage appears to be dominated by the preservation of hard or permineralized body parts. However, abundant calcified ribbon-like structures concentrated on some bedding planes have yet to be classified. Several exceptionally preserved specimens of Myoscolex appear to have a series of metamerically repeated ‘paddle-like’ appendages, similar to some forms from the Burgess Shale, thus casting doubt on an annelid affinity.The assemblage appears representative of a deep water, low oxygen environment prone to periodic anoxia, possibly similar to the accretionary environment of the Burgess Shale.The Emu Bay Shale at Emu Bay exhibits a shelly assemblage, mostly comprised of disarticulated Hsuaspis exuvia with occasional small Redlichia exuvia and hyolithids. No calcite replacement is evident. The location represents current swept, probably shallow water environment.
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Thompson, Cheryl. "Casting Blackface in Canada: Unmasking the History of ‘White and Black’ Minstrel Shows." Canadian Theatre Review 193 (February 1, 2023): 16–20. http://dx.doi.org/10.3138/ctr.193.004.
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Blackface minstrelsy was the dominant form of mass entertainment for over a century, from the 1840s through the 1940s. In Canada, there has been little scholarly research into the topic but for the work of Stephen Johnson and, in recent years, the works I have published on the subject. One of the reasons blackface has been understudied is the dearth of attention paid to histories of slavery. By exploring the history of casting blackface productions, both ‘white’ minstrelsy (white performers blackening up to imitate the song and dance of African-Americans) and ‘Black’ minstrelsy (Black performers in and out of blackface performing caricatures of themselves in front of majority-white audiences), we gain an understanding of how these shows were produced, and what audiences found appealing about them. Canada has produced its own blackface stars, like Colin ‘Cool’ Burgess (1840–1905) and Calixa Lavallée (1842–1891), both of whom toured the United States and Canada in the late nineteenth century and who not only performed in blackface but also produced songs, some of which are still known today, like “O Canada,” the Canadian national anthem, composed by Lavallée in 1880. Additionally, what the history of casting blackface in Canada shows is a long-standing desire among white audiences for depictions of the American Plantation South that often included the participation of local actors like playwright and writer Charles Wesley Handscomb (1867–1906), who moved to Winnipeg in 1879, who were often cast in touring minstrel productions to sing in blackface.
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Van Wychen, Wesley, Luke Copland, Laurence Gray, Dave Burgess, Brad Danielson, and Martin Sharp. "Spatial and temporal variation of ice motion and ice flux from Devon Ice Cap, Nunavut, Canada." Journal of Glaciology 58, no. 210 (2012): 657–64. http://dx.doi.org/10.3189/2012jog11j164.
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AbstractSpeckle tracking of repeat RADARSAT-2 fine-beam imagery acquired over 24 day periods in March 2009 allowed the creation of updated surface motion maps for the entire Devon Ice Cap, Canada. Error analysis indicates that speckle tracking can determine ice motion to an accuracy of ~5 ma-1. Comparisons with earlier velocity maps from the mid-1990s and 2000 reveal velocity patterns that largely agree with flow regimes described previously. However, motion determined along East5 Glacier indicates an increase in surface velocities between the studies. Additionally, Southeast2 Glacier has significantly accelerated over the past decade, with velocities greater in 2009 than in the early 1990s along almost the entire length of the glacier. This is likely indicative of a surge. Present-day total mass loss from Devon Ice Cap due to iceberg calving is calculated as 0.40 ± 0.09 Gta-1, similar to that reported by Burgess and others (2005), with Belcher Glacier accounting for ~42% of the entire loss.
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PATES, STEPHEN, and ALLISON C. DALEY. "The Kinzers Formation (Pennsylvania, USA): the most diverse assemblage of Cambrian Stage 4 radiodonts." Geological Magazine 156, no. 07 (July 30, 2018): 1233–46. http://dx.doi.org/10.1017/s0016756818000547.
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AbstractRadiodonta, apex Cambrian predators such as Anomalocaris have been known from the Kinzers Formation (Cambrian Series 2, Stage 4 – Pennsylvania, USA) for nearly 100 years. Work over the last ten years, mainly on radiodont material from the Chengjiang (Cambrian Series 2, Stage 3 – Yunnan, China) and Burgess Shale (Miaolingian, Wuliuan – British Columbia, Canada), has greatly improved our knowledge of the diversity and disparity of radiodonts and their frontal appendages, including the description of new species, genera and families. Previous work identified two species of radiodonts from the Kinzers Formation: Anomalocaris pennsylvanica Resser, 1929 and Anomalocaris? cf. pennsylvanica based on isolated frontal appendage material (Briggs, 1979). A restudy of Kinzers Formation material shows that only some of the specimens can be confirmed as Anomalocaris pennsylvanica, and a number of specimens previously attributed to Anomalocaris in fact belong to other more recently discovered radiodont genera Amplectobelua and Tamisiocaris. This reinterpretation makes the Kinzers Formation the most diverse Cambrian Stage 4 Burgess Shale Type Lagerstätten in terms of number of radiodont species. This assemblage includes the youngest known Tamisiocaris and the first from outside Greenland, the only Amplectobelua from Stage 4 and the oldest from Laurentia, two specimens tentatively assigned to the recently described Chengjiang genus Laminacaris, and the endemic Anomalocaris pennsylvanica. The identification of these new radiodont taxa increases the total known diversity of the Kinzers Formation to more than ten species, and so it should now be considered a Tier 2 Lagerstätte.
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Zhao, Fangchen, Jean-Bernard Caron, David J. Bottjer, Shixue Hu, Zongjun Yin, and Maoyan Zhu. "Diversity and species abundance patterns of the Early Cambrian (Series 2, Stage 3) Chengjiang Biota from China." Paleobiology 40, no. 1 (2014): 50–69. http://dx.doi.org/10.1666/12056.
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Lagerstättenfrom the Precambrian–Cambrian transition have traditionally been a relatively untapped resource for understanding the paleoecology of the “Cambrian explosion.” This quantitative paleoecological study is based on 10,238 fossil specimens belonging to 100 animal species, 11 phyla, and 15 ecological categories from the lower Cambrian (Series 2, Stage 3) Chengjiang biota (Mafang locality near Haikou, Yunnan Province, China). Fossils were systematically collected within a 2.5-meter-thick sequence divided into ten stratigraphic intervals. Each interval represents an induced time-averaged assemblage of various event (obrution) beds of unknown duration. Overall, the different fossil assemblages are taxonomically and ecologically similar, suggesting the presence of a single community type recurring throughout the Mafang section. The Mafang community is dominated by epibenthic vagile hunters or scavengers, sessile suspension feeders, and infaunal vagile hunters or scavengers represented primarily by arthropods, brachiopods, and priapulids, respectively. Most species have low abundance and low occurrence frequencies, whereas a few species are numerically abundant and occur frequently. Overall, in structure and ecology the Mafang community is comparable to the Middle Cambrian (Series 3, Stage 5) Burgess Shale biota (Walcott Quarry, Yoho National Park, British Columbia, Canada). This suggests that, despite variations in species identity within taxonomic and ecological groups, the structure and ecology of Cambrian Burgess Shale-type communities remained relatively stable until at least the Middle Cambrian (Series 3, Stage 5) in subtidal to relatively deep-water offshore settings in siliciclastic soft-substrate environments.
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Conway Morris, Simon. "Ediacaran survivors." Paleontological Society Special Publications 6 (1992): 69. http://dx.doi.org/10.1017/s2475262200006298.
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Ediacaran taxa are a characteristic element of latest Precambrian biotas, with an effectively global distribution. Their time range is not well understood, but with one possible exception from western Canada Ediacaran faunas appear always to post-date the late Precambrian glaciations. There is also growing evidence that many Ediacaran taxa disappeared before the Precambrian-Cambrian boundary. These disappearances traditionally have been ascribed to changes in taphonomic circumstances, but a series of extinctions is a plausible alternative. Ediacaran fossils pose two major problems: Notwithstanding the reasons for their disappearance shortly before the Precambrian-Cambrian boundary, was their demise total or did some forms persist into the Cambrian? Second, is the traditional view that Ediacaran taxa are metazoans, many of a cnidarian grade, correct? Recently Seilacher, Bergström and others have argued that the Ediacaran organisms have a distinctive bauplan, difficult to reconcile with known phyla and possibly different from any metazoan.In the Cambrian, Burgess Shale-type faunas are the principal source of information on soft-bodied metazoans. The differences between them and Ediacaran assemblages are largely self-evident, but there is now unequivocal evidence for at least one Ediacaran survivor from the Middle Cambrian Burgess Shale of British Columbia. This is a sea-pen-like animal, known from three specimens (one adult about 20 cm in length, and two juveniles). The fossils consist of a broad frond, with branches arising from a central axis on one side, while the opposite side is smooth apart from longitudinal ridges. The frond extends into a blunt holdfast that presumably was embedded in the muddy silt of the sea floor. This fossil is strikingly similar to the Ediacaran taxon Charniodiscus, best known from South Australia. The Burgess Shale example shows two important features. The first are pustule-like structures, possibly zooids, both on the branches and adjacent to the axis. The second feature is evidence for connections between the branches and axis, possibly representing canals. These features both support a comparison with extant pennatulaceans, and suggest that at least some Ediacaran taxa are correctly assigned to the metazoans.Also occurring in the Burgess Shale is an enigmatic bag-like organism Mackenzia costalis. Clear evidence exists for it being benthic, but its mode of feeding is uncertain. The interior appears to have consisted largely of a spacious cavity, probably sub-divided by longitudinal partitions. In addition, an elongate strand may represent a discrete organ, perhaps connected with digestion or reproduction. No exact equivalent to Mackenzia appears to occur in Ediacaran assemblages, but bag-like taxa are a common component. These include erniettids, best known from Namibia, and Platypholina, from the White Sea region of Russia.
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García-Bellido, Diego C., Jean Vannier, and Desmond Collins. "Soft-Part Preservation in two Species of the ArthropodIsoxysfrom the Middle Cambrian Burgess Shale of British Columbia, Canada." Acta Palaeontologica Polonica 54, no. 4 (December 2009): 699–712. http://dx.doi.org/10.4202/app.2009.0024.
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Butterfield, N. J., and C. J. Nicholas. "Burgess Shale-type preservation of both non-mineralizing and ‘shelly’ Cambrian organisms from the Mackenzie Mountains, northwestern Canada." Journal of Paleontology 70, no. 6 (November 1996): 893–99. http://dx.doi.org/10.1017/s0022336000038579.
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Lower to Middle Cambrian shales of the Mount Cap Formation in the Mackenzie Mountains, northwestern Canada, host a variety of Burgess Shale-type macrofossils, including anomalocarid claws, several taxa of bivalved arthropod, articulated hyolithids, and articulated chancelloriids. Hydrofluoric acid processing has also yielded a broad range of organic-walled fossils, most of which are derived from forms more typically known as shelly fossils; e.g., trilobites, inarticulate brachiopods, small shelly fossils (SSF), hyolithids, and chancelloriids. Organic-walled hyolithids include conchs, opercula and helens; the proximal articulation of the helens is erosive, suggesting that they were formed “instantaneously” and periodically replaced. Organic-walled chancelloriid sclerites exhibit a polygonal surface texture and an inner “pith” of dark granular material with distally oriented conoidal divisions; such a pattern is similar to that seen in the fibers of some modern horny sponges and points to a poriferan relationship for the chancelloriids. The robust nature but minimal relief of most of these fossils suggests that primary biomineralization was minimal.
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Legg, David. "Multi-Segmented Arthropods from the Middle Cambrian of British Columbia (Canada)." Journal of Paleontology 87, no. 3 (May 2013): 493–501. http://dx.doi.org/10.1666/12-112.1.
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A new arthropod, Kootenichela deppi n. gen. n. sp., is described from the Stanley Glacier exposure of the middle Cambrian (Series 3, Stage 5) Stephen Formation in Kootenay National Park (British Columbia, Canada). This taxon possesses a number of primitive arthropod features such as an elongate, homonomous trunk (consisting of at least 29 segments), poorly sclerotised trunk appendages, and large pedunculate eyes associated with an anterior (ocular) sclerite. The cephalon encompasses a possible antenna-like appendage and enlarged raptorial appendages with a bipartite peduncle and three spinose distal podomeres, indicative of megacheiran (“great-appendage” arthropod) affinities. The relationships of megacheirans are controversial, with them generally considered as either stem-euarthropods or a paraphyletic stem-lineage of chelicerates. An extensive cladistic analysis resolved Kootenichela as sister-taxon to the enigmatic Worthenella cambria from the middle Cambrian (Series 3, Stage 5), Burgess Shale Formation in Yoho National Park (British Columbia), which is herein reinterpreted as a megacheiran arthropod. Based on their sister-group relationship, both taxa were placed in the new family Kootenichelidae, to which Pseudoiulia from the Chengjiang biota is also tentatively assigned. All of these taxa possess an elongate, multi-segmented body and subtriangular exopods. This family occupies a basal position within a paraphyletic Megacheira, the immediate outgroup of Euarthropoda (crown-group arthropods). The resultant topology indicates that analyses that have resolved megacheirans as stem-chelicerates have done so because they have rooted on inappropriate taxa, e.g., trilobitomorphs and marrellomorphs.
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Moysiuk, J., and J. B. Caron. "A new hurdiid radiodont from the Burgess Shale evinces the exploitation of Cambrian infaunal food sources." Proceedings of the Royal Society B: Biological Sciences 286, no. 1908 (July 31, 2019): 20191079. http://dx.doi.org/10.1098/rspb.2019.1079.
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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.
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Nanglu, Karma, and Jean-Bernard Caron. "Symbiosis in the Cambrian: enteropneust tubes from the Burgess Shale co-inhabited by commensal polychaetes." Proceedings of the Royal Society B: Biological Sciences 288, no. 1951 (May 26, 2021): 20210061. http://dx.doi.org/10.1098/rspb.2021.0061.
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The in situ preservation of animal behaviour in the fossil record is exceedingly rare, but can lead to unique macroecological and macroevolutionary insights, especially regarding early representatives of major animal clades. We describe a new complex ecological relationship from the middle Cambrian Burgess Shale (Raymond Quarry, Canada). More than 30 organic tubes were recorded with multiple enteropneust and polychaete worms preserved within them. Based on the tubicolous nature of fossil enteropneusts, we suggest that they were the tube builders while the co-preserved polychaetes were commensals. These findings mark, to our knowledge, the first record of commensalism within Annelida and Hemichordata in the entire fossil record. The finding of multiple enteropneusts sharing common tubes suggests that either the tubes represent reproductive structures built by larger adults, and the enteropneusts commonly preserved within are juveniles, or these enteropneusts were living as a pseudo-colony without obligate attachment to each other, and the tube was built collaboratively. While neither hypothesis can be ruled out, gregarious behaviour was clearly an early trait of both hemichordates and annelids. Further, commensal symbioses in the Cambrian may be more common than currently recognized.
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Izquierdo-López, Alejandro, and Jean-Bernard Caron. "A possible case of inverted lifestyle in a new bivalved arthropod from the Burgess Shale." Royal Society Open Science 6, no. 11 (November 2019): 191350. http://dx.doi.org/10.1098/rsos.191350.
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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.
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Yugan, Jin, Hou Xianguang, and Wang Huayu. "Lower Cambrian pediculate lingulids from Yunnan, China." Journal of Paleontology 67, no. 5 (September 1993): 788–98. http://dx.doi.org/10.1017/s0022336000037057.
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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.
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Johnston, Paul A., Kimberley J. Johnston, Christopher J. Collom, Wayne G. Powell, and Robyn J. Pollock. "Palaeontology and depositional environments of ancient brine seeps in the Middle Cambrian Burgess Shale at The Monarch, British Columbia, Canada." Palaeogeography, Palaeoclimatology, Palaeoecology 277, no. 1-2 (June 2009): 86–105. http://dx.doi.org/10.1016/j.palaeo.2009.02.013.
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LONSDALE, OWEN. "The Liriomyza (Agromyzidae: Schizophora: Diptera) of California." Zootaxa 2850, no. 1 (April 29, 2011): 1. http://dx.doi.org/10.11646/zootaxa.2850.1.1.
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The Californian species of Liriomyza Mik are revised, including descriptions, illustrations, photographs and a key to species. Sixty-three species are now known to occur in the state, 12 of which are described here as new: L. bispinula, L. conclavis, L. cunicularia, L. merga, L. miserabilis, L. nebulosa, L. parabella, L. phyllodes, L. projecta, L. salpingion, L. tricornis and L. trixivora. Liriomyza virginica Spencer is included as a junior synonym of L. helianthi Spencer, and L. similis Spencer is included as a synonym of L. artemisiae Spencer. Two species are newly recorded in the United States: L. equiseti Meijere, previously known from Canada and Europe, and L. montana Sehgal, previously known from Canada. A number of specimens of L. brassicae (Riley) have been identified as potential new host “races” or species. Morphological characters are provided to diagnose the sister species L. huidobrensis (Blanchard) and L. langei Frick, previously recognizable only on the basis of molecular data. Numerous new state, county and host records are also presented, and hosts are compared for five of the most common North American agricultural pests: L. brassicae, L. huidobrensis, L. langei, L. sativae Blanchard and L. trifolii (Burgess). California contains the highest diversity of Liriomyza known to occur in North America, containing approximately 70% of all described species known from the lower 48 states.
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Pisera, A. "Palaeontology of sponges — a review." Canadian Journal of Zoology 84, no. 2 (February 1, 2006): 242–61. http://dx.doi.org/10.1139/z05-169.
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The fossil record of sponges is a very old one, and begins in the Precambrian, but is rather incomplete. Only those sponges with a rigid skeleton, i.e., Hexactinosida and Lychniscosida (both hexactinellids), lithistids (demosponges with desmas), and sponges with a massive calcareous skeleton (polyphyletic demosponges and Calcarea) have a more or less continuous fossil record that is, however, inadequately studied, especially from the Tertiary. The beginning of sponge diversification during the Cambrian is relatively well known thanks to their very good preservation, from the Chengjiang fauna in China and Burgess Shale in Canada, where even sponges with unfused spicules occur. The majority of palaeontologic studies are concerned with taxonomic aspects of fossil sponge faunas, but investigations of the microstructure of the calcareous skeleton, of phylogeny (especially of the early forms), and of various aspects of their ecology have produced important results. Future research still has to fill gaps in the knowledge of fossil faunas, especially "soft" sponges, and in the phylogeny of sponges (especially for the polyphyletic groups like lithistids), but new approaches such as studies of biomarkers are already emerging.
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Ou, Qiang, Jean Vannier, Xianfeng Yang, Ailin Chen, Huijuan Mai, Degan Shu, Jian Han, Dongjing Fu, Rong Wang, and Georg Mayer. "Evolutionary trade-off in reproduction of Cambrian arthropods." Science Advances 6, no. 18 (April 29, 2020): eaaz3376. http://dx.doi.org/10.1126/sciadv.aaz3376.
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Trade-offs play a crucial role in the evolution of life-history strategies of extant organisms by shaping traits such as growth pattern, reproductive investment, and lifespan. One important trade-off is between offspring number and energy (nutrition, parental care, etc.) allocated to individual offspring. Exceptional Cambrian fossils allowed us to trace the earliest evidence of trade-offs in arthropod reproduction. †Chuandianella ovata, from the early Cambrian Chengjiang biota of China, brooded numerous (≤100 per clutch), small (Ø, ~0.5 mm) eggs under carapace flaps. The closely related †Waptia fieldensis, from the middle Cambrian Burgess Shale of Canada, also brooded young, but carried fewer (≤ 26 per clutch), larger (Ø, ~2.0 mm) eggs. The notable differences in clutch/egg sizes between these two species suggest an evolutionary trade-off between quantity and quality of offspring. The shift toward fewer, larger eggs might be an adaptive response to marine ecosystem changes through the early-middle Cambrian. We hypothesize that reproductive trade-offs might have facilitated the evolutionary success of early arthropods.
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Harvey, Thomas H. P. "Carbonaceous preservation of Cambrian hexactinellid sponge spicules." Biology Letters 6, no. 6 (June 16, 2010): 834–37. http://dx.doi.org/10.1098/rsbl.2010.0377.
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Early fossil sponges offer a direct window onto the evolutionary emergence of animals, but insights are limited by the paucity of characters preserved in the conventional fossil record. Here, a new preservational mode for sponge spicules is reported from the lower Cambrian Forteau Formation (Newfoundland, Canada), prompting a re-examination of proposed homologies and sponge inter-relationships. The spicules occur as wholly carbonaceous films, and are interpreted as the remains of robust organic spicule sheaths. Comparable sheaths are restricted among living taxa to calcarean sponges, although the symmetries of the fossil spicules are characteristic of hexactinellid sponges. A similar extinct character combination has been documented in the Burgess Shale fossil Eiffelia . Interpreting the shared characters as homologous implies complex patterns of spicule evolution, but an alternative interpretation as convergent autapomorphies is more parsimonious. In light of the mutually exclusive distributions of these same characters among the crown groups, this result suggests that sponges exhibited an early episode of disparity expansion followed by comparatively constrained evolution, a pattern shared with many other metazoans but obscured by the conventional fossil record of sponges.
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Peel, J. S., S. C. Morris, and J. R. Ineson. "A second glimpse of Early Cambrian life: new collections from Sirius Passet, North Greenland." Rapport Grønlands Geologiske Undersøgelse 155 (January 1, 1992): 48–50. http://dx.doi.org/10.34194/rapggu.v155.8180.
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The German mining term lagerstatten, referring to a rock of any composition containing constituents of economic interest, has been widely applied to occurrences of abundant or unusually well preserved fossils (cf. Seilacher et al., 1985). The Middle Cambrian Burgess Shale of western Canada is perhaps the most famous of all fossil-lagerstatt, with many of the approximately 140 known species preserving exquisite details of the soft anatomy of members of a community of organisms that was fossilised more than 500 million years ago (Whittington, 1985: Conway Morris, 1979, 1986; Gould, 1989). Other well known examples include the Upper Cambrian 'Orsten' of southern Sweden, the Lower Devonian Hunsruck Slate and the Jurassic Solnhofen Limestone of Germany (Stürmer et al.. 1980; Muller, 1985; Barthel et al. 1990; summary in Briggs & Crowther, 1990, pp. 266–297). The term can be applied aptly to the Sirius Passet fauna of central North Greenland, where a wealth of exceptionally preserved fossils (e.g. Fig. 1) from tile Lower Cambrian Buen Formation has been recorded from a small locality in western Peary Land, near the south-western end of the broad valley known as Sirius Passet (Fig. 2). The locality yielding the Sirius
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Caron, Jean-Bernard, David M. Rudkin, and Stuart Milliken. "A new Late Silurian (Pridolian) naraoiid (Euarthropoda: Nektaspida) from the Bertie Formation of southern Ontario, Canada—delayed fallout from the Cambrian explosion." Journal of Paleontology 78, no. 6 (November 2004): 1138–45. http://dx.doi.org/10.1017/s0022336000043948.
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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.
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Collom, C. J., P. A. Johnston, and W. G. Powell. "Reinterpretation of ‘Middle’ Cambrian stratigraphy of the rifted western Laurentian margin: Burgess Shale Formation and contiguous units (Sauk II megasequence), Rocky Mountains, Canada." Palaeogeography, Palaeoclimatology, Palaeoecology 277, no. 1-2 (June 2009): 63–85. http://dx.doi.org/10.1016/j.palaeo.2009.02.012.
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Peel, John S., Simon Conway Morris, and Jon R. Ineson. "The Sirius Passet Fauna, an Early Cambrian Lagerstätte from North Greenland." Paleontological Society Special Publications 6 (1992): 233. http://dx.doi.org/10.1017/s2475262200007930.
Full textAbstract:
The Sirius Passet Fauna of North Greenland is one of the oldest Cambrian lagerstätten from the North American continent. It is known from a single locality in Peary Land (83°N, 40°W), on the shores of the Arctic Ocean, where outer shelf mudstones from the lower part of the Buen Formation (Early Cambrian) yield a rich assemblage of mainly poorly skeletised organisms with preserved soft parts. The steeply-dipping fossiliferous mudstones occur in close proximity to horizontally-bedded platform carbonates of the underlying Portfjeld Formation (Early Cambrian) in a structurally complex terrane. The boundary between the fossiliferous mudstones and the platform carbonates apparently defines the original northern margin of the carbonate platform and is not, as previously suggested, a structural feature, although some minor tectonic modification can not be excluded. Thus, the fossiliferous mudstones were apparently deposited in a transitional slope setting basinward of the shelf edge.As currently known, the Sirius Passet Fauna comprises about 40 species, based on a collection of almost 5,000 slabs collected during brief visits to the isolated locality in 1989 and 1991. Arthropods dominate, with bivalved bradoriids and the trilobite Buenellus higginsi Blaker, 1988 being the numerically most abundant taxa. Weakly skeletised Naraoia-like and Sidneyia-like arthropods often preserve limbs and gills, as do bivalved arthropods similar to Waptia. Choia is the most common of several sponges. Worms include both priapulids and polychaetes, with a large palaeoscolecidan being conspicuous.Fully articulated specimens of halkieriid worms, clad in an armour of hundreds of individual sclerites, are most notable amongst several problematic taxa. Rare specimens of possible onychophorans are also present, while brachiopods, hyoliths and other shelly fossils are rare or absent.The Sirius Passet Fauna seems to show little taxonomic similarity to the Middle Cambrian Burgess Shale of western Canada or the Chengjiang Fauna from the Lower Cambrian of China at the generic level. Together with the latter fauna, however, it confirms both the general picture of Cambrian life presented by the Burgess Shale, and the existence of this great diversity of weakly skeletised arthropods already in the Early Cambrian.
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Anderson, Ross P., Nicholas J. Tosca, Gianfelice Cinque, Mark D. Frogley, Ioannis Lekkas, Austin Akey, Gareth M. Hughes, Kristin D. Bergmann, Andrew H. Knoll, and Derek E. G. Briggs. "Aluminosilicate haloes preserve complex life approximately 800 million years ago." Interface Focus 10, no. 4 (June 12, 2020): 20200011. http://dx.doi.org/10.1098/rsfs.2020.0011.
Full textAbstract:
Mudstone-hosted microfossils are a major component of the Proterozoic fossil record, particularly dominating the record of early eukaryotic life. Early organisms possessed no biomineralized parts to resist decay and controls on their fossilization in mudstones are poorly understood. Consequently, the Proterozoic fossil record is compromised—we do not know whether changing temporal/spatial patterns of microfossil occurrences reflect evolution or the distribution of favourable fossilization conditions. We investigated fossilization within the approximately 1000 Ma Lakhanda Group (Russia) and the approximately 800 Ma Svanbergfjellet and Wynniatt formations (Svalbard and Arctic Canada). Vertical sections of microfossils and surrounding matrices were extracted from thin sections by focused ion beam milling. Elemental mapping and synchrotron-based infrared microspectroscopy revealed that microfossils are surrounded by haloes rich in aluminium, probably hosted in kaolinite. Kaolinite has been implicated in Cambrian Burgess Shale-type (BST) fossilization and is known to slow the growth of degraders. The Neoproterozoic mudstone microfossil record may be biased to tropical settings conducive to kaolinite formation. These deposits lack metazoan fossils even though they share fossilization conditions with younger BST deposits that are capable of preserving non-mineralizing metazoans. Thus metazoans, at least those typically preserved in BST deposits, were probably absent from sedimentary environments before approximately 800 Ma.