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The Fossils


The Burgess Shale is famous for its exquisite fossils of soft-bodied organisms. It is exceptional to find complete animals preserved, especially ones that had only soft tissues and no mineralized structures. (Typically it is only the hard parts of organisms - shell or bone - that become fossils.) When this happens (taphonomy section) palaeontologists can gain a tremendous amount of ecological and biological information about a particular time in Earth's history. The Burgess Shale is such a site, providing the best window on animal communities during the end of the Cambrian Explosion.

This section briefly introduces the fossils of the Burgess Shale and their significance for evolutionary and palaeoecological studies. Most of the species from the Burgess Shale and nearby localities are illustrated in the Fossil Gallery. Additional species have still to be restudied in detail or even described for the first time - these will be added in subsequent updates to this website.

The Walcott Quarry Community

The best-known Burgess Shale site is the Walcott Quarry on Fossil Ridge. About 150 species of animals, algae, and bacteria from here have been described to date. The mammoth collections available to researchers - about 65,000 specimens at the Smithsonian Institution in Washington D.C., 10,000 at the Geological Survey of Canada in Ottawa, and 150,000 specimens at the Royal Ontario Museum in Toronto - form the basis for detailed studies of individual species. These collections allow researchers to study the overall ecosystem using quantitative statistical methods in ways that are not yet possible for other Burgess Shale-type deposits, which lack sufficient fossils.

Parks Canada workers look at dozens of cloth fossil bags

Checking bags of fossils at the end of the 2000 Royal Ontario Museum Field Expedition in Field, BC.

© Royal Ontario Museum. Photo: Jean-Bernard Caron.

Most of the fossils from the Walcott Quarry represent organisms that probably lived in comparatively deep waters at the foot of the Cathedral Escarpment. It had been thought the organisms came from shallower waters on top of the Escarpment, but recent research has suggested most of the animals lived and died where they were buried, at the Escarpment's base.

The Walcott Quarry community is representative of a typical Burgess Shale-type community during the Cambrian. It is estimated that up to 98% of the fossils from this locality are entirely soft-bodied and would stand no chance of being preserved through normal taphonomic processes. The remainder (2%) is represented by animals with parts that were originally mineralized (such as trilobites) and thus can usually fossilize more readily. Trilobites and other "shelly" fossils are found in most typical Cambrian marine deposits around the world. The absence of soft-bodied fossils from those deposits reflects the non-preservation of organisms without hard parts, rather than their absence from the original ecosystem.

A colour representation of a vibrant ecosystem

Reconstruction of the Burgess Shale community (as seen in the Walcott Quarry). The reconstruction below shows how the community would look if only animals with mineralized parts were present.

© Marianne Collins.

General Composition

The composition of the Walcott Quarry community has been extensively studied based on fossil counts made from existing collections. The pie-charts below are derived from a subset of 50,282 specimens collected by the most recent Royal Ontario Museum field expeditions in the Walcott Quarry (the relative abundances of specimens provided in the fossil gallery are based on this number). These represent the relative abundance of specimens and the relative abundance of species within main groups of organisms (or taxa).

The relative abundance of specimens is simply the number of fossils of a particular taxon as a percentage of the total number of fossils collected. The relative abundance of species is the number of species of a particular taxon as a percentage of the total number of species combined. A single taxon might have many species, but be represented by very few specimens. Conversely, one taxon might contain just a few species, but many individual fossil specimens. By comparing the two kinds of pie-charts, palaeoecologists can study patterns of species associations.

The exact affinity of many fossils from the Walcott Quarry is still unknown. However, a large number of species can be linked (as primitive or ancestral forms) to broad groups of organisms that are still known today (see Evolutionary Significance below, and stem group, crown group concepts).

In terms of both number of species and number of specimens, animals make up the majority of the community; a few species of green and red algae, as well as some microbial colonies, are also known. The more important groups by far are the moulting animals with jointed limbs (the arthropods) and the sponges (the poriferans). Most other groups are represented by fewer specimens and species.

A pie chart showing the most-common fossils A chart showing the most abundant species

In order to understand the ecological structure of the Walcott Quarry community, it is important to determine where and how each kind of organism lived.

In the Walcott Quarry, most species represent benthic forms - animals living in or near the sea bed. Benthic animals can be infaunal (living within the sea-floor sediment), epifaunal (living on the sea-floor surface) or nektobenthic (swimming close to the sea floor).

A small minority of animals did not interact with the sea floor, living entirely in the water column as pelagic (swimming) forms.

Burgess Shale animals can also be categorized based on their mobility. Nektobenthic and nektonic organisms were active swimmers. Planktonic creatures mostly drifted passively rather than actively swimming. Some of the infaunal and epifaunal benthic organisms were sessile (fixed in one place) while others were mobile (able to move around).

Slab of rock showing fossils of many star-like sponges

A cluster of the sessile benthic sponge Choia ridleyi from the Burgess Shale (size = 7.8 cm).

© Smithsonian Institution - National Museum of Natural History. Photo: Jean-Bernard Caron.

Finally, Burgess Shale animals can be categorized on the basis of how they obtained their food. Suspension feeders filtered particles of food out of the water. Deposit feeders gathered particles of food that settled on or in the sea floor sediment layer. Carnivorous hunters actively captured and devoured other animals, and scavengers took advantage of any dead bodies they came across. Grazers lived by munching on photosynthetic algae or cyanobacteria that grew in the dim sunlight that penetrated to the base of the Escarpment.

Palaeontologists can recreate the proportions of species in the Burgess ecosystem falling into each of these categories. The overwhelming majority of species (64%) were epifaunal, living on the sea bed (most notably the sponges), followed by the infaunal sediment-dwellers (13%) and the low-level swimming nektobenthics (12%). Swimming nektonic species were the least common (11%).

Chart showing the frequency of different lifestyles

Food Web

A food web reconstructs the feeding relationships between different organisms in a community.

In the Burgess Shale, the ecosystem ultimately relied on photosynthetic algae and bacteria, which used energy absorbed from sunlight in order to grow. Other organisms fed (directly or indirectly) either on algae and bacteria growing on the sea floor or on planktonic forms that sank from the waters above (see reconstruction of the Burgess Shale community above).

Animals living in or on the sea floor could filter food particles out of the water, scrounge for fragments of food on the muddy bottom, or graze directly on the algal or bacterial mats. Comparatively few animals made a living by active hunting or scavenging, but their impact on the food web would have been great.

The structure of the Burgess Shale ecosystem food web is surprisingly similar to what we see in modern marine communities, although the individual species involved are clearly quite different. This suggests that the basic feeding relationships were quickly established during the Cambrian Explosion and have remained relatively unchanged to the present.

Graphic showing relationships between different Burgess Shale organisms

Reconstruction of the Burgess Shale food web. Spheres represent taxa. The taxa at the bottom of this network are primary producers and the taxa at the top are predators. (modified from Dunne et al).

Palaeontologists can use a variety of clues to reconstruct the diets of Burgess Shale animals. Occasionally feces, or even gut contents, are fossilized, the latter providing a direct record of an animal's final meal.

Fossil of a worm, showing gut contents Bottom left, fossil showing guts standing out in relief; Right, guts in more detail

Gut contents in Burgess Shale animals. Top, detail of the gut of Ottoia prolifica (maximum width of the worm = 1.2 cm) showing shelly, conic elements of Haplophrentis carinatus. Below, a specimen of the arthropod Sidneyia inexpectans (length = 8 cm), showing fragments of small trilobites in the gut suggesting a predatory (or scavenging) lifestyle (see close up of the gut on the right).

© Royal Ontario Museum. Photos: Jean-Bernard Caron.

Usually, dietary habits have to be inferred from the ecological niche an animal occupied and from specialized body structures used in feeding. Anomalocaris, for example, had large eyes, grasping limbs, swimming lobes, and tooth-like mouthparts. Together with its large size, these features strongly suggest Anomalocaris was a predator.

Large fossil detailing specialized body structures like large eyes, grasping limbs, swimming lobes, and tooth-like mouthparts, suggesting it was a predator.

Front part of Anomalocaris canadensis, a putative predator from the Burgess Shale (size = 16.6 cm).

© Royal Ontario Museum. Photo: Jean-Bernard Caron.

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Evolutionary Significance

The nature of the animals in the Burgess Shale biota, and their evolutionary significance, have been topics of particular interest since the discovery of the first fossils over a hundred years ago. Interpretations have changed over time, but it is clear these fossils are vital to understand how life shaped itself during the Cambrian Explosion. Interest in the evolutionary significance of the biota was revived by the discovery of other Burgess Shale-type deposits in various parts of the world and detailed re-examination of fossils from the Burgess Shale itself.

Charles Walcott originally considered the fossils of the Burgess Shale to belong to extinct categories within animal groups that are still alive today. However, many Burgess Shale animals look bizarre to modern eyes, and subsequent detailed descriptions suggested they could not be quite so easily accommodated within the definitions based on modern groups.

This was evidence for some, most notably Stephen Jay Gould that the Cambrian Explosion was a period of experimentation, with far more body plans in the Cambrian than today (thus representing greater evolutionary disparity). By chance, only some of these body plans survived to represent the phyla that we know today. If Gould was right, and the strange creatures of the Burgess Shale - referred to by Gould as "weird wonders"- truly represent lost phyla, the range of evolutionary innovations during the Cambrian Explosion would be far greater than previously thought.

Fossil showing possible origins of modern animals

More recent observations suggest the number of body plans in the Cambrian was probably no greater than in modern environments. Many of Gould's "weird wonders" have now been re-accommodated within living animal phyla, albeit at some distance from modern groups within those phyla.

A number of bizarre forms remain difficult to classify. Part of the problem is that some of these are still poorly known - i.e., there is not enough well-preserved fossil material to describe the anatomy of the animals with certainty. Other, better-known fossils display only some of the traits associated with known groups, or possess a combination of traits that remains at odds with what we know for any living or extinct organisms. These are now interpreted as primitive animals which evolved along the lineages of established phyla or groups of phyla (see crown-group and stem-group).

Some of the most recent changes in interpretation are based on new fossil material that provides many more specimens and traits to study. A number of previously "unclassifiable" fossils (for example Odontogriphus and Nectocaris) had been known from single, poorly-preserved specimens. Hundreds of new specimens are helping to explain the nature and evolutionary significance of these animals. The use of computers (i.e., parsimony analysis) to classify organisms, and the use of the stem group and crown-group concepts, also contributed to this change. Evolutionary relationships are identified by recognizing traits that different organisms share by inheritance.

Left, black and white bean-shaped fossil ; Right, a fossil of a more complex organism, with a distinct head with antennae-like structures, and villi around its body.  Drawings of what fossils may have looked like and modern reconstruction of organisms

Changing reconstructions of two "weird wonders" from the Burgess Shale, Odontogriphus (left, fossil length = 8 cm) and Nectocaris (right, fossil length = 4 cm, excluding tentacles), both now considered to belong to stem-groups within the molluscs.

© Marianne Collins (drawings) and Royal Ontario Museum (fossils). Photos: Jean-Bernard Caron.

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Ecological Significance

The Burgess Shale provides direct fossil evidence of the emergence of a number of animal groups in marine environments that had been mostly unoccupied before the Cambrian Explosion. This evolutionary radiation happened at the same time as a sudden increase in ecosystem complexity, marked by the appearance of new types of species interactions driven by ecological innovations - such as novel feeding strategies and modes of locomotion. At the end of the Cambrian Explosion, the fundamental ecological structures of modern marine ecosystems were firmly in place.

Among the various feeding strategies that are known in the Burgess Shale - predation (including scavenging), herbivory, and detritus and suspension feeding - predation is regarded as one of the most significant. Predators play an important role in structuring modern communities by controlling prey populations. Predation was likely an important driving force for the diversification seen in the Cambrian Explosion, as animals evolved new strategies to eat and avoid being eaten.

A number of possible Burgess Shale predators have been identified based on direct morphological characters (the mouth parts of Anomalocaris) and on gut contents. Indirect evidence such as potential bite marks and defensive features (such as spines in Hallucigenia or plate-like elements in Wiwaxia) have also been identified. The development of mineralized skeletons at the start of the Cambrian Explosion is also thought to have been a response to increased pressure from predators.

Top, fossil with large spines; Bottom, fossil with plates and sharp hooks

The lobopod animal Hallucigenia (top, size = 2 cm) and the armoured slug-like animal Wiwaxia (bottom, size = 3 cm). Hallucigenia possesses rows of spines on the back of its body while Wiwaxia developed a body armour of small, overlapping scales and blades. Both traits may have evolved as a defensive mechanism against predators.

© Smithsonian Institution - National Museum of Natural History (top); © Royal Ontario Museum (bottom). Photos: Jean-Bernard Caron.

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Fossils from the Walcott Quarry

Some groups have more species and specimens than others. Below is a detailed breakdown of the species from the Walcott Quarry belonging to these main groups. Species with mineralized parts are emphasized in bold - these are the only ones that could have been fossilized under normal conditions, rather than the special conditions leading to Burgess Shale-type preservation. Details and illustrations of most species listed below are illustrated in the Fossil Gallery.

Algae and bacteria

Algae: This group consists of eukaryotic organisms that usually depend on light as their source of energy. In the Walcott Quarry, both green and red algae have been identified, but many species are probably just preservational or morphological variants of a small number of taxa. Most have yet to be studied in any detail.

12 species: Bosworthia gyges, Bosworthia simulans, Dalyia nitens, Dalyia racemata, Dictyophycus gracilis, Margaretia dorus, Sphaerocodium? cambria, Sphaerocodium? praecursor, Wahpia mimica, Wahpia virgata, Waputikia ramosa, Yuknessia simplex.

Margaretia dorus

Margaretia dorus.

© Smithsonian Institution - National Museum of Natural History. Photo: Jean-Bernard Caron.

Cyanobacteria: This is a group of prokaryotic microorganisms that depend on light for their source of energy. In the Walcott Quarry, there are at least two different species, one forming tufts (Marpolia), the other forming sheet-like structures at the sea bottom (Morania). Walcott briefly described 8 species of Morania, but as is the case with the algae, many of these are probably just preservational variants and have yet to be restudied in detail.

9 species: Marpolia spissa, Morania confluens, Morania elongata, Morania fragmenta, Morania? frondosa, Morania? globosa, Morania parasitica, Morania? reticulata.

Marpolia spissa

Marpolia spissa.

© Royal Ontario Museum. Photo: Jean-Bernard Caron.

Animals

Annelida: These elongated, many-segmented animals are represented today by the common terrestrial earthworms and leeches, marine-swimming animals ("polychaetes") including bristle worms, and several smaller groups. The annelid body is covered by a thin flexible cuticle that is not moulted during growth. Each major group has a characteristic segment construction; in annelid bristle worms, segments bear a prominent pair of lateral flap-like structures called parapodia that are mainly used for locomotion. Various numbers of "bristles" (chaetae) are organized in bundles along the parapodia and help with movement. Many fossil annelids from the Burgess Shale show exquisite preservation of parapodia and bristles. Based on the morphology of these elements, some were interpreted as active swimmers (e.g., Canadia), while others probably lived in or on the mud at the bottom of the sea (e.g., Peronochaeta). These Burgess Shale taxa are not currently thought to belong to the modern forms of bristle worms, and have most recently been reinterpreted as stem group annelids.

5 species: Burgessochaeta setigera, Canadia spinosa, Insolicorypha psygma, Peronochaeta dubia, Stephenoscolex argutus.

Canadia spinosa

Canadia spinosa.

© Smithsonian Institution - National Museum of Natural History. Photo: Jean-Bernard Caron.

Arthropoda: Today, arthropods are the most diverse of all animal groups, a distinction they have probably held since the Cambrian. Characterized by a segmented body, a rigid external cuticular covering (the exoskeleton), and jointed limbs, this group is represented by the modern spiders, shrimps, insects, and millipedes. It also includes the now-extinct trilobites. Arthropods grow by shedding their exoskeleton (a process called moulting), which can harden or even mineralize in some cases (such as in crabs and trilobites). The Burgess Shale contains a wide range of fossil arthropod morphologies, many representing various stem groups of particular subgroups within the arthropods. Others, for example Opabinia and Anomalocaris, are considered more primitive and cannot be considered true arthropods (Euarthropoda). These species might represent early stem groups along the lineage leading to true arthropods. Fossil arthropods found in the Walcott Quarry show adaptation to a wide range of habitats and ecologies; they include carnivores and deposit feeders, swimmers, walkers, and probably burrowers.

53 species: Alalcomenaeus cambricus, Anomalocaris canadensis, Branchiocaris pretiosa, Burgessia bella, Canadaspis perfecta, Caryosyntrips serratus, Chancia palliseri, Ehmaniella burgessensis, Ehmaniella waptaensis, Elrathia permulta, Elrathina cordillerae, Emeraldella brocki, Habelia brevicauda, Habelia optata, Hanburia gloriosa, Helmetia expansa, Houghtonites gracilis, Hurdia victoria, Isoxys acutangulus, Isoxys longissimus, Kootenia burgessensis, Laggania cambrica, Leanchoilia persephone, Leanchoilia protogonia, Leanchoilia superlata, Liangshanella burgessensis, Marrella splendens, Molaria spinifera, Mollisonia rara, Mollisonia symmetrica, Naraoia compacta, Naraoia spinifer, Odaraia alata, Olenoides serratus, Opabinia regalis, Oryctocephalus burgessensis, Oryctocephalus matthewi, Pagetia bootes, Perspicaris dictynna, Perspicaris recondita, Plenocaris plena, Priscansermarinus barnetti, Ptychagnostus praecurrens, Sarotrocercus oblita, Sidneyia inexpectans, Skania fragilis, Tegopelte gigas, Thelxiope palaeothallasia, Tuzoia retifera, Tuzoia burgessensis, Waptia fieldensis, Worthenenella crepidulus, Yohoia tenuis.

Naraoia compacta

Naraoia compacta.

© Smithsonian Institution - National Museum of Natural History. Photo: Jean-Bernard Caron.

Brachiopoda: Brachiopods are bottom-dwelling (benthic) marine suspension-feeding animals enclosed in a two-part shell. Most forms attach to a surface - the sea floor or other organisms - via a flexible cylindrical organ called a pedicle. Brachiopods first appeared in the Early Cambrian and were very important constituents of the sea-floor ecosystem throughout the Palaeozoic Era. Although some species still survive, the phylum was hit hard by the Late Permian mass extinction (about 250 million years ago). Most brachiopod shells are well-mineralized, and they consequently have a good fossil record. In the Burgess Shale, some stem group forms are preserved with soft-tissues, including their pedicles, setae (long, needle-like structures) and traces of the internal body organs. One Burgess Shale species (Acanthrotretella spinosa) has non-mineralized valves.

7 species: Acanthrotretella spinosa, Acrothyra gregaria, Diraphora bellicostata, Lingulella waptaensis, Micromitra burgessensis, Nisusia burgessensis, Paterina zenobia.

Micromitra burgessensis

Micromitra burgessensis.

© Smithsonian Institution - National Museum of Natural History. Photo: Jean-Bernard Caron.

Chordata: Chordates are a group of animals united by the possession of a notochord and a dorsal nerve cord. In addition to the vertebrates (including humans) with their defining backbone and spinal column, chordate subgroups also include a number of minor taxa. Some chordates are attached to a surface - usually the sea floor - for at least part of their life, but most are mobile organisms. Pikaia gracilens from the Burgess Shale probably represents a very primitive (stem-group) form of chordates. Well-preserved fossils indicate it was an active swimmer. A second Burgess Shale stem-group chordate species is known only from two poorly preserved specimens.

2 species: Metaspriggina walcotti, Pikaia gracilens.

Pikaia gracilens

Pikaia gracilens.

© Smithsonian Institution - National Museum of Natural History. Photo: Jean-Bernard Caron.

Cnidaria: These radially-symmetrical animals have a simple body organization and two basic life modes: the swimming, jellyfish-like medusae, and sessile, polyp-like forms. The group includes modern corals and jellyfish. Various tubular fossils from the Walcott Quarry have been attributed to primitive sessile cnidarians, but until better details of their soft-tissue structures are found, such conclusions will remain provisional. Mackenzia is the only form not to have inhabited a tube; this soft-bodied, seabed-dwelling animal has been compared to living sea anemones.

4 species: Cambrorhytium fragilis, Cambrorhytium major, Mackenzia costalis, Tubullela flagellum.

Cambrorhytium fragilis

Cambrorhytium fragilis.

© Smithsonian Institution - National Museum of Natural History. Photo: Jean-Bernard Caron.

Ctenophora: Ctenophores are radially organized animals with a simple body plan superficially resembling that of cnidarian jellyfish. Living representatives of this group are termed "comb jellies" because they have 8 comb-like rows of cilia (cilia are small elongated extensions of cells which can reach up to 2 millimetres in modern ctenophores) to propel them through the water. The fossil species from the Walcott Quarry have more comb rows than modern ctenophores and probably represent very primitive (stem-group) forms.

2 species: Ctenorhabdotus capulus, Fasciculus vesanus.

Ctenorhabdotus capulus

Ctenorhabdotus capulus.

© Royal Ontario Museum. Photo: Jean-Bernard Caron.

Echinodermata: The echinoderms form a distinctive group of mostly benthic animals (living in, on or just above the sea floor). They are characterized by a multi-element mineralized skeleton with a peculiar microstructure (stereom). Almost all adult echinoderms exhibit fivefold (pentameral) symmetry (i.e., the body is organized into five radially similar sections). Living subgroups include the sea stars, sea urchins, and sea lilies (crinoids). Only stem-group echinoderms are found in the Burgess Shale, where they are relatively rare.

4 species: Echmatocrinus brachiatus, Gogia stephenensis, Walcottidiscus typicalis, Lyracystis reesei.

Echmatocrinus brachiatus

Echmatocrinus brachiatus.

© Geological Survey of Canada. Photo: Jean-Bernard Caron.

Hemichordata: Hemichordates are a group of elongate animals with bodies composed of three main parts: a proboscis (mouthpart), collar, and trunk. Two major sub-groups are known, the worm-like enteropneusts and the diminutive and colonial pterobranchs. Primitive members of both groups are probably represented in the Walcott Quarry, but these species have not yet been described in detail.

3 species: Chaunograptus scandens, Oesia disjuncta, "Ottoia tenuis".

Chaunograptus scandens

Chaunograptus scandens.

© Smithsonian Institution - National Museum of Natural History. Photo: Jean-Bernard Caron.

Mollusca: A large group of animals, today characterized by a cavity-forming mantle. Modern molluscs include snails, squids, and clams. Fossils of several swimming and bottom-dwelling soft-bodied forms are known in the Walcott Quarry - these are considered to be basal stem-groups molluscs. Scenella is the only form with a mineralized shell.

5 species: Nectocaris pteryx, Odontogriphus omalus, Orthrozanclus reburrus, Scenella amii, Wiwaxia corrugata.

Odontogriphus omalus

Odontogriphus omalus.

© Royal Ontario Museum. Photo: Jean-Bernard Caron.

Onychophora (Lobopoda): Worm-like animals with unspecialized pairs of non-jointed limbs, the modern onychophorans (velvet worms) are all terrestrial. The two fossil species known in the Walcott Quarry are not true onychophorans, but probably belong within the lobopods, a stem-group of organisms more closely related to arthropods.

2 species: Aysheaia pedunculata, Hallucigenia sparsa.

Aysheaia pedunculata

Aysheaia pedunculata.

© Smithsonian Institution - National Museum of Natural History. Photo: Jean-Bernard Caron.

Porifera: The Porifera (or sponges) are among the most primitive animals; their simple body is not organized into true tissues. Sponges are mostly bottom-dwelling suspension feeders, and many forms possess a supporting mesh-work of fine needle-like spicules composed of various minerals. Several different types of fossil sponges are found in the Walcott Quarry, representing all major modern groups as well as potential stem-groups. Many of these have a low preservation potential, but isolated mineralized spicules of some taxa (in bold) are known in other Cambrian fossil deposits that do not preserve soft-tissues.

34 species: Capsospongia undulata, Choia carteri, Choia ridleyi, Crumillospongia biporosa, Crumillospongia frondosa, Diagoniella cyathiformis, Diagoniella hindei, Eiffelia globosa, Falospongia falata, Halicondrites elissa, Hamptonia bowerbanki, Hazelia conferta, Hazelia crateria, Hazelia delicatula, Hazelia dignata, Hazelia lobata, Hazelia luteria, Hazelia nodulifera, Hazelia obscura, Hazelia palmata, Leptomitus lineatus, Leptomitus undulatus, Moleculospina mammilata, Petaloptyon danei, Pirania muricata, Protospongia hicksi, Takakkawia lineata, Vauxia bellula, Vauxia densa, Vauxia irregulara, Vauxia gracilenta, Vauxia venata, Wapkia elongata, Wapkia grandis.

Choia ridleyi

Choia ridleyi.

© Smithsonian Institution - National Museum of Natural History. Photo: Jean-Bernard Caron.

Priapulida: Predatory marine worms with a large, hook-lined anterior feeding organ called a proboscis, priapulids are relatively rare today. Priapulid-like animals were abundant in Cambrian communities; species found in the Walcott Quarry, including tube-dwelling forms, are probably stem-group priapulids.

5 species: Ancalagon minor, Fieldia lanceolata, Louisella pedunculata, Ottoia prolifica, Selkirkia columbia.

Selkirkia columbia

Selkirkia columbia.

© Geological Survey of Canada. Photo: Jean-Bernard Caron.

Other known animals of uncertain affinities:

10 species: Allonnia sp., Amiskwia sagittiformis, Chancelloria eros, Dinomischus sagittiformis, Eldonia ludwigi, Haplophrentis carinatus, Herpetogaster collinsi, Pollingeria grandis, Portalia mira, Thaumaptilon walcotti.

Portalia mira

Portalia mira.

© Smithsonian Institution - National Museum of Natural History. Photo: Jean-Bernard Caron.

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