The Burgess Shale

Yawunik kootenayi

Yawunik kootenayi, ROMIP 64017

Taxonomy:

Kingdom: Very abundant
Phylum: Very abundant
Higher Taxonomic assignment: Megacheirans, Family Leanchoiliidae
Species name: Yawunik kootenayi
Remarks:

Yawunik is a representative of the megacheiran family Leanchoiliidae (Aria, Caron, & Gaines, 2015). Megacheirans are basal true arthropods with a frontal appendage pointing upward and made of multiple claws (the cheira, or “great appendage”). Megacheirans are generally considered to be among the first true arthropods (that is, arthropods with segmented bodies and appendages), and possibly the earliest representatives of the extended chelicerate lineage (Aria, 2022).

Described by: Aria, Caron and Gaines
Description date: 2015
Etymology:

Yawunik – Latinized spelling of Yawu?nik’, the fierce monster of the Ktunaxa First Nation’s creation story.

kootenayi – After the name Kootenay National Park, representing the area where the fossil was found, a territory previously inhabited by the Ktunaxa First Nation among others.

Type Specimens: Holotype ROMIP 62977, at the Royal Ontario Museum, Toronto, Canada
Other species:

Burgess Shale and vicinity: None
Other deposits: None

Age & Localities:

Age:
Middle Cambrian, Wuliuan stage, upper part of the Burgess Shale Formation (around 507 million years old).
Principal localities:

Marble Canyon, Kootenay National Park, British Columbia.

History of Research:

Brief history of research:

Along with Surusicaris elegans (Aria & Caron, 2015), Yawunik kootenayi is one of the first two arthropods described from the Marble Canyon locality of the Burgess Shale (Aria et al., 2015). The original study was based on 42 specimens from the 2012 Royal Ontario Museum expedition, the same year the new fossil deposit was found. Dozens more specimens have since been collected, making Yawunik one of the most abundant arthropods of the Marble Canyon quarry, next to Sidneyia (Nanglu, Caron, & Gaines, 2020). As the largest and one of the best preserved megacheiran arthropod, Yawunik has since been referenced in many studies.

Description:

Morphology:

Yawunik kootenayi was a large predator, stouter than its closest relatives. The body lacks any biomineralization. Like other leanchoiliid megacheirans, it is characterized by flagellate frontal appendages (cheirae) made of three long claws, and a body divided into two regions (tagmata): the cephalon, covered by a single shield, and the segmented trunk. At the front of the head, leanchoiliids bore a pair of large unstalked lateral eyes and a pair of smaller, mushroom-shaped median eyes. The megacheiran appendages were of similar simple morphology throughout the body, reflecting the typical arthropod biramous limb: sub-cylindrical basis with teeth for mastication (basipod), relatively strong walking legs (endopods), and paddle-like, semi-rigid flaps (exopods) fringed with lamellae. The tail is a single element called a telson, having the shape of spear’s tip (lanceolate).

Abundance:

Known through more than 180 specimens, Yawunik is one of the most abundant arthropods of Marble Canyon, and is also known from Tokumm Creek.

Maximum Size:
About 20 cm.

Ecology:

Life habits: Very abundant
Feeding strategies: Very abundant
Ecological Interpretations:

Like other leanchoiliid megacheirans the frontal appendages of Yawunik likely combined both sensing and grasping functions to detect and catch prey items. Food caught was brought under the body where it was rudimentarily masticated between the bases of limbs (basipods), before being channeled back to the mouth. As a leanchoiliid, Yawunik also had large glands atop its gut, presumably involved in digestion. The megacheiran body appendages, made of relatively strong walking legs (endopods) as well as paddle-like, semi-rigid flaps (exopods), would have allowed for both locomotion on the sea floor and swimming. The exopods likely served for gas exchanges (like breathing) as well, but recent studies showed that megacheirans and other Cambrian arthropods also possessed dedicated gills (Liu et al., 2021).

References:

  • Aria, C. & Caron, J.-B. (2015) Cephalic and limb anatomy of a new isoxyid from the Burgess Shale and the role of ‘stem bivalved arthropods’ in the disparity of the frontalmost appendage. PLoS ONE 10, e0124979.
  • Aria, C., Caron, J.-B. & Gaines, R. (2015) A large new leanchoiliid from the Burgess Shale and the influence of inapplicable states on stem arthropod phylogeny. Palaeontology 58, 629–660.
  • Liu, Y., Edgecombe, G.D., Schmidt, M., Bond, A.D., Melzer, R.R., Zhai, D., Mai, H., Zhang, M. & Hou, X. (2021) Exites in Cambrian arthropods and homology of arthropod limb branches. Nature Communications 12, 4619.
  • Nanglu, K., Caron, J.-B. & Gaines, R.R. (2020) The Burgess Shale paleocommunity with new insights from Marble Canyon, British Columbia. Paleobiology 46, 58–81.
Other Links:

Spartobranchus tenuis

Spartobranchus tenuis, ROMIP 65137

Taxonomy:

Kingdom: Very abundant
Phylum: Very abundant
Higher Taxonomic assignment: Enteropneusta
Species name: Spartobranchus tenuis
Remarks:

Spartobranchus is considered a stem-group enteropneust (acorn worm), and shares many similarities with modern acorn worms (Caron et al. 2013; Nanglu et al. 2020). It shows the tripartite body characteristic of this group, consisting of an acorn-shaped proboscis, cylindrical collar, and elongate trunk.

Described by: Walcott
Description date: 1911 (redescribed in 2013)
Etymology:

Spartobranchus — from the Greek “sparte,” for cord or rope (made from the Spartium shrub), and “brankhia” for gills.

tenuis — from the Latin, meaning thin or delicate.

Type Specimens: USNM 108494; Paralectotype – USNM 553526.
Other species:

Burgess Shale and vicinity: None
Other deposits: None

Age & Localities:

Age:
Middle Cambrian, Wuliuan stage, Burgess Shale Formation (around 507 million years old).
Principal localities:

Walcott Quarry

History of Research:

Brief history of research:

Spartobranchus tenuis was first reported by Walcott in 1911 as a priapulid worm named Ottoia tenuis. It was removed from the genus Ottoia by Conway Morris in 1979, and formally redescribed as Spartobranchus tenuis, an acorn worm, by Caron et al. in 2013.

Description:

Morphology:

Spartobanchus is a small worm with a maximum length of 10 cm. The three major components of its body are a proboscis, a collar, and a long, thin section called the trunk. The proboscis is oval or “acorn” shaped, hence the common name of the group: acorn worms. The trunk is a relatively short cylindrical section behind the proboscis. The trunk comprises roughly 90%-95% of the total body length of the animal. The entire body is highly flexible, with the trunk often being recurved onto itself. The anterior part of the trunk is known as the pharynx. Inside the pharynx are presumably collagenous bars known as gill bars, which give the pharynx a strongly striated appearance. The posterior part of the trunk is where the gut is located and is relatively featureless. It is often preserved darkly compared to the rest of the body. At the most posterior end of the trunk is a bulbous structure, which may have served as an anchor for the animal. Roughly one quarter of Spartobranchus specimens are found associated with fibrous, collagenous tubes that the worms produced. These tubes have a corrugated appearance, and can take many forms including: straight tubes, forked, spiral, and circular.

Abundance:

More than 9000 specimens, making it one of the most abundant species in the Walcott Quarry.

Maximum Size:
About 10 cm.

Ecology:

Life habits: Very abundant
Feeding strategies: Very abundant
Ecological Interpretations:

Spartobranchus was likely a deposit feeder, as this is the most common mode of life of extant acorn worms that are morphologically highly similar. The presence of a pre-oral ciliary organ on the proboscis also suggests that food particles were transported from the proboscis to the mouth. It may have also been able to filter feed, given the ability of some burrowing hemichordates to draw in food from interstitial water. The tubes Spartobranchus is associated with would have served as a protective dwelling and were secreted by the proboscis. These worms shared this trait with their close relatives, the graptolites. Some large tubes from the Raymond Quarry (located roughly 20m above the Walcott Quarry) appear to also contain undescribed acorn worms similar in morphology to Spartobranchus (Nanglu and Caron 2021). These tubes also possessed polychaetes, suggesting a symbiotic relationship between these worms.

References:

  • CARON, J.-B., CONWAY MORRIS, S., AND C. B. CAMERON. 2013. Tubicolous enteropneusts from the Cambrian period. Nature 495: 503-506
  • CONWAY MORRIS, S. 1979. The Burgess Shale (Middle Cambrian) fauna. Annual Review of Ecology, Evolution, and Systematics 10: 327–349.
  • NANGLU, K. AND J.-B. CARON. 2021. Symbiosis in the Cambrian: enteropneust tubes from the Burgess Shale co-inhabited by commensal polychaetes. Proceedings of the Royal Society B 288 (1951): 20210061.
  • NANGLU, K., J.-B. CARON, AND C. B. CAMERON. 2020. Cambrian tentaculate worms and the origin of the hemichordate body plan. Current Biology 30 (21): 4238-4244
  • WALCOTT, C. 1911. Cambrian Geology and Paleontology II. Middle Cambrian annelids. Smithsonian Miscellaneous Collections, 57(5): 109-145.
Other Links:

Siphusauctum gregarium

Siphusauctum gregarium, ROMIP 61423

Taxonomy:

Kingdom: Very abundant
Phylum: Very abundant
Higher Taxonomic assignment: None
Species name: Siphusauctum gregarium
Remarks:

Siphusauctum was originally compared to several fossil and living stalked animals, including ctenophores (O’Brien and Caron 2012). Despite some similarities, the authors ultimately rejected any close connections with any living or fossil groups, with the possible exception of Dinomischus, another enigmatic stemmed animal from the Burgess Shale (Conway Morris 1977) and China. More recently, Siphusauctum has been viewed as a possible stem-group ctenophore (Zhao et al. 2019).

Described by: O’Brien and Caron
Description date: 2012
Etymology:

Siphusauctum — from the Latin “siphus,” which means “cup or goblet,” and the Latin “auctus,” meaning large.

gregarium — from the Latin “gregalis,” which means “flock,” referring to large clusters of specimens recovered.

Type Specimens: Holotype ROMIP 61414; paratypes ROMIP 61413, 61415, 61421 in the Royal Ontario Museum, Toronto, Canada
Other species:

Burgess Shale and vicinity: None
Other deposits: Siphusauctum lloydguntheri from the Spence Shale of Utah (Kimmig et al. 2017)

Age & Localities:

Age:
Middle Cambrian, Wuliuan stage, Burgess Shale Formation (around 507 million years old).
Principal localities:

Mount Stephen (Tulip Beds locality), British Columbia.

History of Research:

Brief history of research:

The Tulip Beds (initially known as “locality 8” (Collins et al. 1983) and later as “S7”(Fletcher and Collins 2003)) was discovered in 1983. It is not until a detailed overview of all material collected by ROM-led parties over multiple field seasons that a formal description of this species was published (O’Brien and Caron 2012), followed by a quantitative palaeocological study of the Tulip Beds.

Description:

Morphology:

This animal consists of three parts: a holdfast, a stem and a large calyx-shaped structure. The calyx-shaped structure is the most conspicuous part: it is composed of a continuous external sheath, perforated by the anus on top, and six holes at the bottom, and covers six comb-like internal elements arranged around a large central cavity. The comb-like elements are crescent-shaped, surrounded by a membrane with thin striae. Each comb-like element is composed of two sets of 30 transverse canals (or grooves) radiating on either side of a larger canal positioned abaxially. Following the anus, the body cavity encapsulates a digestive tract, which is composed of a narrow intestine and a wider zone, possibly representing the stomach, at the base of the tract and above a conical zone which connects to the stem. The stem is composed of an internal (inner) and external (outer) element. The inner stem connects directly to a bulbous or flat holdfast. At least one specimen suggests the presence of a tube between the stomach and the inner stem. The outer element ends sharply before the holdfast.

Abundance:

1,133 specimens, making it one of the most abundant species at the Tulip Beds (O’Brien and Caron 2016).

Maximum Size:
About 22 cm high.

Ecology:

Life habits: Very abundant
Feeding strategies: Very abundant
Ecological Interpretations:

The morphology and internal features of this animal strongly suggests it was a facultative stalked animal, living above the seafloor, and was an active filter feeder. The expansion and contraction of the calyx would have allowed the water and nutrients to circulate through the comb-like elements.

References:

  • COLLINS, D., BRIGGS, D. E. G. and CONWAY MORRIS, S. 1983. New Burgess Shale fossil sites reveal Middle Cambrian faunal complex. Science, 222, 163-167.
  • CONWAY MORRIS, S. 1977. A new entoproct-like organism from the Burgess Shale of British Columbia. Palaeontology, 20, 833-845.
  • FLETCHER, T. P. and COLLINS, D. 2003. The Burgess Shale and associated Cambrian formations west of the Fossil Gully Fault Zone on Mount Stephen, British Columbia. Canadian Journal of Earth Sciences, 40, 1823-1838.
  • KIMMIG, J., STROTZ, L. C. and LIEBERMAN, B. S. 2017. The stalked filter feeder Siphusauctum lloydguntheri n. sp. from the middle Cambrian (Series 3, Stage 5) Spence Shale of Utah: its biological affinities and taphonomy. Journal of Paleontology, 91, 902-910.
  • O’BRIEN, L. J. and CARON, J.-B. 2012. A new stalked filter-feeder from the Middle Cambrian Burgess Shale, British Columbia, Canada. PLoS ONE, 7, e29233.
  • O’BRIEN, L. J. and CARON, J.-B. 2016. Paleocommunity Analysis of the Burgess Shale Tulip Beds, Mount Stephen, British Columbia: Comparison with the Walcott Quarry and Implications for Community Variation in the Burgess Shale. Paleobiology, 42, 27-53.
  • ZHAO, Y., VINTHER, J., PARRY, L. A., WEI, F., GREEN, E., PISANI, D., HOU, X., EDGECOMBE, G. D. and CONG, P. 2019. Cambrian sessile, suspension feeding stem-group ctenophores and evolution of the comb jelly body plan. Current Biology, 29, 1112-1125.e2.
Other Links:

Peronopsis columbiensis

Peronopsis columbiensis, cephalon showing appendages ROMIP 64993

Taxonomy:

Kingdom: Very abundant
Phylum: Very abundant
Higher Taxonomic assignment: Artiopoda, Order: Agnostida
Species name: Peronopsis columbiensis
Remarks:

Owing to their distinctive appearance, agnostids have been classified either as trilobites, related to Eodiscina, or as stem group “crustaceans” (Müller and Walossek 1987; Cotton and Fortey 2005; Haug et al. 2009). The most recent phylogenetic analysis finds that agnostids form a grouping with trilobites, supported by shared features of the dorsal exoskeleton, such as mineralization, the expression of segmental boundaries, and the form of the thoracic joints (Moysiuk and Caron 2019). More taxonomically inclusive analyses will be needed to determine whether they belong inside or outside the group of true trilobites.

Described by: Rasetti
Description date: 1951
Etymology:

Peronopsis – From the Greek perone, “pin, brooch ” and opsis, “looking like.”

columbiensis – No etymology provided, but presumably in reference to the occurrence of the species in British Columbia, Canada.

Type Specimens: Holotype – USNM 116267; paratypes – USNM 116268-9; in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: P. montis

Other deposits: other species occur throughout the world in the middle Cambrian.

Age & Localities:

Age:
Middle Cambrian, Wuliuan stage, Burgess Shale Formation (around 507 million years old).
Principal localities:

Mount Stephen, Mount Odaray, Marble Canyon.

History of Research:

Brief history of research:

Burgess Shale material was originally named Peronopsis columbiensis by Rasetti (1951). Naimark (2012) proposed to reassign the species to the genus Quadragnostus based on published images, but we maintain it here under Peronopsis pending taxonomic restudy of Burgess Shale specimens. Moysiuk and Caron (2019) recently described the appendages, digestive tract, and other soft tissues from exceptionally preserved specimens.

Description:

Morphology:

Adult dorsal exoskeletons reach about 20 mm in length. The semicircular cephalon has a narrow marginal rim around the front and sides and rounded genal angles. There are no dorsal eyes and no facial sutures. The narrow glabella comes to an ogival point, with no anterior median furrow; a transverse furrow crosses the glabella near its anterior. A pair of short genal spines are present. Two short thoracic segments carry lateral nodes on the axial rings. A narrowly rimmed pygidium, the same size and general shape as the cephalon, has abruptly angled anterolateral corners and a pair of short, backwards-directed marginal spines posterolaterally. The pygidial axis is broader than the glabella, but of similar outline, with a median tubercle between two transverse furrows. The pointed tip of the axis is separated by a gap from the pygidial rim posteriorly, without a median furrow. A saddle-shaped hypostome is present ventrally, unfused to the headshield. Unmineralized anatomy: The head probably bears six pairs of appendages, including one pair of elongate sensory antennules, two pairs of appendages with oar-like outer branches, and probably three pairs of stout walking limbs with a row of club-like projections. Additional walking limbs were present beneath the thorax (2) and pygidium (probably 4). The digestive tract curves dorsally from the mouth before emitting two pairs of branching gut glands, the first of which is the largest and occupies much of the space below the headshield. Behind this, the cylindrical midgut extends back to the pygidium. The hindgut begins roughly below the pygidial tubercle, and narrows considerably before reaching the anus below the tip of the pygidial axis.

Abundance:

Specimens likely assignable to this species are very common at Tokumm Creek and in the upper levels of the Marble Canyon quarry, where it is the most abundant artiopodan (Nanglu et al. 2020). Peronopsis columbiensis also occurs in notable numbers at Mount Odaray, Mount Stephen, and a few smaller localities (Rasetti 1951).

Maximum Size:
About 20 mm.

Ecology:

Life habits: Very abundant
Feeding strategies: Very abundant
Ecological Interpretations:

The mode of life of agnostids has been extensively debated (Fortey and Owens 1999). With the oar-like appendages capable of protruding while the animal was partially enrolled, agnostids certainly appear well-adapted for swimming (Müller and Walossek 1987). Together with their occurrence in mass mortality beds with wide geographic range, this evidence has been proposed to support a pelagic lifestyle (Fortey 1985). However, most specimens at the Burgess Shale are found in unrolled position, suggesting they did not live permanently enrolled. Further, Peronopsis is sometimes found in groups, associated with the remains of other Burgess Shale organisms, where it was potentially feeding on carrion or bacterial films, providing evidence for a benthic habitat. The huge, branching gut glands in the head likely acted as a food storage organ, possibly enabling a feast-and-famine lifestyle. The club-like outgrowths on the walking legs may have functioned in respiration (Moysiuk and Caron 2019).

References:

  • COTTON, T. J. and FORTEY, R. A. 2005. Comparative morphology and relationships of the Agnostida. In KOENEMANN, S. and JENNER, R. (eds.) Crustacea and Arthropod Relationships, CRC Press, 95–136 pp.
  • FORTEY, R. A. 1985. Pelagic trilobites as an example of deducing the life habits of extinct arthropods. Earth and Environmental Science Transactions of The Royal Society of Edinburgh, 76: 219–230.
  • FORTEY, R. A. and OWENS, R. M. 1999. Feeding habits in trilobites. Palaeontology, 42: 429–465.
  • HAUG, J. T., MAAS, A. and WALOSZEK, D. 2009. †Henningsmoenicaris scutula, †Sandtorpia vestrogothiensis gen. et sp. nov. and heterochronic events in early crustacean evolution. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 100: 311–350.
  • MOYSIUK, J. and CARON, J.-B. 2019. Burgess Shale fossils shed light on the agnostid problem. Proceedings of the Royal Society B: Biological Sciences, 286: 20182314.
  • MÜLLER, K. J. and WALOSSEK, D. 1987. Morphology, ontogeny, and life habit of Agnostus pisiformis from the Upper Cambrian of Sweden. Fossils and Strata, 19: 1–124.
  • NAIMARK, E. B. 2012. Hundred species of the genus Peronopsis Hawle et Corda, 1847. Paleontological Journal, 46: 945–1057.
  • NANGLU, K., CARON, J.-B. and GAINES, R. R. 2020. The Burgess Shale paleocommunity with new insights from Marble Canyon, British Columbia. Paleobiology, 46: 58–81.
  • RASETTI, F. 1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Miscellaneous Collections, 116: 1–277.
Other Links:

Kootenayscolex barbarensis

Kootenayscolex barbarensis, paratype, ROMIP 62972

Taxonomy:

Kingdom: Very abundant
Phylum: Very abundant
Higher Taxonomic assignment: Polychaetes
Species name: Kootenayscolex barbarensis
Remarks:

Kootenayscolex bears significant resemblance to modern polychaetes, but is currently considered outside of any extant group. It is currently considered as a stem-group polychaete, as are the other polychaetes from the Burgess Shale (Parry et al. 2016; Nanglu and Caron 2018).

Described by: Nanglu and Caron 2018
Description date: 2018
Etymology:

Kootenay — for Kootenay National Park in British Columbia, Canada, where the Marble Canyon fossil locality is located, and scolex from the Greek word for “worm,” which is a common suffix for polychaetes and reflects their general worm-shaped morphology.

barbarensis — from Barbara Polk Milstein, who is a volunteer at the Royal Ontario Museum and a long-time supporter of Burgess Shale research.

Type Specimens: Holotype ROMIP 64388; paratypes ROMIP 63099.1, and ROMIP 64389-, 64398
Other species:

Burgess Shale and vicinity: none
Other deposits: none

Age & Localities:

Age:
Middle Cambrian, Wuliuan Stage, upper part of the Burgess Shale Formation (around 507 million years old)
Principal localities:

Marble Canyon and the Walcott Quarry on Fossil Ridge, British Columbia.

History of Research:

Brief history of research:

This abundant polychaete, was first reported by Caron et al. in 2014 as a species comparable to Burgessochaeta setigera from the Walcott Quarry. Kootenayscolex was formally described as its own genus by Nanglu and Caron in 2018, using hundreds of new specimens discovered from the Marble Canyon fossil site in Kootenay National Park.

Description:

Morphology:

Kootenayscolex ranged in size from 1mm-30mm. Its head bore two long sensory structures known as palps, as well as a short medial antenna located between them. As with other polychaetes, its body was divided into a series of segments with the widest segments being in the middle of the body. Up to 25 segments have been observed in this species, each of which possessed a pair of parapodia which are fleshy, lateral outgrowths. From these parapodia extended bristles, known as chaetae, arranged into bundles. The dorsal bundles included up to 12 bristles, while the ventral bundles included up to 16 bristles which were arranged as a wider fan. The last segment of this animal, called the pygidium, was relatively simple and possessed no appendages. The head section, called the prostomium, also possessed a single set of parapodia and chaetae, directly adjacent to the mouth.

Abundance:

Kootenayscolex is the fifth most abundant species at Marble Canyon with 833 specimens (Nanglu et al. 2020).

Maximum Size:
About 3 cm.

Ecology:

Life habits: Very abundant
Feeding strategies: Very abundant
Ecological Interpretations:

Kootenayscolex has been reconstructed as a deposit feeding organism due to some specimens preserving sediment which filled the gut. This is particularly noticeable in specimens which have an enlarge anterior part of the gut which is nearly the width of the body. The elongate dorsal bristles were likely used for defense against predators, while the ventral bristles would have allowed for movement along the seafloor.

References:

  • NANGLU, K., AND J.-B., CARON. 2018. A new Burgess Shale polychaete and the origin of the annelid head revisited. Current Biology, 28 (2): 319-326.
  • NANGLU, K., CARON, J.-B. and GAINES, R. R. 2020. The Burgess Shale paleocommunity with new insights from Marble Canyon, British Columbia. Paleobiology, 46, 58-81.
  • PARRY, L. A., EDGECOMBE, G. D., EIBYE-JACOBSEN, D., AND J. VINTHER. 2016. The impact of fossil data on annelid phylogeny inferred from discrete morphological characters. Proceedings of the Royal Society B: Biological Sciences283 (1837): 20161378.
Other Links:

Fibulacaris nereidis

Fibulacaris nereidis, carapace ROMIP 64511

Taxonomy:

Kingdom: Very abundant
Phylum: Very abundant
Higher Taxonomic assignment: Hymenocarines, Family: Odaraiidae
Species name: Fibulacaris nereidis
Remarks:

Hymenocarines were early arthropods with bivalved carapaces and mandibles, forming the bulk of the first mandibulates (represented today by myriapods, crustaceans and insects) (Aria and Caron 2017; Vannier et al. 2018). In many hymenocarines, including Fibulacaris, determining the exact number and types of appendages on their head remains difficult, which hinders a detailed understanding of the evolutionary history of this group. Fibulacaris most probably belongs to the family Odaraiidae, a group of hymenocarines with highly multisegmented bodies, reduced or absent antennae and highly multisegmented legs.

Described by: Izquierdo-López & Caron
Description date: 2019
Etymology:

Fibulacaris – from a “fibula”, a type of brooch, the latin caris, meaning “crab” or “shrimp”

nereidis – from the Greek mythological creatures known as Nereids, the daughters of Nereus, given the similarities of Fibulacaris to the Burgess Shale odaraiid Nereocaris (Legg et al. 2012).

Type Specimens: Holotype ROMIP65380
Other species:

Burgess Shale and vicinity: None
Other deposits: None

Age & Localities:

Age:
Middle Cambrian (Wuliuan Stage), upper part of the Burgess Shale Formation (around 507 million years old)
Principal localities:

Marble Canyon, Tokumm Creek.

History of Research:

Brief history of research:

Several specimens of Fibulacaris nereidis were discovered at the Marble Canyon site in 2014 and nicknamed “epsilon-arthropod” based on the characteristic shape of its carapace. The majority of specimens were discovered at Mount Whymper and Tokumm Creek sites during the expeditions of 2016 and 2018, sometimes referred as “safety-pin”. Its genus and species were later described in 2019 (Izquierdo-López and Caron 2019).

Description:

Morphology:

Fibulacaris is generally small, with most specimens measuring around 1 cm. It has a distinct bivalved carapace enclosing its body laterally, covering up to two-thirds of its entire length. The dorsal side of the carapace is dome-shaped with a small crest that runs across the entire length, and a small spinose process on its posterior side. The frontal side of the carapace bends ventrally into a highly elongated spine, almost as long as the carapace itself. The ventral margins of the carapace are thicker, and end with a small process posteriorly on both sides. One pair of pedunculate eyes protrudes from the notches formed between the carapace and the spine. Other details about its head remain unknown, but antennae are either absent or highly reduced. The anterior side of the body is bent posteriorly, so that the eyes are facing backward. The body is multisegmented, subdivided into 30 segments, with each segment bearing limbs subdivided into two branches (biramous). Its tail has two small appendages shaped like a paddle (caudal rami).

Abundance:

Fibulacaris is rare at the Marble Canyon site, but very abundant (with more than 100 specimens) along Tokumm Creek.

Maximum Size:
About 2 cm.

Ecology:

Life habits: Very abundant
Feeding strategies: Very abundant
Ecological Interpretations:

Fibulacaris was likely a nektobenthic suspension feeder (Izquierdo-López and Caron 2019). Its gut is sometimes preserved as a three-dimensional structure, a type of preservation that has been associated with deposit feeders (Legg and Caron 2014). However, Fibulacaris’ carapace extends through its ventral side, indicating that this arthropod was not able to walk on surfaces and obtain organic material from the sediment, like a deposit feeder. Extant branchiopod crustaceans, such as many water fleas (Cladocera), have carapaces similar to that of Fibulacaris. Using their limbs, they generate small water currents carrying organic particles that pass through their limbs and carapace. Fibulacaris, could have used a similar suspension-feeding strategy. Given that the dorsal side of Fibulacaris was covered by its carapace, and that its eyes were facing towards the back of its body, it has been suggested that it was swimming upside down (Izquierdo-López and Caron 2019), as fairy shrimps do (Anostraca) (Fryer 2006). This way, Fibulacaris would have had capture organic particles falling from the water column, while being protected from predators from its back thanks to the carapace, from its ventral and posterior side thanks to the spine.

References:

  • ARIA, C. and CARON, J. B. 2017. Burgess Shale fossils illustrate the origin of the mandibulate body plan. Nature, 545: 89–92.
  • FRYER, G. 1968. Evolution and adaptive radiation in the Chydoridae (Crustacea: Cladocera): a study in comparative functional morphology and ecology. Philosophical Transactions of the Royal Society of London. B, Biological Sciences, 254: 221–382.
  • FRYER, G. 2006. The brine shrimp’s tale: a topsy turvy evolutionary fable. Biological Journal of the Linnean Society, 88(3): 377–382.
  • IZQUIERDO-LÓPEZ, A. and CARON, J. B. 2019. A possible case of inverted lifestyle in a new bivalved arthropod from the Burgess Shale. Royal Society Open Science, 6: 191350.
  • IZQUIERDO-LÓPEZ, A. and CARON, J. B. 2021. A Burgess Shale mandibulate arthropod with a pygidium: a case of convergent evolution. Papers in Palaeontology, 7: 1877–1894.
  • LEGG, D. A. and CARON, J. B. 2014. New Middle Cambrian bivalved arthropods from the Burgess Shale (British Columbia, Canada). Palaeontology, 57: 691–711.
  • LEGG, D. A., SUTTON, M. D., EDGECOMBE, G. D. and CARON, J. B. 2012. Cambrian bivalved arthropod reveals origin of arthrodization. Proceedings of the Royal Society B: Biological Sciences, 279: 4699–4704.
  • PARI, G., BRIGGS, D. E. G. and GAINES, R. R. 2022. The soft-bodied biota of the Cambrian Series 2 Parker Quarry Lagerstätte of northwestern Vermont, USA. Journal of Paleontology, 1–21.
  • VANNIER, J., ARIA, C., TAYLOR, R. S. and CARON, J. B. 2018. Waptia fieldensis Walcott, a mandibulate arthropod from the middle Cambrian Burgess Shale. Royal Society Open Science, 5:172206.
Other Links:

Yuknessia simplex

3D animation of Yuknessia simplex.
© Phlesch Bubble

Taxonomy:

Kingdom: Very abundant
Phylum: Very abundant
Higher Taxonomic assignment: Non applicable
Species name: Yuknessia simplex
Remarks:

Walcott (1919) considered Yuknessia as a green alga, a view shared by Conway Morris and Robison (1988). However, no revision of the type material from the Burgess Shale has been published since its original description and its affinities remain uncertain.

Described by: Walcott
Description date: 1919
Etymology:

Yuknessia – from Yukness Mountain (2,847m), a Peak in Yoho National Park, east of the Burgess Shale.

simplex – from the Latin simplex, meaning “simple,” in reference to the simple morphology of this alga.

Type Specimens: Holotype –USNM35406 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none

Other deposits: Yuknessia sp. from the Lower Cambrian Niutitan Formation in China (Yang et al., 2003).

Age & Localities:

Age:
Middle Cambrian, Bathyuriscus-Elrathina Zone to Ptychagnostus punctuosus Zone (approximately 505 million years ago).
Principal localities:

Burgess Shale and vicinity: The Walcott Quarry on Fossil Ridge and the Trilobite Beds on Mount Stephen.

Other deposits: Y. simplex is known from the Middle Cambrian Spence Shale and the Marjum and Wheeler Formations in Utah (Conway Morris and Robison, 1988).

History of Research:

Brief history of research:

This genus was described by Charles Walcott (1919) as a possible green alga. However, like all the algae from the Burgess Shale, it awaits a modern redescription (see Dalyia). Conway Morris and Robison (1988) described specimens of this species from several Utah deposits.

Description:

Morphology:

This alga has long branches emerging from a short but wide hollow stem covered of small conical elements or plates. The plates were the attachment sites of the branches. The branches show strong similarities with Dalyia and suggest the two species might be synonymous, with Yuknessia representing the main stem structure of the Dalyia branches.

Abundance:

Yuknessia is very rare and represents only 0.04% of the Walcott Quarry community (Caron and Jackson, 2008).

Maximum Size:
30 mm

Ecology:

Life habits: Very abundant
Feeding strategies: Very abundant
Ecological Interpretations:

The wide stem suggests this species was attached to the sea floor within the photic zone rather than being free floating.

References:

CARON, J.-B. AND D. A. JACKSON. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222-256.

CONWAY MORRIS, S. AND R. A. ROBISON. 1988. More soft-bodied animals from the Middle Cambrian of Utah and British Columbia. University of Kansas Paleontological Contributions, 122 p.

WALCOTT, C. 1919. Cambrian Geology and Paleontology IV. Middle Cambrian Algae. Smithsonian Miscellaneous Collections, 67(5): 217-260.

YANG, R., W. ZHANG, L. JIANG AND H. GAO. 2003. Chengjiang biota from the Lower Cambrian Niutitang Formation, Zunyi County, Guizhou Province, China. Acta Palaeontologica Sinica, 77: 145-150.

Other Links:

None

Testing this Change

Ptychagnostus praecurrens

Ptychagnostus praecurrens (USNM 116212). Complete individual originally interpreted as the holotype of Triplagnostus burgessensis by Rasetti (1951). Specimen length = 8 mm. Specimen dry – direct light. Walcott Quarry.

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

Taxonomy:

Kingdom: Very abundant
Phylum: Very abundant
Higher Taxonomic assignment: Trilobita (Order: Agnostida)
Species name: Ptychagnostus praecurrens
Remarks:

Trilobites are extinct euarthropods, probably stem lineage representatives of the Mandibulata, which includes crustaceans, myriapods, and hexapods (Scholtz and Edgecombe, 2006).

Described by: Westergård
Description date: 1936
Etymology:

Ptychagnostus – from the Greek ptycho, “pleated” (some species have pleat-like furrows on the cephalon), and agnostos, for “unknown” or “unknowable.”

praecurrens – from the Latin prae, “before,” and currens, “to run,” in reference to the old age of this fossil

Type Specimens: Holotype – SGU611; in the Geological Survey of Sweden (Sveriges geologiska undersökning – SGU), Uppsala, Sweden (Westergård, 1936)
Other species:

Burgess Shale and vicinity: none.

Other deposits: other species occur throughout the world in Middle Cambrian rocks.

Age & Localities:

Age:
Middle Cambrian, Bathyuriscus-Elrathina Zone (approximately 505 million years ago).
Principal localities:

The Walcott Quarry on Fossil Ridge.

History of Research:

Brief history of research:

Trilobites currently assigned to this genus and species have been described under several name combinations. Originally, Rasetti (1951) described it as Triplagnostus burgessensis, but subsequently (Rasetti, 1967) considered T. burgessensis to be a synonym of Ptychagnostus praecurrens (Westergård, 1936), a name retained by Peng and Robison (2000), despite numerous interim variations.

Description:

Morphology:

Hard parts: adult dorsal exoskeletons reach about 8 mm in length. The semicircular cephalon has a narrow marginal rim around the front and sides and sharply rounded the genal angles. There are no dorsal eyes and no facial sutures. The narrow glabella comes to an ogival point, with a median furrow extending across the short preglabellar field to the anterior margin; a transverse furrow crosses the glabella just in front of a low tubercle located behind the midpoint. Two short thoracic segments carry lateral nodes on the axial rings. A narrowly rimmed pygidium, the same size and general shape as the cephalon, has abruptly angled anterolateral corners. The pygidial axis is broader than the glabella, but of similar outline, with a median tubercle between two transverse furrows. The pointed tip of the axis reaches almost to the rim posteriorly, without a median furrow.

Unmineralized anatomy: not known

Abundance:

Very common in the Walcott Quarry on Fossil Ridge, where it is the most abundant trilobite (Caron and Jackson, 2008).

Maximum Size:
10 mm

Ecology:

Life habits: Very abundant
Feeding strategies: Very abundant
Ecological Interpretations:

Adult agnostine trilobites have often been regarded as pelagic organisms that swam or drifted in the water column. Evidence now suggests that most were members of the mobile benthic epifauna, possibly micrograzers or particle feeders, preferentially occupying colder, deeper, offshore waters.

References:

CARON, J.-B. AND JACKSON, D. A. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258:222-256.

PENG, S. C. AND ROBISON, R. A. 2000. Agnostoid biostratigraphy across the middle-upper Cambrian boundary in Hunan, China. Paleontological Society Memoir, no. 53 (supplement to Journal of Paleontology), 74(4), 104 pp.

RASETTI, F. 1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Miscellaneous Collections, 116(5): 277 pp.

RASETTI, F. 1967. Lower and Middle Cambrian trilobite faunas from the Taconic Sequence of New York. Smithsonian Miscellaneous Collections, 152(4): 112 pp.

SCHOLTZ, G. AND G. D. EDGECOMBE. 2006. The evolution of arthropod heads: reconciling morphological, developmental and palaeontological evidence. Development Genes and Evolution, 216:395-415.

WESTERGÅRD, A. H. 1936. Paradoxides oelandicus beds of Oland: with the account of a diamond boring through the Cambrian at Mossberga. Sveriges Geologiska Undersökning. Series C, no. 394, Årsbok 30, no. 1: 1-66.

Other Links:

Hazelia palmata

3D animation of Hazelia conferta and other sponges (Choia ridleyi, Diagoniella cyathiformis, Eiffelia globosa, Pirania muricata, Vauxia bellula, and Wapkia elongata) and Chancelloria eros a sponge-like form covered of star-shaped spines.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: Very abundant
Phylum: Very abundant
Higher Taxonomic assignment: Demospongea (Order: Monaxonida)
Species name: Hazelia palmata
Remarks:

Hazelia is considered a primitive demosponge, close to Falospongia and Crumillospongia (Rigby, 1986). Demosponges, the same group that are harvested as bath sponges, represent the largest class of sponges today.

Described by: Walcott
Description date: 1920
Etymology:

Hazelia – from Hazel Peak (3,151 m), the older name for Mount Aberdeen, located 4 km SSW of Lake Louise in Banff National Park, Alberta. Mount Aberdeen was named in honor of Lord Gordon in 1897, the Marquis of Aberdeen and the Governor General of Canada from 1893 to 1898.

palmata – from the Latin palm, “palm of the hand,” referring to the broad cup-shape of this sponge and its resemblance to a cupped hand.

Type Specimens: Lectotypes – USNM 66463 (H. palmata – type species), 66465 (H. delicatula), USNM 66505 (H. dignata), USNM 66473 (H. grandis), USNM 66474 (H. nodulifera), USNM 66472 (H. obscura); Holotypes – USNM 66476 (H. conferta), USNM 66779 (H. crateria), USNM 66475 (H. luteria) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA. Holotype –ROM53573 (H. lobata) in the Royal Ontario Museum, Toronto, Canada.
Other species:

Burgess Shale and vicinity: H. conferta Walcott, 1920, H. crateria Rigby, 1986, H. delicatula Walcott, 1920, H. dignata Walcott, 1920, H. grandis Walcott, 1920, H. lobata Rigby and Collins, 2004, H. luteria Rigby, 1986, H. nodulifera Walcott, 1920, H. obscura Walcott, 1920. Most species known from the Walcott Quarry (See Rigby, 1986 and Rigby and Collins, 2004).

Other deposits: H. walcotti (Resser and Howell, 1938) from the Early Cambrian Kinzers Formation of Pennsylvania (See Rigby, 1987).

Age & Localities:

Age:
Middle Cambrian, Bathyuriscus-Elrathina Zone to Bolaspidella Zone (approximately 505 million years ago).
Principal localities:

Burgess Shale and vicinity: Hazelia is particularly common in the Walcott Quarry and is less common in the Raymond and Collins Quarries on Fossil Ridge. Many species also occur on Mount Stephen at the Trilobite Beds, Tulip Beds (S7), and other smaller localities.

Other deposits: H. palmata Walcott, 1920 from the Middle Cambrian Marjum Formation (Rigby et al., 1997).

History of Research:

Brief history of research:

Walcott described seven species of Hazelia in his 1920 paper on the Burgess Shale sponges. The genus was redescribed by Rigby in 1986 when two new species were added and one excluded from the genus (H. mammillata now referred to Moleculospina mammillata). Rigby and Collins (2004) added another species based on new material collected by the Royal Ontario Museum.

Description:

Morphology:

Species of Hazelia have a large variation in morphology with wide cup-shaped forms (H. palmata, H. crateria, H. luteria), long cone-shaped forms (H. conferta, H. grandis, H. obscura), branched forms (H. delicatula, H. dignata), and nodular to lobate forms (H. lobata, H. nodulifera). While there is this significant variety of overall shapes, the different species of Hazelia have a common microstructure. The walls are thin and composed of small tightly packed simple spicules that form a net-like structure and diverge outwards producing a plumose pattern. The walls are perforated with small canals to allow water flow. The base of each sponge would have had a small attachment structure.

In addition to its open shield-like shape, H. palmata possesses distinct radial tracts of spicules which go beyond the margins of the sponge for at least a couple of millimeters.

Abundance:

Hazelia is very common in the Walcott Quarry and represents 9.5% of the community (Caron and Jackson, 2008).

Maximum Size:
150 mm

Ecology:

Life habits: Very abundant
Feeding strategies: Very abundant
Ecological Interpretations:

Hazelia would have lived attached to the sea floor. Particles of organic matter were extracted from the water as they passed through canals in the sponge’s wall.

References:

CARON, J.-B. AND D. A. JACKSON. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222-256.

RIGBY, J. K. 1986. Sponges of the Burgess Shale (Middle Cambrian), British Columbia. Palaeontographica Canadiana, 2: 105 p.

RIGBY, J. K. 1987. Early Cambrian sponges from Vermont and Pennsylvania, the only ones described from North America. Journal of Paleontology, 61: 451-461.

RIGBY, J. K. L. F. GUNTHER AND F. GUNTHER. 1997. The first occurrence of the Burgess Shale Demosponge Hazelia palmata Walcott, 1920, in the Cambrian of Utah. Journal of Paleontology, 71: 994-997.

RIGBY, J. K. AND D. COLLINS. 2004. Sponges of the Middle Cambrian Burgess Shale and Stephen Formations, British Columbia. Royal Ontario Museum Contributions in Science (1): 155 p.

WALCOTT, C. D. 1920. Middle Cambrian Spongiae. Cambrian Geology and Paleontology IV. Smithsonian Miscellaneous Collections, 67(6): 261-365.

Other Links:

None

Pollingeria grandis

Pollingeria grandis (GSC 8362). Slab with several specimens. Specimen length (largest) = 15 mm. Specimen dry – polarized light. Walcott Quarry.

© GEOLOGICAL SURVEY OF CANADA. PHOTO: JEAN-BERNARD CARON

Taxonomy:

Kingdom: Very abundant
Phylum: Very abundant
Higher Taxonomic assignment: Non applicable
Species name: Pollingeria grandis
Remarks:

Pollingeria is one of the least understood Burgess Shale organisms, and its systematic status is unknown (Briggs and Conway Morris, 1986).

Described by: Walcott
Description date: 1911
Etymology:

Pollingeria – from Mount Pollinger (2,816 m), northwest of the Burgess Shale. The name was given after Joseph Pollinger (1873-1943).

grandis – from the Latin grandis, “big, large,” in reference to the purported large size of the fossils.

Type Specimens: Syntypes –USNM57639-57641 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

Age:
Middle Cambrian, Bathyuriscus-Elrathina Zone (approximately 505 million years ago).
Principal localities:

The Walcott and Raymond Quarries on Fossil Ridge and smaller sites on Mount Field and Mount Stephen.

History of Research:

Brief history of research:

Pollingeria was first described by Walcott in a 1911 monograph dealing with various Burgess Shale worms. Walcott interpreted these fossils as the individual scales of a larger organism resembling Wiwaxia. However, this interpretation was doubted (Conway Morris, 1979), and firmly rejected after the restudy of Wiwaxia (Conway Morris, 1985). The affinities of Pollingeria have remained difficult to establish (Briggs and Conway Morris, 1986).

Description:

Morphology:

The shape of this fossil is ovoid but variable in details and most individuals range from 10 to 15 mm in length. A distinctive feature is a series of narrow tubular elements that are darker and often slightly raised; these are twisted and contorted and do not appear to be parts of a gut.

Abundance:

Pollingeria is locally very abundant with hundreds of specimens on some bedding surfaces. In the Walcott Quarry this species represents 5.83% of the specimens counted in the community (Caron and Jackson, 2008).

Maximum Size:
15 mm

Ecology:

Life habits: Very abundant
Feeding strategies: Very abundant
Ecological Interpretations:

Not enough is known about this organism to interpret its ecology.

References:

BRIGGS, D. E. G. AND S. CONWAY MORRIS. 1986. Problematica from the Middle Cambrian Burgess Shale of British Columbia, p. 167-183. In A. Hoffman and M. H. Nitecki (eds.), Problematic fossil taxa (Oxford Monographs on Geology and Geophysics No. 5). Oxford University Press & Clarendon Press, New York.

CARON, J.-B. AND D. A. JACKSON. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222-256.

CONWAY MORRIS, S. 1979. The Burgess Shale (Middle Cambrian) fauna. Annual Review of Ecology and Systematics, 10(1): 327-349.

CONWAY MORRIS, S. 1985. The Middle Cambrian metazoan Wiwaxia corrugata (Matthew) from the Burgess Shale and Ogygopsis Shale Shale, British Columbia, Canada. Philosophical Transactions of the Royal Society of London, Series B, 307:507-582.

WALCOTT, C. 1911. Cambrian Geology and Paleontology II. Middle Cambrian annelids. Smithsonian Miscellaneous Collections, 57(5): 109-145.

Other Links:

None