The Burgess Shale

Tokummia katalepsis

Tokummia katalepsis, paratype, ROMIP 63826

Taxonomy:

Kingdom: Common
Phylum: Common
Higher Taxonomic assignment: Hymenocarines, Family Protocarididae (Miller 1889).
Species name: Tokummia katalepsis
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 & Caron 2017; Vannier et al. 2018). Tokummia was a close relative of Branchiocaris, both grouped within the eponymous family Protocarididae Miller, 1889—one of the oldest formal taxa from the Burgess Shale. The relationship of Protocarididae within hymenocarines, as well as the relative placement of hymenocarines within early mandibulates is still under investigation (Aria 2022; Izquierdo-López & Caron 2022).

Described by: Aria and Caron
Description date: 2017
Etymology:

Tokummia — from Tokumm Creek, a river of the Kootenay area, in British Columbia, running through Marble Canyon, near the outcrop where the fossil was first found.

katalapsis — from the Greek, meaning “seizing, grasping,” by reference to the well-developed pincers of the animal.

Type Specimens: Holotype ROMIP 63823; paratypes ROMIP 63014, 63081, 63824–63827, 63736 (7 specimens), in 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:

The Marble Canyon and Tokumm Creek areas of the Burgess Shale, British Columbia.

History of Research:

Brief history of research:

Tokummia was discovered during the original excavation of the Marble Canyon locality in 2012, along Yawunik and other taxa characteristic of this area. Additional specimens were later discovered during quarrying operations and along Tokumm Creek. Tokummia’s description was published in 2017: Tokummia’s size and quality of preservation helped identify mandibles and other diagnostic traits of mandibulates. Mandibles were also identified in Branchiocaris in the same study. This study partially rehabilitated original interpretations by Derek Briggs recognizing mandibulate affinities of Cambrian bivalved arthropods (hymenocarines) (Briggs 1992) but were not without their issues, notably that of the presence of an intercalary segment (e.g. Edgecombe 2017). However, research on hymenocarines has since been supportive of the mandibulate affinity of these arthropods (Vannier et al. 2018; Izquierdo-López & Caron 2022). Tokummia therefore remains central to our modern understanding of early arthropod evolution as a whole (Aria 2022).

Description:

Morphology:

Like other protocaridids, Tokummia’s long, tubular, multisegmented body is largely enclosed in a broad bivalved carapace with ample, lobate corners. Small processes are present medially at the front and rear of both valves. Eyes are very reduced or absent. The very front of the animal bears a bilobed organ covered by triangular sclerite. A pair of short, stout, multisegmented antennules are the most anterior appendages. The next pair of appendages are large, round mandibles, followed by modified appendages identified as maxillules and maxillae. The first pair of thoracic limbs are very large pincers projecting at the front of the animal, and therefore called maxillipeds. Trunk limbs are composed of well-developed walking legs ending in strong claws, and of lobate flaps that get much larger starting with trunk limb pair 9. There is a total of about 50 limb pairs in the trunk, one for each segment, which gradually decrease in size towards the back. Some tergites are fused at the back of the animal, forming a plate, and the tailpiece is a pair of caudal rami, typical of mandibulates.

Abundance:

The original description was based on 21 specimens (Aria & Caron 2017), but this count has so far doubled (Nanglu et al. 2020). Tokummia is a signature taxon of both the Marble Canyon quarry and the Tokumm sites.

Maximum Size:
About 15 cm.

Ecology:

Life habits: Common
Feeding strategies: Common
Ecological Interpretations:

The combination of large pincers and strong walking appendages in Tokummia suggests it was a nektobenthic predator. However, as in Branchiocaris and Protocaris, the absence of distinct eyes in the fossils, implying they were either very reduced or absent, indicates that the predatory lifestyle of Tokummia and other Protocarididae had its own specificity. Protocaridids either relied more heavily on their other sensory organs or were perhaps more passive predators.

References:

  • ARIA, C. 2022. The origin and early evolution of arthropods. Biological Reviews, 97, 1786–1809.
  • ARIA, C. and CARON, J. B. 2017. Burgess Shale fossils illustrate the origin of the mandibulate body plan. Nature, 545, 89–92.
  • BRIGGS, D. E. G. 1992. Phylogenetic significance of the Burgess Shale crustacean Canadaspis. Acta Zoologica, 73, 293–300.
  • EDGECOMBE, G. D. 2017. Palaeontology: The cause of jaws and claws. Current Biology, 27, R796–R815.
  • IZQUIERDO-LÓPEZ, A. and CARON, J.-B. 2022. The problematic Cambrian arthropod Tuzoia and the origin of mandibulates revisited. Royal Society Open Science, 9.
  • MILLER, S. A. 1889. North American geology and palaeontology for the use of amateurs, students and scientists. Western Methodist Book Concern, Cincinnati.
  • 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.
  • 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.
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Nereocaris exilis

Nereocaris briggsi, holotype ROMIP 62153

Taxonomy:

Kingdom: Common
Phylum: Common
Higher Taxonomic assignment: Hymenocarines, Family: Odaraiidae
Species name: Nereocaris exilis
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 Nereocaris, determining the exact number and types of appendages in their head remains difficult, which hinders a detailed understanding of the evolutionary relationships inside this group. Nereocaris 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: Legg, D. A., Sutton, M. D., Edgecombe, G. D., Caron, J-B.
Description date: 2012
Etymology:

Nereocaris – After “Nereus”, the Greek titan with a fish-like tail and the Latin caris, meaning “crab” or “shrimp”, and

exilis – from the Latin exilis, meaning “slender”.

Type Specimens: dsfsdfdsfdsfdasf
Other species:

Holotype ROMIP61831

Age & Localities:

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

Tulip Beds (S7) (N. exilis) and the Collins Quarry (N. briggsi).

History of Research:

Brief history of research:

The first description of Nereocaris exilis was published in 2012 based on specimens from the Tulip Beds site in Mount Stephen (Yoho National Park). Two years later, Nereocaris briggsi was described based on specimens from the Collins Quarry in Mount Stephen (Legg and Caron 2014). Nereocaris was originally described with a median eye protruding from a single eye peduncle located between the lateral eyes (Legg et al. 2012; Legg and Caron 2014). This structure was later reinterpreted as one of a pair of frontal filaments; short unsegmented limb-like structures with a sensorial function (Izquierdo-López and Caron 2022). Similarly, the tail fan of Nereocaris exilis was initially interpreted as having six pairs of lateral caudal rami (termed telson processes in the original study) and one medial telson process. This structure was later reinterpreted as two pairs of three-partite caudal rami borne by the terminal segment (“te” in Izquierdo-López and Caron, 2022), and was also reconstructed as such for N. briggsi (Izquierdo-López and Caron 2022). The discovery of Nereocaris and the phylogenetic analyses adjunct to the publication have been key to the interpretation of hymenocarines as earliest euarthropods (Legg et al. 2013; Fu et al. 2022) (or ‘upper stem-euarthropods’ based on Ortega-Hernández 2014). The discovery of mandibles in several hymenocarines (Aria and Caron 2017; Vannier et al. 2018; Zhai et al. 2019) has prompted the reinterpretation of this group as mandibulates, although the mandibulates affinities of Nereocaris and other odaraiids remain unclear pending clearer resolution of their head appendages.

Description:

Morphology:

The carapace of Nereocaris has a dome-like shape, compressed laterally, which becomes progressively wider towards the back of the animal. The top of the carapace bears a dorsal crest (keel) that runs across its entire length and extends posteriorly into a small process. The carapace is truncated anteriorly, and each valve extends towards the ventral side, terminating into an anterior hook. The carapace valves extend beyond the length of the legs, and in N. briggsi extend across the ventral side, similar to Odaraia alata. The head bears one pair of short pedunculate eyes and one pair of thin and small, unsegmented appendages (frontal filaments). Antennulae appear to be absent, and further cephalic specializations are unknown from the material available. The body of Nereocaris is highly multisegmented, reaching more than 90 segments in N. exilis. The trunk is subdivided into a thoracic region with limbs and a long limbless abdomen. Limbs are short, subdivided into two branches (biramous): a walking leg (endopod) and a seemingly paddle-like flap (exopod). Based on N. briggsi, the walking legs are probably subdivided into 14 or similar segments (podomeres). The exact morphology and size of the exopods is not well-preserved, but darker areas close to the legs’ base could indicate their approximate shape and length. The terminal segment is distinctly larger than the preceding segments and extends into a blunt process towards the posterior side of the animal (the “mtp” in Legg & Caron, 2014). This last segment bears one pair of caudal rami, each being partly subdivided into three smaller segments (tripartite). Each segment bears one spine on its outer edge.

Abundance:

Nereocaris exilis is rare, only known from three specimens from the same locality. Nereocaris briggsi is highly abundant in its locality, with over 190 specimens known.

Maximum Size:
About 14.2 cm (N. exilis)

Ecology:

Life habits: Common
Feeding strategies: Common
Ecological Interpretations:

The limbs of Nereocaris exilis do not extend beyond the carapace ventral margin, indicating that they were not used for crawling. By contrast, the limbs of Nereocaris briggsi protrude from the carapace, but these were considered ill-suited to walk on the benthos (Legg and Caron 2014). For this reason, Nereocaris was reconstructed as a nektonic species, using its long abdomen as a means of propulsion (Legg et al. 2012; Perrier et al. 2015). N. exilis could have been a suspension-feeder, based on the lack of any raptorial or similar predatory limbs, but this possibility was questioned based on the lack of endites or setae on the limbs (Legg et al. 2012), which are widely used by extant filter-feeding crustaceans (Riisgård and Larsen 2010). A straight gut in N. briggsi, a simple tube filled with sediment may support the presence of a suspension or deposit feeding lifestyle, in which the animal would have consumed mud containing organic material (Legg and Caron 2014). It was also hypothesized that multiple odaraiids (Izquierdo-López and Caron 2022), most prominently Fibulacaris (Izquierdo-López and Caron 2019), could have swum upside-down, thus facilitating the capture of particles by the carapace. Whether Nereocaris could have adopted such behaviour remains uncertain.

References:

  • ARIA, C. and CARON, J. B. 2017. Burgess Shale fossils illustrate the origin of the mandibulate body plan. Nature, 545: 89–92.
  • FU, D., LEGG, D. A., DALEY, A. C., BUDD, G. E., WU, Y. and ZHANG, X. 2022. The evolution of biramous appendages revealed by a carapace-bearing Cambrian arthropod. Philosophical Transactions of the Royal Society of London B, 377.
  • 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. 2022. Extreme multisegmentation in a giant bivalved arthropod from the Cambrian Burgess Shale. IScience, 25, 104675.
  • LEGG, D., SUTTON, M. D. and EDGECOMBE, G. D. 2013. Arthropod fossil data increase congruence of morphological and molecular phylogenies. Nature Communications, 4: 1–7.
  • 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.
  • ORTEGA-HERNÁNDEZ, J. 2014. Making sense of ‘lower’ and ‘upper’ stem-group Euarthropoda, with comments on the strict use of the name Arthropoda von Siebold, 1848. Biological Reviews, 91: 255–273.
  • PERRIER, V., WILLIAMS, M. and SIVETER, D. J. 2015. The fossil record and palaeoenvironmental significance of marine arthropod zooplankton. Earth-Science Reviews, 146: 146–162.
  • RIISGÅRD, H. U. and LARSEN, P. S. 2010. Particle capture mechanisms in suspension-feeding invertebrates. Marine Ecology Progress Series, 418: 255–293.
  • 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.
  • ZHAI, D., ORTEGA-HERNÁNDEZ, J., WOLFE, J. M., HOU, X.-G., CAO, C. and LIU, Y. 2019. Three-dimensionally preserved appendages in an early Cambrian stem-group pancrustacean. Current Biology, 29: 171–177.
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Loricicaris spinocaudatus

Loricicaris spinocaudatus, paratype, ROMIP 43188

Taxonomy:

Kingdom: Common
Phylum: Common
Higher Taxonomic assignment: Hymenocarines, Family Protocarididae (Miller 1889).
Species name: Loricicaris spinocaudatus
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 & Caron 2017; Vannier et al. 2018). Loricicaris was a close relative of Branchiocaris, both grouped within the eponymous family Protocarididae Miller, 1889—one of the oldest formal taxa from the Burgess Shale. The relationship of Protocarididae within hymenocarines, as well as the relative placement of hymenocarines within early mandibulates is still under investigation (Aria 2022; Izquierdo-López & Caron 2022).

Described by: Legg and Caron
Description date: 2014
Etymology:

Loricicaris — from the Latin “lorica,” meaning armoured or armour plating, referring to the armoured (spinose) appearance of the trunk, and “caris” meaning shrimp.

spinocaudatus — from the Latin “spinosus” and “cauda,” meaning spiny and tail respectively, in reference to the spinose trunk and tailpiece of this species.

Type Specimens: Holotype ROMIP 62143 and paratype ROMIP 43188, in 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:

The Collins Quarry on Mount Stephen.

History of Research:

Brief history of research:

Following the discovery and initial excavation of the Collins Quarry on Mount Stephen (initially referred as “locality 9”, (Collins et al. 1983)), the small protocaridid material from the Collins Quarry had been referred to as possible juvenile specimens of Branchiocaris (Briggs & Robison 1984). The material was formally described much later as a new genus and species by Legg and Caron (2014), alongside Nereocaris briggsi, and interpreted in the light of a very basal placement of bivalved arthropods in the evolution of the group—a view that has since given way to the mandibulate classification of these taxa (Aria 2022).

Description:

Morphology:

Loricicaris has a stout, tubular, multisegmented body largely enclosed in a broad bivalved carapace with ample, lobate corners, like other protocaridids. Eyes are very reduced or absent. The very front of the animal bears a rounded sclerite. A pair of short, stout, multisegmented antennules are the most anterior appendages. The rest of the head is poorly known, but clawed appendages are present in proximity to the antennules. The trunk limbs bear round exopods; endopods are reduced or absent. The tailpiece is a pair of caudal rami bearing setae.

Abundance:

24 specimens (Legg & Caron 2014).

Maximum Size:
About 3 cm.

Ecology:

Life habits: Common
Feeding strategies: Common
Ecological Interpretations:

Loricicaris was considered by its authors to be a nektobenthic deposit feeder, based on the possession of a swimmer body and three-dimensional preservation of the gut (Legg & Caron 2014). Loricicaris could be a predator or particle feeder like other hymenocarines.

References:

  • ARIA, C. 2022. The origin and early evolution of arthropods. Biological Reviews, 97, 1786–1809.
  • ARIA, C. and CARON, J. B. 2017. Burgess Shale fossils illustrate the origin of the mandibulate body plan. Nature, 545, 89–92.
  • BRIGGS, D. E. G. and ROBISON, R. A. 1984. Exceptionally preserved nontrilobite arthropods and Anomalocaris from the Middle Cambrian of Utah. The University of Kansas Paleontological Contributions, 111, 1–23.
  • 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.
  • IZQUIERDO-LÓPEZ, A. and CARON, J.-B. 2022. The problematic Cambrian arthropod Tuzoia and the origin of mandibulates revisited. Royal Society Open Science, 9.
  • LEGG, D. and CARON, J. B. 2014. New Middle Cambrian bivalved arthropods from the Burgess Shale (British Columbia, Canada). Journal of Paleontology, 57, 691–711.
  • MILLER, S. A. 1889. North American geology and palaeontology for the use of amateurs, students and scientists. Western Methodist Book Concern, Cincinnati.
  • 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.
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Gyaltsenglossus senis

Gyaltsenglossus senis, holotype, ROMIP 65606.1

Taxonomy:

Kingdom: Common
Phylum: Common
Higher Taxonomic assignment: No subphylum assignment
Species name: Gyaltsenglossus senis
Remarks:

Gyaltsenglossus is currently considered a stem-group hemichordate. It has features of both the modern hemichordate groups in that it has the long proboscis and worm-shaped body of the Enteropneusta (acorn worms) and the crown of feeding tentacles of the Pterobranchia.

Described by: Nanglu et al. 2020
Description date: 2020
Etymology:

Gyaltsen (pronounced “GEN-zay”) in honour of the lead author’s father, and glossus from the Greek glossa, meaning tongue, a common generic suffix for hemichordates.

Senis from the Latin senex, meaning old.

Type Specimens: Holotype ROMIP 65606.1
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:

Odaray Mountain, Yoho National Park.

History of Research:

Brief history of research:

Gyaltsenglossus was described in 2020 based on 33 specimens, all collected from Odaray Mountain. Only the holotype preserves all major anatomical features.

Description:

Morphology:

: Gyaltsenglossus is a worm roughly 2 cm long. At the anterior end, it has an elongate, ovoid, muscular proboscis. Behind the proboscis is a set of six arms which bore roughly 15 pairs of tentacles. These arms were roughly 1.5 times as long as the proboscis, based on measurements taken from the holotype. The tentacles give the arms an overall fuzzy or foliose appearance. Behind the feeding arms is a roughly cylindrical trunk, which tapers from the largest point at the anterior and becomes smaller towards the posterior end of the animal. On the dorsal side of the trunk, directly behind the feeding arms, an elevated area leads to a set of thin, thread-like appendages. Posterior to the trunk is a bulbous structure with internal features preserved more darkly than in the surrounding tissues. This bulbous structure may constitute thickened tissue. In some specimens, a gut ending prior to the posterior bulbous structure is preserved.

Abundance:

33 specimens were described.

Maximum Size:
About 2 cm.

Ecology:

Life habits: Common
Feeding strategies: Common
Ecological Interpretations:

The morphology of Gyaltsenglossus suggests that it had a two-part feeding ecology. The long proboscis could have been used to feed directly from the marine mud on which the animal would have lived, in a manner similar to that of modern-day acorn worms. The feeding arms could also have been used to filter food particles from the water above the organism, as done by pterobranchs. The posterior bulbous appendage may have been used to anchor Gyaltsenglossus to the seafloor, particularly when it was feeding on small particles from the water.

References:

  • 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
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Capinatator praetermissus

Capinatator praetermissus, ROMIP 64247

Taxonomy:

Kingdom: Common
Phylum: Common
Higher Taxonomic assignment: None
Species name: Capinatator praetermissus
Remarks:

Capinatator is considered an early chaetognath unrelated to modern forms (Briggs and Caron (2017), see also Vinther and Parry (2019)). Modern chaetognaths have traditionally been difficult to classify based on morphological characters, but thanks to progress in phylogenomic techniques, they are currently viewed as members of the Gnathifera, a clade of very small organisms with complex jaws (Marlétaz et al. 2019).

Described by: Briggs and Caron
Description date: 2017
Etymology:

Capinatator — from the Latin “capere,” which means “to grasp,” and the Latin “natator,” which means “swimmer.”

praetermissus — from the Latin “praeter,” which means “besides, beyond”, and “mittere” which means “to send away, to reach out”, referring to the fact that this fossil has long been overlooked.

Type Specimens: Holotype ROMIP 64271_1, at the Royal Ontario Museum, Toronto, Canada
Other species:

Burgess Shale and vicinity: None

Other deposits: None

Age & Localities:

Age:
Middle Cambrian, Wuliuan stage, Burgess Shale Formation (around 505 million years old).
Principal localities:

Mount Stephen (Collins Quarry locality), Walcott Quarry, British Columbia.

History of Research:

Brief history of research:

Two separate species from the Burgess Shale have previously been regarded as chaetognaths, Amiskwia sagittiformis (Walcott 1911) and Oesia disjuncta (Szaniawski 2005). Since then, Amiskwia has been redescribed as a gnathiferan (Caron and Cheung 2019; Vinther and Parry 2019) and Oesia as a hemichordate (Nanglu et al. 2020). Conway Morris (2009) illustrated the first grasping spines of a Burgess Shale chaetognath from a specimen originally discovered by Walcott. Body fossils of Cambrian chaetognaths are extremely rare, with only a few specimens known from China likely representing just one species (Vannier et al. 2007). At the time Capinatator was published, another species was also described from China with a very similar arrangement of spines but with no evidence of the body except for traces of the head (Shu et al. 2017).

Description:

Morphology:

The body is divided into a large head, short neck, an elongate trunk, and a short tail. Lateral and terminal fins did not preserve; these are the first features to decay (Casenove et al. 2011). The head has about 50 simple grasping spines, 25 on each side of the mouth. The spines are claw-shaped and each one may have been reinforced at the tip by a conical structure. A gut trace are visible in some specimens.

Abundance:

49 specimens were initially described, but only 18 preserve evidence of the body.

Maximum Size:
About 9.5 cm.

Ecology:

Life habits: Common
Feeding strategies: Common
Ecological Interpretations:

Like modern species, Capinatator likely swam by undulating its body, using its caudal fin for propulsion and lateral fins for added maneuverability. The rarity of specimens preserved with the body suggests that this species did not normally live along the seafloor where it would have been subject to being entrapped by rapid mudflows. Instead, it is likely that Capinatator fed in the water column using its strong grasping spines to capture small swimming prey.

References:

  • BRIGGS, D. E. G. and CARON, J. B. 2017. A large Cambrian chaetognath with supernumerary grasping spines. Current Biology, 27, 2536-2543.e1.
  • CARON, J.-B. and CHEUNG, B. 2019. Amiskwia is a large Cambrian gnathiferan with complex gnathostomulid-like jaws. Communications Biology, 2, 164.
  • CASENOVE, D., OJI, T. and GOTO, T. 2011. Experimental Taphonomy of Benthic Chaetognaths: Implications for the Decay Process of Paleozoic Chaetognath Fossils. Paleontological Research, 15, 146-153, 8.
  • CONWAY MORRIS, S. 2009. The Burgess Shale animal Oesia is not a chaetognath: A reply to Szaniawski (2005). Acta Palaeontologica Polonica, 54, 175-179.
  • MARLÉTAZ, F., PEIJNENBURG, K. T. C. A., GOTO, T., SATOH, N. and ROKHSAR, D. S. 2019. A new spiralian phylogeny places the enigmatic arrow worms among gnathiferans. Current Biology, 29, 312-318.e3.
  • NANGLU, K., CARON, J.-B. and CAMERON, C. B. 2020. Cambrian tentaculate worms and the origin of the hemichordate body plan. Current Biology, 30, 4238-4244.e1.
  • SHU, D., CONWAY MORRIS, S., HAN, J., HOYAL CUTHILL, J. F., ZHANG, Z., CHENG, M. and HUANG, H. 2017. Multi-jawed chaetognaths from the Chengjiang Lagerstätte (Cambrian, Series 2, Stage 3) of Yunnan, China. Palaeontology, 60, 763-772.
  • SZANIAWSKI, H. 2005. Cambrian chaetognaths recognized in Burgess Shale fossils. Acta Palaeontologica Polonica, 50, 1-8.
  • VANNIER, J., STEINER, M., RENVOISÉ, E., HU, S. X. and CASANOVA, J. P. 2007. Early Cambrian origin of modern food webs: evidence from predator arrow worms. Proceedings of the Royal Society B: Biological Sciences, 274, 627-633.
  • VINTHER, J. and PARRY, L. A. 2019. Bilateral jaw elements in Amiskwia sagittiformis bridge the morphological gap between gnathiferans and chaetognaths. Current Biology, 29, 881-888.e1.
  • WALCOTT, C. 1911. Cambrian Geology and Paleontology II. Middle Cambrian annelids. Smithsonian Miscellaneous Collections, 57(5), 109-145.
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Zacanthoides romingeri

Zacanthoides romingeri (figure 3) illustrated by Rominger (1887) as Embolimus spinosa.

Taxonomy:

Kingdom: Common
Phylum: Common
Higher Taxonomic assignment: Trilobita (Order: Corynexochida)
Species name: Zacanthoides romingeri
Remarks:

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

Described by: Rominger
Description date: 1887
Etymology:

Zacanthoides – probably from the Greek z(a), “very,” and akanthion, “thistle” or “porcupine” or “hedgehog,” and oides, “resembling;” thus, very thistle- or porcupine-like.

romingeri – after Carl Rominger, a Michigan paleontologist who in 1887 published the first descriptions of trilobites from Mount Stephen.

Type Specimens: Type status under review – UMMP 4871 (2 specimens), University of Michigan Museum of Paleontology, Ann Arbor, Michigan, USA.
Other species:

Burgess Shale and vicinity: Zacanthoides sexdentatus, Z. submuticus, Z. longipygus, Z. planifrons, Z. divergens, all from older and younger Middle Cambrian rocks on Mount Stephen, Mount Odaray, and Park Mountain (Rasetti, 1951).

Other deposits: other species elsewhere in North America.

Age & Localities:

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

The Trilobite Beds on Mount Stephen.

History of Research:

Brief history of research:

In 1887 Carl Rominger published an engraving of a nearly complete and markedly spiny trilobite and named it Embolimus spinosa. In 1908 Charles Walcott introduced the combination Zacanthoides spinosus for the Mount Stephen species and for a similar trilobite from Nevada. The next change came in 1942, when Charles Resser at the United States National Museum asserted that the Mount Stephen species was sufficiently distinct that it required a new name. Resser chose to honour the man who first formally described many of the common Mount Stephen trilobites, and Zacanthoides romingeri remains the combination in use today.

Description:

Morphology:

Hard parts: adult dorsal exoskeletons can reach up to 6 cm in length, tapering back from a large crescentic cephalon through a thorax of nine segments, to a relatively small rounded-triangular pygidium with long marginal spines.

The wide free cheeks bear strong genal spines; short, thorn-like intragenal spines mark the posterior corners of the fixed cheeks. The glabella is long and narrow, slightly expanded forwards. There are four pairs of lateral glabellar furrows; the anterior two pairs are weaker and angled to the front, the stronger posterior two are angled back. Very long narrow eyes that bow strongly outward are located far back on the cephalon. The occipital ring extends rearward into a strong, broad-based spine. Long, blade-shaped terminal spines on the wide pleurae curve progressively more backwards. A slender needle-like spine arises from the axial ring of the eighth thoracic segment. There are four pygidial axial rings; five pairs of marginal spines, each successively shorter, are directed rearwards and extend beyond the tip of the pygidium.

Unmineralized anatomy: not known.

Abundance:

Zacanthoides romingeri is moderately abundant at the Mount Stephen Trilobite Beds but absent from Fossil Ridge. Complete trilobites with the free cheeks in place are very scarce, and this species is mostly found as disarticulated sclerites. Its distinctive characteristics, however, usually allow even isolated pieces to be readily identified.

Maximum Size:
60 mm

Ecology:

Life habits: Common
Feeding strategies: Common
Ecological Interpretations:

Zacanthoides romingeri adults very likely walked along the sea bed. The overall spinosity of this species may have served as a deterrent to predators, or possibly helped to break up the visual outline of the animal, making it harder to see on the sea floor (Rudkin, 1996).

References:

RASETTI, F. 1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky Mountains. Smithsonian Miscellaneous Collections, 116 (5): 1-277.

RESSER, C. E. 1942. Fifth contribution to nomenclature of Cambrian trilobites. Smithsonian Miscellaneous Collections, 101 (15): 1-58.

ROMINGER, C. 1887. Description of primordial fossils from Mount Stephens, N. W. Territory of Canada. Proceedings of the Academy of Natural Sciences of Philadelphia, 1887: 12-19.

RUDKIN, D. M. 1996. The Trilobite Beds of Mount Stephen, Yoho National Park, p. 59-68. In R. Ludvigsen (ed.), Life in Stone – A Natural History of British Columbia’s Fossils. UBC Press, Vancouver.

RUDKIN, D. M. 2009. The Mount Stephen Trilobite Beds, p. 90-102. In J.-B. Caron and D. Rudkin (eds.), A Burgess Shale Primer – History, Geology, and Research Highlights. The Burgess Shale Consortium, Toronto.

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.

WALCOTT, C. D. 1888. Cambrian fossils from Mount Stephens, Northwest Territory of Canada. American Journal of Science, Series 3, 36: 163-166.

WALCOTT, C. D. 1908. Mount Stephen rocks and fossils. Canadian Alpine Journal, 1:232-248.

Other Links:

Yohoia tenuis

3D animation of Yohoia tenuis.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Common
Phylum: Common
Higher Taxonomic assignment: Unranked clade Megacheira? (stem group arthropods)
Species name: Yohoia tenuis
Remarks:

Yohoia was originally considered to be a branchiopod crustacean (Walcott, 1912; Simonetta, 1970), but was also described as being closely related to the chelicerates (Briggs and Fortey, 1989; Wills et al., 1998; Cotton and Braddy, 2004). Other analyses suggest that Yohoia belongs in the group of “great appendage” arthropods, the Megacheira, together with LeanchoiliaAlalcomenaeus and Isoxys (Hou and Bergström, 1997; Budd, 2002). The megacheirans have been suggested to either be stem-lineage chelicerates (Chen et al. 2004; Edgecombe, 2010), or stem-lineage euarthropods (Budd, 2002).

Described by: Walcott
Description date: 1912
Etymology:

Yohoia – from the Yoho River, Lake, Pass, Glacier, Peak (2,760 m) and Park, British Columbia, Canada. “Yoho” is a Cree word expressing astonishment.

tenuis – from the Latin tenuis, “thin,” referring to its slender body.

Type Specimens: Lectoype –USNM57699 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, Raymond and Collins Quarries on Fossil Ridge.

History of Research:

Brief history of research:

Yohoia was first described by Walcott (1912), who designated the type species Y. tenuis based on six specimens, and a second species, Y. plena, based on one specimen. Additional specimens of Y. tenuis were described by Simonetta (1970), and a major redescription of Yohoia tenuis was then undertaken by Whittington (1974), based on over 400 specimens of this species. Whittington (1974) invalidated Y. plena, upgrading it to its own genus, Plenocaris plena, leaving Y. tenuis as the only species of YohoiaYohoia has since been included in several studies on arthropod phylogeny and evolution (e.g., Briggs and Fortey, 1989; Hou and Bergström, 1997; Wills et al., 1998; Budd, 2002; Chen et al., 2004; Cotton and Braddy, 2004).

Description:

Morphology:

The body of Yohoia consists of a head region encapsulated in a cephalic shield and 14 body segments, ending in a paddle-shaped telson. The dorsal head shield is roughly square and extends over the dorsal and lateral regions of the head. There is a pair of great appendages at the front of the head. Each appendage consists of two long, thin segments that bend like an elbow at their articulation, with four long spines at the tip. Three pairs of long, thin, segmented appendages project from beneath the head shield behind the great appendages.

The body behind the head consists of ten segments with tough plates, or tergites, that extend over the back and down the side of the animal, ending in backward-facing triangular points. The first of these body segments may have an appendage that is segmented and branches into two (biramous), with a segmented walking limb bearing a flap-like extension. The following nine body segments have only simple flap-shaped appendages fringed with short spines or setae. The next three body segments have no appendages, and the telson is a paddle-shaped plate with distal spines.

Abundance:

Over 700 specimens of Yohoia are known from the Walcott Quarry, comprising 1.3% of the specimens counted (Caron and Jackson, 2008) but only few specimens are known from the Raymond and Collins Quarries.

Maximum Size:
23 mm

Ecology:

Life habits: Common
Feeding strategies: Common
Ecological Interpretations:

Yohoia is thought to have used its three pairs of cephalic appendages, and possibly the biramous limb on the first body segment, to walk on the sea floor. The animal could also swim by waving the flap-like appendage on the body trunk. The setae on these appendages may have been used for respiration. The pair of frontal appendages were likely used to capture prey or scavenge food particles from the sea floor.

References:

BRIGGS, D. E. G. AND R. A. FORTEY. 1989. The early radiation and relationships of the major arthropod groups. Science, 246: 241-243.

BUDD, G. E. 2002. A palaeontological solution to the arthropod head problem. Nature, 417: 271-275.

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

CHEN, J. Y., D. WALOSZEK AND A. MAAS. 2004. A new ‘great-appendage’ arthropod from the Lower Cambrian of China and homology of chelicerate chelicerae and raptorial antero-ventral appendages. Lethaia, 37: 3-20.

COTTON, T. J. AND S. J. BRADDY. 2004. The phylogeny of arachnomorph arthropods and the origin of the Chelicerata. Transactions of the Royal Society of Edinburgh: Earth Sciences, 94: 169-193.

EDGECOMBE, G. D. 2010. Arthropod phylogeny: An overview from the perspectives of morphology, molecular data and the fossil record. Arthropod Structure and Development, 39: 74-87.

HOU, X. AND J. BERGSTRÖM. 1997. Arthropods of the Lower Cambrian Chengjiang fauna, southwest China. Fossils and Strata, 45: 1-116.

SIMONETTA, A. M. 1970. Studies on non trilobite arthropods of the Burgess Shale (Middle Cambrian). Palaeontographia Italica, 66 (New series 36): 35-45.

WALCOTT, C. D. 1912. Cambrian Geology and Paleontology II. Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithsonian Miscellaneous Collections, 57(6): 145-228.

WHITTINGTON, H. B. 1974. Yohoia Walcott and Plenocaris n. gen. arthropods from the Burges

Other Links:

None

Wiwaxia corrugata

3D animation of Wiwaxia corrugata grazing on Morania confluens.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Common
Phylum: Common
Higher Taxonomic assignment: Unranked clade halwaxiids (stem group molluscs)
Species name: Wiwaxia corrugata
Remarks:

The relationship of Wiwaxia is hotly debated; its similarities to the molluscs have been highlighted (Conway Morris, 1985; Scheltema et al., 2003; Caron et al., 2006; Caron et al., 2007), but Matthew’s original view that it was related to the annelid worms (Matthew, 1899) still finds some adherents (Butterfield, 1990; Conway Morris and Peel, 1995; Butterfield, 2006; 2008). It is also possible that Wiwaxia branched off before the molluscs and annelids diverged (Eibye-Jacobsen, 2004). Wiwaxia has recently been placed in a group called the halwaxiids, along with the halkieriids, Orthrozanclus, and Odontogriphus (Conway Morris and Caron, 2007).

Described by: Matthew
Description date: 1899
Etymology:

Wiwaxia – from Wiwaxy Peaks (2,703 m) in Yoho National Park. The word wiwaxy is originally from the Stoney First Nation Nakoda language, meaning “windy.”

corrugata – from the Latin corrugis, “folded, or wrinkled,” in reference to the wrinkled aspect of the sclerites.

Type Specimens: Holotype –ROM8596 in the Royal Ontario Museum, Toronto, Canada.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none described, although sclerites have been reported from a number of Middle Cambrian deposits extending from northern Canada (Butterfield, 1994) to China (Zhao et al., 1994).

Age & Localities:

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

The Walcott and Raymond Quarries on Fossil Ridge. The Trilobite Beds, Tulip Beds (S7) and Collins Quarry on Mount Stephen. Additional smaller localities are known on Mount Field and Mount Odaray.

History of Research:

Brief history of research:

In an early review of fossils collected from the Trilobite Beds on Mount Stephen by Walker, Canadian palaeontologist G. F. Matthew (1899) described several forms he thought represented tubes of various annelid worms, including one he named Orthotheca corrugata. At the time, Matthew did not know this particular fossil was only part of a much larger organism. It was only when Walcott (1911) discovered articulated and much better preserved specimens from the Phyllopod Bed that the morphology of this species became clearer. Walcott placed corrugata in his new genus Wiwaxia and interpreted it as a polychaete annelid worm (Walcott, 1911). The single best specimen of Walker’s “Orthotheca corrugata” remained unrecognized until it was “rediscovered” in the ROM collections in 1977.

Walcott’s interpretation was called into question in a comprehensive reassessment of the genus (Conway Morris, 1985), and Conway Morris’s link between Wiwaxia mouthparts and the molluscan radula was built upon by Scheltema et al. (2003) and Caron et al. (2006). Butterfield (1990), however, defended an annelid affinity mostly based on the study of individual sclerites, first at the crown-, and later at the stem-group level (Butterfield, 2003; 2006), but further work suggested that the evidence does not conclusively support a close relationship with annelids (Eibye-Jacobsen, 2004). A connection with the halkieriids was drawn early on (Bengtson and Morris, 1984; Conway Morris and Peel, 1995), and expanded more recently (Conway Morris and Caron, 2007).

Other studies have dealt more specifically with the ecology and taphonomy of this animal. The finely spaced patterning of ridges on the scale may have given Wiwaxia an iridescent aspect in life (Parker, 1998). Wiwaxia has proven useful in calculating the extent of decay in fossil assemblages (Caron and Jackson, 2006) and in reconstructing the longer term taphonomic processes responsible for the preservation of the Burgess Shale fossils (Butterfield et al., 2007).

Description:

Morphology:

Wiwaxia corrugata is a slug-like organism up to 5.5 cm in length almost entirely covered (except on the ventral surface) with an array of scale-like elements referred to as sclerites and spines. The body is roughly oval, and lacks evidence of segmentation. The body-covering sclerites are arranged in about 50 rows. In addition, two rows of 7–11 blade-like spines are present on the dorsal surface. Spines and sclerites were inserted directly into the body wall. Wiwaxia’s feeding apparatus consists of two (in rare cases three) toothed plates that have been compared to a molluscan radula or annelid jaws.

Abundance:

Wiwaxia is mostly known from the Walcott Quarry where it is relatively common, representing 0.9% of the specimens counted in the community (Caron and Jackson, 2008).

Maximum Size:
55 mm

Ecology:

Life habits: Common
Feeding strategies: Common
Ecological Interpretations:

The similarity of Wiwaxia’s feeding apparatus to that of Odontogriphus suggests that it too fed on the cyanobacterial Morania mats growing on the Cambrian sea floor. Its sclerite armour-plating and long spines, sometimes found broken, suggest that it was targeted by unidentified predators.

References:

BENGSTON, S. AND S. CONWAY MORRIS, 1984. A comparative study of Lower Cambrian Halkieria and Middle Cambrian Wiwaxia. Lethaia, 17:307-329.

BUTTERFIELD, N. J. 1990. A reassessment of the enigmatic Burgess Shale fossil Wiwaxia corrugata (Matthew) and its relationship to the polychaete Canadia spinosa Walcott. Paleobiology: 287-303.

BUTTERFIELD, N. J. 1994. Burgess Shale-type fossils from a Lower Cambrian shallow-shelf sequence in northwestern Canada. Nature, 369(6480): 477-479.

BUTTERFIELD, N. J. 2003. Exceptional fossil preservation and the Cambrian Explosion. Integrative and Comparative Biology, 43:166-177.

BUTTERFIELD, N. J. 2006. Hooking some stem-group “worms”: fossil lophotrochozoans in the Burgess Shale. BioEssays, 28: 1161-1166.

BUTTERFIELD, N. J. 2008. An early Cambrian radula. Journal of Paleontology, 82(3): 543-554.

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

CARON, J.-B., A. H. SCHELTEMA, C. SCHANDER AND D. RUDKIN, 2006. A soft-bodied mollusc with radula from the Middle Cambrian Burgess Shale. Nature, 442(7099): 159-163.

CARON, J.-B., A. H. SCHELTEMA, C. SCHANDER AND D. RUDKIN. 2007. Reply to Butterfield on stem-group “worms:” fossil lophotrochozoans in the Burgess Shale. BioEssays, 29:200-202.

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(1134): 507-582.

CONWAY MORRIS, S. AND J.-B. CARON, 2007. Halwaxiids and the Early Evolution of the Lophotrochozoans. Science, 315(5816): 1255-1258.

CONWAY MORRIS, S. AND J. S. PEEL, 1995. Articulated halkieriids from the Lower Cambrian of North Greenland and their role in early protostome evolution. Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, 347(1321): 305-358.

EIBYE-JACOBSEN, D. 2004. A reevaluation of Wiwaxia and the polychaetes of the Burgess Shale. Lethaia, 37(3): 317-335.

MATTHEW, G. F. 1899. Studies on Cambrian Faunas, No. 3. Upper Cambrian fauna, Mount Stephen, British Columbia. The trilobites and worms. Transactions of the Royal Society, 5: 39-66.

PARKER, A. R. 1998. Colour in Burgess Shale animals and the effect of light on evolution in the Cambrian. Proceedings of the Royal Society B: Biological Sciences, 265(1400): 967.

SCHELTEMA, A. H., K. KERTH AND A. M. KUZIRIAN, 2003. Original molluscan radula: Comparisons among Aplacophora, Polyplacophora, Gastropoda, and the Cambrian fossil Wiwaxia corrugata. Journal of Morphology, 257(2): 219-245.

WALCOTT, C. D. 1911. Middle Cambrian annelids. Smithsonian Miscellaneous Collections, 57(2): 109-144.

ZHAO, Y.-l., Y. QIAN AND X.-S. LI, 1994. Wiwaxia from Early-Middle Cambrian Kaili Formation in Taijiang, Guizhou. Acta Palaeontologica Sinica, 33:359-366.

Other Links:

http://www.paleobiology.si.edu/burgess/wiwaxia.html

Vauxia gracilenta

3D animation of Vauxia bellula and other sponges (Choia ridleyiDiagoniella cyathiformisEiffelia globosaHazelia confertaPirania muricata, and Wapkia elongata) and Chancelloria eros a sponge-like form covered of star-shaped spines.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Common
Phylum: Common
Higher Taxonomic assignment: Demospongea (Order: Verongida)
Species name: Vauxia gracilenta
Remarks:

Vauxia was placed within the hexactinellids by Walcott in his 1920 original description but Rigby (1980) transferred the genus and family to the Demospongea. Demosponges, the same group that are harvested as bath sponges, represent the largest class of sponges today.

Described by: Walcott
Description date: 1920
Etymology:

Vauxia – from Mount Vaux (3,319 m), a mountain Peak in Yoho National Park, British Columbia. The name refers to William Sandys Wright Vaux (1818-1885) an antiquarian at the British Museum.

gracilenta – from the Latin gracilis, “slender,” referring to the delicate structure of the sponge.

Type Specimens: Lectotypes –USNM66515 (V. gracilenta),USNM66508 (V. bellula),USNM66517 (V. densa),USNM66520 (V. venata), in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA. Holotype –ROM53572 (V. irregulara) in the Royal Ontario Museum, Toronto, Canada.
Other species:

Burgess Shale and vicinity: V. bellula Walcott, 1920; V. densa Walcott, 1920; V. irregulara Rigby and Collins, 2004; V. venata Walcott, 1920.

Other deposits: none.

Age & Localities:

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

Burgess Shale and vicinity: Vauxia species are known in the Walcott, Raymond and Collins Quarries on Fossil Ridge, the Trilobite Beds, Tulip Beds (S7) and the Collins Quarry on Mount Stephen, and smaller sites on Mount Field and Odaray Mountain. Vauxia is also known from Monarch in Kootenay National Park.

Other deposits: V. bellula Walcott, 1920 from the Middle Cambrian Wheeler and Marjum Formations in Utah (Rigby et al., 2010); V. magna Rigby, 1980 from the Middle Cambrian Spence Shale in Utah (Rigby, 1980).

History of Research:

Brief history of research:

This sponge was originally described by Walcott in 1920. The genus was reviewed by Rigby (1980) and the species redescribed by Rigby (1986) and Rigby and Collins (2004) in their examination of the Burgess Shale sponges.

Description:

Morphology:

Specimens of Vauxia gracilenta can range from simple unbranched forms to more complex branching forms and reach up to 8 cm in height. Each branch is deeply conical and almost cylindrical, with a simple open central cavity (spongocoel) ending in a rounded of flat opening (osculum). The skeleton is double layered with a thin dermal layer and an inner layer (endosomal). The dermal layer has small openings (ostia) and is composed of a dense network of ladder-like fibers supported by radial fibers from the inner layer. The inner layer forms a regular reticulated net-like skeleton of fibers with 4-6 sided polygons which is characteristic of the genus and species. The fibrous elements (spongin) represent tough collagen proteins. There is no evidence of siliceous spicules in the skeleton.

The different species have been identified mostly based on variations of the skeletal elements and the shape of the branches. Some species can reach up to at least 15 cm in height (V. bellulaV. densa).

Abundance:

Vauxia is relatively common in the Raymond Quarry and other sites on Mount Stephen but is rare in the Walcott Quarry where it represents less than 0.05% of the community (Caron and Jackson, 2008).

Maximum Size:
80 mm

Ecology:

Life habits: Common
Feeding strategies: Common
Ecological Interpretations:

Vauxia 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. 1980. The new Middle Cambrian sponge Vauxia magna from the Spence Shale of Northern Utah and taxonomic position of the Vauxiidae. Journal of Paleontology, 54(1): 234-240.

RIGBY, J. K. 1986. Sponges of the Burgess Shale (Middle Cambrian), British Columbia. Palaeontographica Canadiana, 2: 1-105 p.

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.

RIGBY, J. K., S. B. CHURCH AND N. K. ANDERSON. 2010. Middle Cambrian Sponges from the Drum Mountains and House Range in Western Utah. Journal of Paleontology, 84: 66-78.

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

Other Links:

None

Sidneyia inexpectans

3D animation of Sidneyia inexpectans.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Common
Phylum: Common
Higher Taxonomic assignment: Unranked clade (stem group arthropods)
Species name: Sidneyia inexpectans
Remarks:

Sidneyia is usually considered to be closely related to the chelicerates, but its exact position relative to this group remains unclear (Budd and Telford, 2009). Sidneyia has been variously placed as the sister group to the chelicerates (Hou and Bergström, 1997), close to the crown on the chelicerate stem lineage (Bruton, 1981; Edgecombe and Ramsköld, 1999; Hendricks and Lieberman, 2008), or basal in the chelicerate stem lineage (Briggs and Fortey, 1989; Wills et al., 1998; Cotton and Braddy, 2004).

Described by: Walcott
Description date: 1911
Etymology:

Sidneyia – after Walcott’s son Sidney, who discovered the first specimen in August of 1910.

inexpectans – from the Latin inexpectans, “unexpected,” since Walcott did not expect to find such a fossil in strata older than the Ordovician.

Type Specimens: Lectotype –USNM57487 (S. inexpectans) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: A single specimen from the Chengjiang Fauna in China was used to describe a second species, Sidneyia sinica (Zhang et al. 2002), however this was later shown to be incorrectly attributed to Sidneyia (Briggs et al. 2008).

Age & Localities:

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

Burgess Shale and vicinity: The Walcott, Raymond and Collins Quarries on Fossil Ridge, Mount Field and Mount Stephen – Tulip Beds (S7) and other smaller localities – Odaray Mountain and Stanley Glacier.

Other deposits: Sidneyia has been described from the Wheeler Formation (Briggs and Robison, 1984) and the Spence Shale (Briggs et al. 2008) in Utah, and the Kinzers Formation in Pennsylvania (Resser and Howell, 1938).

History of Research:

Brief history of research:

Sidneyia was the first fossil to be described by Walcott (1911) from the Burgess Shale. Further details were added by Walcott the following year (Walcott, 1912), and Strømer (1944) and Simonetta (1963) made minor revisions to Walcott’s reconstruction. A large appendage found in isolation was originally suggested to be the large frontal appendage of Sidneyia (Walcott, 1911), but this was later found to belong to the anomalocaridid Laggania (Whittington and Briggs, 1985). A major study by Bruton (1981) redescribed the species based on the hundreds of available specimens.

Description:

Morphology:

Sidneyia has a short, wide head shield that is convexly domed and roughly square. The two front lateral corners are notched to allow an antenna and a stalked eye to protrude. Other than the pair of antennae, which are long and thin with at least 20 segments, there are no cephalic appendages. The hemispherical and highly reflective eyes are above and posterior to the antennae.

The thorax of Sidneyia has nine wide, thin body segments that widen from the first to the fourth segment and then get progressively narrower posteriorly. The first four thoracic segments bear appendages with a large, spiny basal segment (the coxa) and 8 thinner segments, ending in a sharp claw. The next five thoracic appendages have a similar appendage but also have flap-like filaments in association with the limbs.

The abdomen consists of three circular rings that are much narrower than the thorax, with a terminal, triangular telson. The last segment of the abdomen has a pair of wide flaps that articulate with the telson to form a tail fan. A trace of the straight gut can be seen in some specimens extending from the anterior mouth to the anus on the telson, and pieces of broken trilobites are sometimes preserved in the gut.

Abundance:

Sidneyia is a relatively common arthropod in the Walcott Quarry, comprising 0.3% of the specimens counted (Caron and Jackson, 2008). Hundreds of specimens have been collected from the Walcott Quarry (Bruton, 1981) and in other nearby localities.

Maximum Size:
160 mm

Ecology:

Life habits: Common
Feeding strategies: Common
Ecological Interpretations:

Sidneyia walked and swam above the sea floor. Its anterior four thoracic appendages were used for walking, and the spiny basal coxa would crush food items and move them towards the mouth. The posterior five thoracic appendages were used for swimming, with the flap-like filaments undulating through the water column to create propulsion. These filaments were also likely used for breathing, like gills.

The predatory nature of Sidneyia is indicated by its spiny coxa used to masticate food, and the presence of crushed fossil debris in its gut. Sidneyia would have walked or swam above the sea floor, using its eyes and antennae to seek out prey, which it would capture and crush with its anterior appendages.

References:

BRIGGS, D. E. G. AND R. A. FORTEY. 1989. The early radiation and relationships of the major arthropod groups. Science, 246: 241-243.

BRIGGS, D. E. G. AND R. A. ROBISON. 1984. Exceptionally preserved non-trilobite arthropods and Anomalocaris from the Middle Cambrian of Utah. The University of Kansas Paleontological Contributions, 111: 1-24.

BRIGGS, D. E. G., B. S. LIEBERMAN, J. R. HENDRICKS, S. L. HALGEDAHL AND R. D. JARRARD. 2008. Middle Cambrian arthropods from Utah. Journal of Paleontology, 82(2): 238-254.

BRUTON, D. L. 1981. The arthropod Sidneyia inexpectans, Middle Cambrian, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London B, 295: 619-653.

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http://paleobiology.si.edu/burgess/sidneyia.html