The Burgess Shale

Nereocaris exilis

Nereocaris briggsi, holotype ROMIP 62153

Taxonomy:

Kingdom: Collins Quarry
Phylum: Collins Quarry
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: Collins Quarry
Feeding strategies: Collins Quarry
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.
Other Links:

Loricicaris spinocaudatus

Loricicaris spinocaudatus, paratype, ROMIP 43188

Taxonomy:

Kingdom: Collins Quarry
Phylum: Collins Quarry
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: Collins Quarry
Feeding strategies: Collins Quarry
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.
Other Links:

Collinsovermis monstruosus

Collinsovermis monstruosus, holotype ROMIP 52703

Taxonomy:

Kingdom: Collins Quarry
Phylum: Collins Quarry
Higher Taxonomic assignment: Order Luolishaniida, Family Collinsovermidae
Species name: Collinsovermis monstruosus
Remarks:

Collinsovermis is one of a variety of lobopodian taxa from the Cambrian, which are early members of the lineage that gave rise to arthropods, and whose only modern survivors are onychophorans (velvet worms) and tardigrades (water bears). Lobopodians characteristically have annulated, unjointed bodies and bear soft limbs after which they are called: the lobopods. Collinsovermis is an armoured member of the Order Luolishaniida, along with forms such as Collinsium and Luolishania from China, or Acinocricus from Utah—together forming the family Collinsovermidae. Luolishaniids are characterized by their thin spines arranged in chevrons and the differentiation of their body into functional regions for suspension-feeding (Caron & Aria 2017, 2020).

Described by: Caron and Aria
Description date: 2020
Etymology:

Collinsovermis – Collins, patronymic, honours its discoverer, Desmond Collins, and vermis is Latin for worm.

monstruosus – From the Latin, in reference to the nickname ‘Collins’ monster’, first introduced by Delle Cave & Simonetta (1991).

Type Specimens: Holotype: ROMIP 52703, Paratypes: ROMIP 52704 and 52705 at the Royal Ontario Museum, Toronto, Canada.
Other species:

Burgess Shale and vicinity: None.
Other deposits: None.

Age & Localities:

Age:
Middle Cambrian, Wuliuan stage, Bathyuriscus-Elrathina Zone of the Burgess Shale Formation (approximately 507 million years old).
Principal localities:

Mount Stephen

History of Research:

Brief history of research:

Collected by a Royal Ontario Museum expedition on Mount Stephen in 1983, the Collinsovermis animal was first revealed, unnamed and undescribed, in the non-peer-reviewed magazine Rotunda (former name of the Royal Ontario Museum Magazine), as a single picture of the holotype, with the caption: “What is it? This new spiny animal (4 cm) with hairy legs has a body plan that has not been seen before.” In 1991, Italian scientists Delle Cave and Simonetta (1991) provided a brief description of the taxon and attempted a reconstruction solely based on the photograph provided by Collins in the Rotunda magazine, coining it the “Collins’ monster”. Despite the lack of name and good documentation, the Collins’ monster have repeatedly featured in studies tackling lobopodian evolution and phylogeny (e.g., Ramsköld & Chen 1998; Budd 2001; Ou et al. 2011; Caron & Aria 2017). It was only in 2020 that the animal was formally named Collinsovermis monstruosus, in honour of Desmond Collins, and fully described based on high resolution pictures of all available material (Caron & Aria 2020).

Description:

Morphology:

Collinsovermis has a plump appearance, with an annulated, unjointed body divided into anterior and posterior regions. The entire dorsum of the body is covered in well-developed spines—three short pairs cover the first three somites (“body segments”) behind the head, while triads of longs spines cover the remaining 10 somites. The anterior region bears 6 pairs of elongate lobopods with thin spines arranged in chevrons, and a small head, as a protrusion bearing a pair of sensory filaments as well as a small dorsal plate and a frontal mouth. The posterior region is made ventrally of 8 pairs of stout annulated lobopods ending in strong, single claws.

Abundance:

Like other lobopodians, Collinsovermis is excessively rare. There are only 3 specimens known, all from the Collins Quarry on Mount Stephen (Fletcher & Collins 2003). They are housed at the Royal Ontario Museum, Department of Natural History.

Maximum Size:
32 mm.

Ecology:

Life habits: Collins Quarry
Feeding strategies: Collins Quarry
Ecological Interpretations:

Collinsovermis exemplifies suspension-feeding adaptations in lobopodians associated with strongly-developed defensive elements. Like other members of the order Luolishaniidae, and those of the family bearing its name, this animal was using its stout back limbs for anchoring (probably to sponges) and its slender spinose anterior limbs to sieve organic particles or plankton. The long dorsal spines most certainly served as deterrent to predators.

References:

  • BUDD, G. E. 2001. Tardigrades as ‘stem-group arthropods’: The evidence from the Cambrian fauna. Zoologischer Anzeiger, 240, 265–279.
  • CARON, J. and ARIA, C. 2020. The Collins’ monster, a spinous suspension‐feeding lobopodian from the Cambrian Burgess Shale of British Columbia. Palaeontology, 63, 979–994.
  • CARON, J.-B. and ARIA, C. 2017. Cambrian suspension-feeding lobopodians and the early radiation of panarthropods. BMC Evolutionary Biology, 17, 29.
  • DELLE CAVE, L. and SIMONETTA, A. M. 1991. Early Palaeozoic arthropods and problems of arthropod phylogeny; with some notes on taxa of doubtful affinities. In S, S. A. M. C. M. (ed.) The Early Evolution of Metazoa and the Significance of Problematic Taxa. Proceedings of an International Symposium Held at the University of Camerino 27-31 March 1989, Cambridge University Press, 189–244 pp.
  • 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.
  • OU, Q., LIU, J., SHU, D., HAN, J., ZHANG, Z., WAN, X. and LEI, Q. 2011. A rare onychophoran-like lobopodian from the lower Cambrian Chengjiang Lagerstätte. Journal of Paleontology, 85, 587–594.
  • RAMSKÖLD, L. and CHEN, J. Y. 1998. Cambrian lobopodians: morphology and phylogeny. In EDGECOMBE, G. D. (ed.) Arthropod Fossils and Phylogeny, Columbia University Press, New York, 107–150 pp.
Other Links:

Capinatator praetermissus

Capinatator praetermissus, ROMIP 64247

Taxonomy:

Kingdom: Collins Quarry
Phylum: Collins Quarry
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: Collins Quarry
Feeding strategies: Collins Quarry
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.
Other Links:

Wiwaxia corrugata

3D animation of Wiwaxia corrugata grazing on Morania confluens.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Collins Quarry
Phylum: Collins Quarry
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: Collins Quarry
Feeding strategies: Collins Quarry
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: Collins Quarry
Phylum: Collins Quarry
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: Collins Quarry
Feeding strategies: Collins Quarry
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

Selkirkia columbia

3D animation of Selkirkia columbia.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Collins Quarry
Phylum: Collins Quarry
Higher Taxonomic assignment: Unranked clade (stem group priapulids)
Species name: Selkirkia columbia
Remarks:

Selkirkia has been compared to the nemathelminth worms (Maas et al., 2007), but most analyses support a relationship with the priapulids at a stem-group level (Harvey et al., 2010; Wills, 1998).

Described by: Walcott
Description date: 1911
Etymology:

Selkirkia – from the Selkirk Mountains, a mountain range in southeastern British Columbia.

columbia – from British Columbia, where the Burgess Shale is located.

Type Specimens: Holotype –USNM57624 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: The genus Selkirkia ranges from the Lower to the Middle Cambrian and is represented by several species, including S. sinica from the Lower Cambrian Chengjiang Biota (Luo et al., 1999; Maas et al., 2007), S. pennsylvanica from the Lower Cambrian Kinzers Formation (Resser and Howell, 1938), Selkirkia sp. cf. and S. spencei from the Middle Cambrian Spence Shale of Utah (Resser, 1939; Conway Morris and Robison, 1986, 1988), and S. willoughbyi from the Middle Cambrian Marjum Formation of Utah (Conway Morris and Robison, 1986).

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, and smaller localities on Mount Field and Mount Odaray. The Trilobite Beds, the Collins Quarry, the Tulip Beds (S7) and smaller localities on Mount Stephen.

Other deposits: The Middle Cambrian Spence Shale of Utah (Resser, 1939; Conway Morris and Robison, 1986, 1988).

History of Research:

Brief history of research:

Charles Walcott (1908) illustrated a single specimen of a simple tube that he named “Orthotheca major.” He interpreted the fossil as the tube of a polychaete worm, along with another famous species, “O. corrugata,” described by Matthew a decade earlier. O. corrugata is now referred to as Wiwaxia corrugata, which is not the tube of a worm but the scale of an armoured mollusc! The original specimen of “O. major” came from the Trilobite Beds on Mount Stephen, but it was not until the discovery of complete specimens from Fossil Ridge showing soft-bodied worms within the tubes that more details about this animal became available. Walcott (1911) created a new genus name Selkirkia to accommodate the new fossil material. In addition to the type species, S. major, he named two new species, S. gracilis and S. fragilis. In a revision of Walcott’s collections and other fossils discovered by the Geological Survey of Canada, Conway Morris (1977) synonymised Walcott’s three species into one that he called S. columbia, which is still in use today. S. columbia was described as a primitive priapulid worm (Conway Morris, 1977); later studies showed that it belongs to the priapulid stem group (Wills, 1998; Harvey et al., 2010).

Description:

Morphology:

Selkirkia lived in a tube and could reach up to 6 centimetres in length. The body of the worm itself is similar to most priapulids in having a trunk (which remained in the tube) and an anterior mouthpart that could be inverted into the trunk, called a proboscis. The proboscis has different series of spines along its length and is radially symmetrical. Small body extensions called papillae are present along the anterior part of the trunk and probably helped in anchoring the trunk in the tube. The gut is straight and the anus is terminal. The unmineralized tube is slightly tapered, open at both ends, and bears fine transverse lineations.

Abundance:

Selkirkia is the most abundant priapulid in the Walcott Quarry community, representing 2.7% of the entire community (Caron and Jackson, 2008); thousands of specimens are known, mostly isolated tubes.

Maximum Size:
60 mm

Ecology:

Life habits: Collins Quarry
Feeding strategies: Collins Quarry
Ecological Interpretations:

The well developed proboscis and strong spines suggest a carnivorous feeding habit. Comparisons with modern tube-building priapulids suggest Selkirkia was capable of only limited movement, and spend most of the time buried vertically or at an angle to the sediment-water interface, where they might have “trap fed” on live prey. Empty tubes were often used as a substrate for other organisms to colonize, for example, brachiopods, sponges and primitive echinoderms (see Echmatocrinus).

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. 1977. Fossil priapulid worms. Special Papers in Palaeontology, 20: 1-95.

CONWAY MORRIS, S. AND R. A. ROBISON. 1986. Middle Cambrian priapulids and other soft-bodied fossils from Utah and Spain. The University of Kansas paleontological contributions, 117: 1-22.

CONWAY MORRIS, S. AND R. A. ROBISON. 1988. More soft-bodied animals and algae from the Middle Cambrian of Utah and British Columbia. University of Kansas Paleontological Contributions, Paper, 122: 23-48.

HARVEY, T. H. P., X. DONG AND P. C. J. DONOGHUE. 2010. Are palaeoscolecids ancestral ecdysozoans? Evolution & Development, 12(2): 177-200.

LUO, H., S. HU, L. CHEN, S. ZHANG AND Y. TAO. 1999. Early Cambrian Chengjiang fauna from Kunming region, China. Yunnan Science and Technology Press, Kunming, 162 p.

MAAS, A., D. HUANG, J. CHEN, D. WALOSZEK AND A. BRAUN. 2007. Maotianshan-Shale nemathelminths – Morphology, biology, and the phylogeny of Nemathelminthes. Palaeogeography, Palaeoclimatology, Palaeoecology, 254(1-2): 288-306.

RESSER, C. E. AND B. F. HOWELL. 1938. Lower Cambrian Olenellus Zone of the Appalachians. Geological Society of America, Bulletin, 49: 195-248.

RESSER, C. E. 1939. The Spence Shale and its fauna. Smithsonian Miscellaneous Collections, 97(12):1-29.

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

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

WILLS, M. A. 1998. Cambrian and Recent disparity: the picture from priapulids. Paleobiology, 24(2): 177-199.

Other Links:

None

Leptomitus lineatus

Leptomitus undulatus (ROM 53571) – Holotype (part and counterpart). Only known specimen of this species showing partial base, prominent ridges and top part (osculum). Specimen height = 78 mm. Specimen wet – direct light. Walcott Quarry.

© Royal Ontario Museum. Photos: Jean-Bernard Caron

Taxonomy:

Kingdom: Collins Quarry
Phylum: Collins Quarry
Higher Taxonomic assignment: Demospongea (Order: Monaxonida)
Species name: Leptomitus lineatus
Remarks:

Leptomitus is considered a primitive demosponge (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:

Leptomitus – from the Greek lept, “slender,” and mitos, “thread.” This name refers to the overall shape of the sponge.

lineatus – from the Latin lineatus, “streaked.” This refers to the wrinkle appearance of this sponge.

Type Specimens: Lectotype –USNM66448 (L. lineatus) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA. Holotype –ROM53558 (L. undulatus) in the Royal Ontario Museum, Toronto, Canada.
Other species:

Burgess Shale and vicinity: L. undulatus Rigby and Collins 2004 from the Walcott Quarry.

Other deposits: L. zitteli Walcott, 1886 from the Middle Cambrian Parker Slate in Vermont; L. metta Rigby, 1983 from the Middle Cambrian Marjum Formation of Utah; L. conicus García-Bellido et al., 2007 from the Middle Cambrian Murero Formation of Spain; L. teretiusculus Chen, Hou and Lu, 1989 from the Lower Cambrian Chengjiang biota in China (see Rigby and Hou, 1995); unidentified species from the Lower Cambrian Niutitang Formation in China (Yang et al., 2003).

Age & Localities:

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

The Walcott Quarry on Fossil Ridge. The Tulip Beds (S7) and the Collins Quarry on Mount Stephen.

History of Research:

Brief history of research:

Leptomitus was originally described by Charles Walcott (1920) as a new genus “Tuponia” along with several species (T. lineatea, T. flexilis, T. flexilis var. intermedia). This genus was later synonymized by Resser and Howell (1938) with Leptomitus, a genus named by Walcott in 1886. Ribgy (1986) redescribed the Burgess Shale sponges including Leptomitus and considered L. flexilis to be a junior synonym of L. lineatus. Rigby and Collins (2004) added a second species L. undulatus based on new material collected by the Royal Ontario Museum.

Description:

Morphology:

L. lineatus is an elongate tubular sponge with a double-layered skeleton. The outer layer is composed of long monoaxial spicules (simple spicules with pointed ends) arranged vertically along the length of the sponge. The varying thicknesses of these elongate spicules give the sponge a distinctive wrinkly appearance in the fossils. The inner layer is composed of tiny horizontal spicules that form an unclumped thatch; these tufts can be seen at the oscular margin (opening at the top of the sponge). The base of the sponge is rounded in shape and would have had a small holdfast structure. L. undulatus has the same wall structure as L. lineatus but has a rounder goblet shaped skeleton.

Abundance:

L. lineatus is relatively common in the Walcott Quarry and represents 0.26% of the community (Caron and Jackson, 2008). L. undulatus is known from a single specimen.

Maximum Size:
360 mm

Ecology:

Life habits: Collins Quarry
Feeding strategies: Collins Quarry
Ecological Interpretations:

Leptomitus 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.

CHEN, J. Y., X. G. HOU AND H. Z. LU. 1989. Lower Cambrian leptomitids (Demospongea), Chengjiang, Yunnan. Acta Palaeontologica Sinica, 28: 17-31.

GARCÍA-BELLIDO, D. C., R. GOZALO, J. B. CHIRIVELLA MARTORELL AND E. LIÑÁN. 2007. The demosponge genus Leptomitus and a new species from the Middle Cambrian of Spain. . Palaeontology, 50: 467-478.

RESSER, C. F. AND B. F. HOWELL. 1938. Lower Cambrian Olenellus Zone of the Appalachians. Geological Society of American Bulletin, 49: 195-248.

RIGBY, J. K. 1983. Sponges of the Middle Cambrian Marjum Limestone from the House Range and Drum Mountains of Western Millard County, Utah. Journal of Paleontology, 57: 240-270.

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

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.

WALCOTT, C. 1886. Second contribution to the studies on the Cambrian faunas of North America. U.S. Geological Survey Bulletin, 30: 1-369.

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

Other Links:

None

Isoxys acutangulus

3D animation of Isoxys carinatus.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: Collins Quarry
Phylum: Collins Quarry
Higher Taxonomic assignment: Unranked clade (stem group arthropods)
Species name: Isoxys acutangulus
Remarks:

The affinity of Isoxys is uncertain because for a long time it was known only from empty carapaces. Recent descriptions of soft parts show that the frontal appendage is similar to that of some megacheiran, or “great appendage,” taxa such as Leanchoilia, Alalcomenaeus, and Yohoia (Vannier et al., 2009; García-Bellido et al., 2009a). The affinity of Megacheira as a whole is uncertain, but it has been suggested that they either sit within the stem-lineage to the euarthropods (Budd, 2002) or they are stem-lineage chelicerates (Chen et al., 2004; Edgecombe, 2010).

Described by: Walcott
Description date: 1908
Etymology:

Isoxys – from the Greek isos, “equal,” and xystos, “smooth surface”; thus referring to the pair of smooth valves.

acutangulus – from the Latin acutus, “sharp, pointed,” and angulus, “angle”; thus referring to the acute angle of the cardinal spines.

Type Specimens: Type status under review –USNM56521 (I. acutangulus) and Holotype –USNM189170 (I. longissimus) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: I. longissimus from Walcott, Raymond and Collins Quarries on Fossil Ridge.

Other deposits: I. chilhoweanus from the Chilhowee Group, Tennessee, USA; I. auritus, I. paradoxus and I. curvirostratus from the Maotianshan Shale of China; I. bispinatus from the Shuijingtuo Formation, Hubei, China; I. wudingensis from the Guanshan fauna of China; I. communis and I. glaessneri from the Emu Bay Shale of Australia; I. volucris from the Buen Formation, Sirius Passet in Greenland; I. carbonelli from the Sierro Morena of Spain, and I. zhurensis from the Profallotaspis jakutensis Zone of Western Siberia. Undescribed species from Canada; Mount Cap Formation in the Mackenzie Mountains, Northwest Territories and the Eager Formation near Cranbrook. Other undescribed species in the Kaili Formation, Guizhou Province, China and the Kinzers Formation, Pennsylvania, USA. See references in Briggs et al., 2008; García-Bellido et al., 2009a,b; Stein et al., 2010; Vannier and Chen, 2000.

Age & Localities:

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

The Walcott, Raymond and Collins Quarries on Fossil Ridge. Additional localities are known on Mount Field, Mount Stephen – Tulip Beds (S7) and the Trilobite Beds, and near Stanley Glacier.

History of Research:

Brief history of research:

Walcott gave the name Isoxys to specimens from the lower Cambrian Chilhowee Group of Tennessee, USA, in 1890. He then later designated the first species from the Trilobite Beds on Mount Stephen, Anomalocaris? acutangulus (Walcott, 1908), although he placed it erroneously in the genus Anomalocaris. Simonetta and Delle Cave (1975) renamed it Isoxys acutangulus and discovered a second Burgess Shale species, I. longissimus. The original designations were based on carapaces only, making research on the ecology and affinity of Isoxys difficult. Soft parts have recently been described from the Burgess Shale taxa (Vannier et al. 2009, García-Bellido et al. 2009a).

Description:

Morphology:

The most prominent feature of Isoxys is the non-mineralized carapace, which ranged in length from 1 cm to almost 4 cm, and covered most of the body. It was folded to give two equal hemispherical valves, and had pronounced spines at the front and back. A pair of bulbous, spherical eyes protrudes forward and laterally from under the carapace. They are attached to the head by very short stalks. A pair of frontal appendages that are segmented and non-branching (uniramous) is adjacent to the eyes. The flexible appendages are curved with a serrated outline and five segments in total, including a basal part, three segments with stout outgrowths, and a pointed terminal segment.

The trunk of the body has 13 pairs of evenly spaced appendages that are segmented and branch into two (biramous), with slender, unsegmented walking limbs and large, paddle-like flaps fringed with long setae. The telson has a pair of lateral flaps. A cylindrical gut passes from the head to the ventral terminus of the telson, and is lined by paired, lobate gut glands. I. longissimus is distinguished from I. acutangulus by the presence of extremely long spines and an elongated body shape.

Abundance:

Isoxys is known from hundreds of specimens collected on Fossil Ridge. In the Walcott Quarry, Isoxys acutangulus is relatively common and represents about 0.35% of the community whereas Isoxys longissimus is extremely rare (Caron and Jackson, 2008).

Maximum Size:
40 mm

Ecology:

Life habits: Collins Quarry
Feeding strategies: Collins Quarry
Ecological Interpretations:

The streamlined body, thin carapace, and the presence of large paddle-shaped flaps in the appendages all suggest that Isoxys was a free-swimming animal. The spines and wide telson would have been use for steering and stability in the water column. A predatory lifestyle is indicated by the large eyes, frontal appendage, and gut glands. Isoxys would have swum just above the sea floor, seeking out prey in the water column and at the sediment-water interface.

References:

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

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.

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

GARCÍA-BELLIDO, D. C., J. VANNIER AND D. COLLINS. 2009a. Soft-part preservation in two species of the arthropod Isoxys from the middle Cambrian Burgess Shale of British Columbia, Canada. Acta Palaeontologica Polonica, 54: 699-712.

GARCÍA-BELLIDO, D. C., J. R. PATERSON, G. D. EDGECOMBE, J. B. JAGO, J. G. GEHLING AND M. S. Y. LEE. 2009b. The bivavled arthropods Isoxys and Tuzoia with soft-part preservation from the lower Cambrian Emu Bay Shale Lagerstätte (Kangaroo Island, Australia). Palaeontology, 52: 1221-1241.

SIMONETTA, A.M. AND L. DELLE CAVE. 1975. The Cambrian non trilobite arthropods from the Burgess Shale of British Columbia. A study of their comparative morphology, taxonomy and evolutionary significance. Palaeontographia Italica, 69: 1-37.

STEIN, M., J. S. PEEL, D. J. SIVETER AND M. WILLIAMS. 2010. Isoxys (Arthropoda) with preserved soft anatomy from the Sirius Passet Lagerstätte, lower Cambrian of North Greenland. 2010. Lethaia, 43: 258-265.

VANNIER, J. AND J.-Y. CHEN. 2000. The Early Cambrian colonization of pelagic niches exemplified by Isoxys (Arthropoda). Lethaia, 35: 107-120.

VANNIER, J., D. C. GARCÍA-BELLIDO, S. X. HU AND A. L. CHEN. 2009. Arthropod visual predators in the early pelagic ecosystem: evidence from the Burgess Shale and Chengjiang biotas. Proceedings of the Royal Society of London Series B, 276: 2567-2574.

WALCOTT, C. D. 1890. The fauna of the Lower Cambrian or Olenellus Zone. Reports of the U.S. Geological Survey, 10: 509-763.

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

WILLIAM, M., D. J. SIVETER AND J. S. PEEL. 1996. Isoxys (Arthropoda) from the early Cambrian Sirius Passet Lagerstätte, North Greenland. Journal of Paleontology, 70: 947-954.

Other Links:

None

Ottoia prolifica

3D animation of Ottoia prolifica.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Collins Quarry
Phylum: Collins Quarry
Higher Taxonomic assignment: Unranked clade (stem group priapulids)
Species name: Ottoia prolifica
Remarks:

Ottoia has been compared to the nemathelminth worms (Maas et al., 2007), but most analyses support a relationship with the priapulids at a stem-group level (Harvey et al., 2010; Wills, 1998).

Described by: Walcott
Description date: 1911
Etymology:

Ottoia – from Otto Pass (2,106 m), a few kilometres north-west of the Burgess Shale. The pass was named after Otto Klotz, an astronomer working for the Department of the Interior along the Canadian Pacific Railroad (read about Otto Klotz in the section “First Discoveries”)

prolifica – from the Latin proles, “offspring,” and ferax, “rich, fruitful,” in reference to the great number of specimens discovered.

Type Specimens: Lectotype –USNM57619 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none

Other deposits: Ottoia sp. from the Lower Cambrian Pioche Shale, Nevada (Lieberman, 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 and Raymond Quarries on Fossil Ridge, the Collins Quarry, the Tulip Beds (S7) and smaller localities on Mount Stephen. Smaller localities on Mount Field, Mount Odaray and Monarch Cirque.

Other deposits: The same species also occurs in the Middle Cambrian Spence Shale and Marjum Formations, Utah (Conway Morris and Robison, 1986).

History of Research:

Brief history of research:

Charles Walcott (1911) first described Ottoia as a tentative member of the now-dismantled grouping of worms called the Gephyrea, which included the priapulids as well as the sipunculans and echiurans. He emphasized a comparison with the sipunculans, leading some subsequent authors to consider it as a member of this phylum; others, however, suggested affinities with the parasitic acanthocephalans, or the priapulids (Banta and Rice, 1970). A re-analysis of the fossil material itself was not conducted until the 1970s, with work by Banta and Rice (1970) and Conway Morris (1977) supporting a relationship with the priapulids, which was later demonstrated to be at a stem-group level (Wills, 1998). Other work has focussed on the ecology of the Burgess Shale representatives (Bruton, 2001; Vannier, 2009; Vannier et al., 2010).

Description:

Morphology:

Ottoia is a priapulid worm with a tooth-lined mouthpart (proboscis) that could be inverted into the trunk; a short posterior tail extension could also be inverted. Ottoia reached 15 cm in length; the smallest specimens – presumably juveniles, but identical to adults – were just 1 cm long. The proboscis was adorned with 28 rows of hooks interspersed with a variety of spines. The worms are usually found curved into a U-shape, with their sediment-filled guts often visible running down the centre of the organism. The trunk was annulated, and bore two sets of four hooks arranged in a ring towards the rear end; these are the only traces of bilateral symmetry, with a radial symmetry superimposed on the organism. Ottoiaperiodically shed its cuticle to allow growth.

Abundance:

Ottoia is one of the more abundant Burgess Shale organisms, accounting for over 80% of the Walcott Quarry priapulids (Conway Morris, 1977) and over 1.3% of the entire Walcott Quarry community (Caron and Jackson, 2008); thousands of specimens are known.

Maximum Size:
150 mm

Ecology:

Life habits: Collins Quarry
Feeding strategies: Collins Quarry
Ecological Interpretations:

Specimens of Haplophrentis carinatus preserved in the gut indicate that this hyolith was a staple of the Ottoia diet (Conway Morris, 1977). One fossil slab also shows nine specimens feeding on a recently-dead Sidneyia carcass (Bruton, 2001).

References:

BANTA, W. C. AND M. E. RICE. 1970. A restudy of the Middle Cambrian Burgess Shale fossil worm, Ottoia prolifica. International Symposium on the Biology of the Sipuncula and Echiura 2, Kotor: 79-90.

BRUTON, D. L. 2001. A death assemblage of priapulid worms from the Middle Cambrian Burgess Shale. Lethaia, 34(2):163-167.

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. 1977. Fossil priapulid worms. Special Papers in Palaeontology, 20: 1-95.

CONWAY MORRIS, S. AND J. S. PEEL. 2009. New Palaeoscolecidan Worms from the Lower Cambrian: Sirius Passet, Latham Shale and Kinzers Shale. Acta Palaeontologica Polonica, 55(1): 141-156.

HARVEY, T. H. P., X. DONG AND P. C. J. DONOGHUE. 2010. Are palaeoscolecids ancestral ecdysozoans? Evolution & Development, 12(2): 177-200.

MAAS, A., D. HUANG, J. CHEN, D. WALOSZEK AND A. BRAUN. 2007. Maotianshan-Shale nemathelminths – Morphology, biology, and the phylogeny of Nemathelminthes. Palaeogeography, Palaeoclimatology, Palaeoecology, 254(1-2): 288-306.

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

Other Links:

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