The Burgess Shale

Hallucigenia sparsa

3D animation of Hallucigenia sparsa.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Class: Xenusia (Order: Scleronychophora, stem group onychophorans)
Remarks:

Hallucigenia is regarded as a member of the “lobopodans,” a group of vermiform Cambrian organisms possessing pairs of leg-like extensions of the body. The affinities of these animals are controversial; they have been placed at the base of a clade comprised of anomalocaridids and arthropods (Budd, 1996), or in a stem-group to modern onychophorans (Ramsköld and Chen, 1998).

Species name: Hallucigenia sparsa
Described by: Walcott
Description date: 1911
Etymology:

Hallucigenia – from the Latin hallucinatio, “wandering of the mind,” after the bizarreness of the animal.

sparsa – from the Latin sparsus, “rare, or scattered,” reflecting the rarity of the specimens available in the original study.

Type Specimens: Holotype –USNM83935 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: H. fortis from the Middle Cambrian Chengjiang biota (Hou and Bergström 1995).

Age & Localities:

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

The Walcott and Raymond Quarries on Fossil Ridge. The Tulip Beds (S7) on Mount Stephen.

History of Research:

Brief history of research:

Hallucigenia was originally described as “Canadia sparsa” by Walcott (1911) in a review of various Burgess Shale “annelids.” One specimen was illustrated twenty years later (Walcott, 1931), but the first thorough study of this animal wasn’t published until Conway Morris (1977) demonstrated that it did not belong to the genus Canadia or to the annelids at all. His reconstruction showed a bizarre animal walking on spines, with dorsal tentacles interpreted as a feeding apparatus (Conway Morris, 1977). The new genus name Hallucigenia was coined in reference to this “dreamlike” appearance and also reflected the organism’s uncertain affinities. It was later shown that the supposed tentacles represented just one row of paired “legs” – the others were buried under a layer of rock and the paired spines were on the dorsal surface (Ramsköld and Hou, 1991, Ramsköld, 1992). The anteroposterior orientation was also reversed, with the former head interpreted as possible decay fluids seeping from the body (Ramsköld, 1992).

Description:

Morphology:

Hallucigenia has a worm-like body with a small head at the end of a long neck; the trunk bears seven pairs of long dorsal spines and seven pairs of slender leg-like lobes. The spacing between lobes and spines is relatively constant. The spine pairs are shifted forward so that the posterior pair of legs does not have a corresponding pair of spines above. Each leg terminates in a pair of claws and the rigid spines have inflexible basal plates. The neck area bears two or three pairs of very fine anterior “appendages” lacking terminal claws. The head is indistinct but the mouth is anterior; a straight gut ends in a posterior anus. It is possible the posterior end is in fact more bulbous than previously thought.

Abundance:

About thirty specimens were studied by Conway Morris (1977). Overall, Hallucigenia is rare, and in the Walcott Quarry it represents 0.19% of the specimens counted in the community (Caron and Jackson, 2008).

Maximum Size:
30 mm

Ecology:

Ecological Interpretations:

Hallucigenia is often found in association with the sponge Vauxia and other organic debris. This co-occurrence has led to suggestions that Hallucigenia fed on sponges, using its clawed legs to hang on, with its spines protecting it from predation. It is also possible that Hallucigenia scavenged on decaying animal remains.

References:

BUDD, G. E. 1996. The morphology of Opabinia regalis and the reconstruction of the arthropod stem-group. Lethaia, 29: 1-14.

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. A new metazoan from the Burgess Shale of British Columbia. Palaeontology, 20: 623-640.

CONWAY MORRIS, S. 1999. The crucible of creation: the Burgess Shale and the rise of animals. Oxford University Press, USA.

HOU, X. AND J. A. N. BERGTRÖM. 1995. Cambrian lobopodians – ancestors of extant onychophorans? Biological Journal of the Linnean Society, 114(1): 3-19.

RAMSKÖLD, L. 1992. The second leg row of Hallucigenia discovered. Lethaia, 25(2): 221–224.

RAMSKÖLD, L. AND X. HOU. 1991. New early Cambrian animal and onychophoran affinities of enigmatic metazoans. Nature, 351: 225-228.

RAMSKÖLD, L. AND J. Y. CHEN. 1998. Cambrian lobopodians: morphology and phylogeny, p. 107-150. In G. D. Edgecombe (ed.), Arthropod fossils and phylogeny. Volume 29. Columbia University Press, New York.

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

WALCOTT, C. 1931. Addenda to descriptions of Burgess Shale fossils. Smithsonian Miscellaneous Collections, 85(3): 1-46.

Other Links:

Habelia? brevicauda

Habelia? brevicauda (USNM 144910) – Holotype. Complete individual preserved without appendages. Total specimen length = 50 mm. Specimen dry – polarized light. Walcott Quarry.

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

Taxonomy:

Class: Unranked clade (stem group arthropods)
Affinity:

Habelia? brevicauda is too poorly known to definitively determine its affinities. It has been aligned in some studies with the arachnomorphs (a group including chelicerates and trilobites), and has been suggested to be closely related to lamellipedians such as Naraoia and the trilobites (Briggs and Fortey, 1989), or placed within Megacheira as a close relative of Leanchoilia (Wills et al., 1998).

Species name: Habelia? brevicauda
Described by: Simonetta
Description date: 1964
Etymology:

Habelia – from Mount Habel (3,161 m), today known as Mount Des Poilus, at the head of Yoho Valley, named in 1900 by Norman Collie in honour of Jean Habel, a German mountaineer. The name Mount Habel is now applied to a peak north of Mount Des Poilus.

brevicauda – from the Latin brevis, “short,” and cauda, “tail.”

Type Specimens: Holotype –USNM144910 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: Habelia optata from Walcott Quarry, Fossil Ridge and The Monarch in Kootenay National Park.

Other deposits: none.

Age & Localities:

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

The Walcott and Raymond Quarries on Fossil Ridge.

History of Research:

Brief history of research:

Habelia optata was first described by Walcott in 1912, to which Simonetta added the possible second species Habelia? brevicauda in 1964. This second species was later restudied by Whittington (1981). Phylogenetic analyses suggest a position within the arachnomorphs (Briggs and Fortey, 1989; Wills et al., 1998). If this is confirmed, Habelia probably represent a stem group of the Mandibulata, which includes crustaceans, myriapods, and hexapods (Scholtz and Edgecombe, 2006).

Description:

Morphology:

The body ranges in size from 1.8 – 5.4 cm and consists of a half-circle head shield and a trunk with twelve segments, the last of which bears a posterior spine. The head shield is smooth and featureless. The trunk segments have a broad, convex axial region, with blade-shaped elements (pleura) extending from either side. The pleura are short and round at the anterior of the body, but become progressively wider and have increasingly backward-pointing tips towards the posterior. The short, broad posterior spine tapers with a bluntly rounded tip.

In the type species, Habelia optata, the exoskeleton is covered in small tubercules , and appendages include a pair of antennae, two pairs of head appendages that are segmented and branch into two (biramous), and six pairs of possibly gnathobasic biramous trunk appendages (i.e., with a robust and spiny basal podomere or segment used for crushing food items). Tubercules and appendages have not been described in Habelia? brevicauda, which is why its placement in the genus is uncertain.

Abundance:

Habelia? brevicauda was originally described from fewer than ten specimens.

Maximum Size:
54 mm

Ecology:

Ecological Interpretations:

Habelia? brevicauda is assumed to have walked on trunk limbs, using its head appendages to manipulate food items. If gnathobases were present, they may have served to masticate food. The frontal antennae were presumably sensory. Considerable flexure of the head may have been possible, which may have allowed Habelia to use its cephalon to dig into the sediment in search of food. It walked along the sea floor while digging and scavenging food items.

References:

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

ELLIOTT, D. K. AND D. L. MARTIN. 1987. A new trace fossil from the Cambrian Bright Angel Shale, Grand Canyon, Arizona. Journal of Paleontology, 61: 641-648.

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.

SIMONETTA, A. M. 1964. Osservazioni sugli artropodi non trilobiti della ‘Burgess Shale’ (Cambriano medio). III conributo. Monitore Zoologico Italiano, 72: 215-231.

WALCOTT, C. D. 1912. Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithsonian Miscellaneous Collections, 57: 145-228.

WILLS, M. A., D. E. G. BRIGGS, R. A. FORTEY, M. WILKINSON AND P. H. A. SNEATH. 1998. An arthropod phylogeny based on fossil and recent taxa, p. 33-105. In G. D. Edgecombe (ed.), Arthropod fossils and phylogeny. Columbia University Press, New York.

WHITTINGTON, H. B. 1981. Rare arthropods from the Burgess Shale, Middle Cambrian, British Columbia. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences, 292: 329-357.

Other Links:

None

Habelia optata

Reconstruction of Habelia optata.

© Marianne Collins

Taxonomy:

Class: Unranked clade (stem group arthropods)
Remarks:

Habelia optata is an arthropod, but its exact relationships remain poorly understood. It has been aligned in some studies to the arachnomorphs (a group including chelicerates and trilobites), and has either been allied with lamellipedians such as Naraoia and the trilobites (Briggs and Fortey, 1989), or placed within Megacheira as closely related to Leanchoilia (Wills et al., 1998).

Species name: Habelia optata
Described by: Walcott
Description date: 1912
Etymology:

Habelia – from Mount Habel (3,161 m), today known as Mount Des Poilus, at the head of Yoho Valley. Named in 1900 by Norman Collie in honour of Jean Habel, a German mountaineer. The name Mount Habel is now applied to a peak north of Mount Des Poilus.

optata – unspecified; may derive from the Latin optatus, “wish or desire.”

Type Specimens: Holotype –USNM57693 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: Habelia? brevicauda from Walcott Quarry and Raymond Quarry, Fossil Ridge.

Other deposits: none.

Age & Localities:

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

The Walcott and Raymond Quarries on Fossil Ridge.

History of Research:

Brief history of research:

Habelia optata was first described by Walcott in 1912, and a possible second species Habelia? brevicauda was added to the genus by Simonetta in 1964. Habelia was later restudied by Whittington (1981). Habelia has been included in some phylogenetic analyses of arthropod relationships (Briggs and Fortey, 1989; Wills et al., 1998) and unusual zig-zag fossil tracks from the Middle Cambrian of the Grand Canyon have been ascribed to an arthropod similar to Habelia (Elliott and Martin, 1987).

Description:

Morphology:

Habelia optata is unusual in that its entire body is covered in tubercles (small, rounded nodules) that are particularly dense on the head shield and the axis of the body trunk. Its body consists of a convex head shield without eyes, and twelve body tergites with a long, jointed posterior spine projecting from the twelfth segment. The first three tergites have a thick median spine that bore tubercles. The head has a pair of multi-segmented setose antennae at the front, and two pairs of possibly biramous appendages with segmented walking limbs and dark sheets that may be filamentous branches.

The twelve body segments have a thick, blunt median spine on the dorsal surface. The first six body segments have appendages that are segmented and branch into two (biramous), including long stout segmented gnathobasic walking limbs (i.e., with a robust and spiny basal podomere or segment used for crushing food items) and a lobed outer branch with lamellae (small elongated structures) along the margin. The lobes are also present on the posterior segments, but no walking branches are associated with them. The tail is a long spine with a single joint midway along its length.

Abundance:

Extremely rare

Maximum Size:
41 mm

Ecology:

Ecological Interpretations:

Habelia optata probably used its six trunk limbs for walking, reserving the head appendages for manipulating food items. It is likely that the frontal antennae were used to sense the environment since there are no obvious eyes. The size and shape of the posterior margin of the head suggests that there was considerable flexure possible between the head and the body, indicating that Habelia may have dug in the sediment for food items. It lived on the muddy seafloor and was heavily protected against predators by its thick body armor and pointed posterior spine, the latter of which would make it difficult for predators to attack from behind.

References:

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

ELLIOTT, D. K. AND D. L. MARTIN. 1987. A new trace fossil from the Cambrian Bright Angel Shale, Grand Canyon, Arizona. Journal of Paleontology, 61: 641-648.

SIMONETTA, A. M. 1964. Osservazioni sugli artropodi non trilobiti della ‘Burgess Shale’ (Cambriano medio). III conributo. Monitore Zoologico Italiano, 72: 215-231.

WALCOTT, C. D. 1912. Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithsonian Miscellaneous Collections, 57: 145-228.

WILLS, M. A., D. E. G. BRIGGS, R. A. FORTEY, M. WILKINSON AND P. H. A. SNEATH. 1998. An arthropod phylogeny based on fossil and recent taxa, p. 33-105. In G. D. Edgecombe (ed.), Arthropod fossils and phylogeny. Columbia University Press, New York.

WHITTINGTON, H. B. 1981. Rare arthropods from the Burgess Shale, Middle Cambrian, British Columbia. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences, 292: 329-357.

Other Links:

None

Emeraldella brocki

Reconstruction of Emeraldella brocki.

© Marianne Collins

Taxonomy:

Class: Unranked clade (stem group arthropods)
Remarks:

Emeraldella is of uncertain phylogenetic affinity due to the paucity of specimens. It was previously placed in the arachnomorphs, as closely allied either with the chelicerates (Wills et al. 1998; Cotton and Braddy, 2004; Hendricks and Lieberman, 2008) or the trilobites and lamellipedians (Hou and Bergström, 1997; Edgecombe and Ramsköld, 1999; Scholtz and Edgecombe, 2006), but it has also been considered as a stem-lineage euarthropod (Budd, 2002).

Species name: Emeraldella brocki
Described by: Walcott
Description date: 1912
Etymology:

Emeraldella – from Emerald Lake, Peak, Pass, River and Glacier north of Burgess Pass, British Columbia, Canada. Emerald Lake was named by guide Tom Wilson in 1882 for the remarkable deep green colour of the water.

brocki – for Reginald Walter Brock, Director of the Geological Survey of Canada from 1907 to 1914.

Type Specimens: Lectotype –USNM57702 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: Emeraldella sp? from the Marjum Formation, House Range, Utah, USA.

Age & Localities:

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

The Walcott Quarry on Fossil Ridge

History of Research:

Brief history of research:

Emeraldella brocki was first described by Walcott (1912). Bruton and Whittington (1983) restudied the material in detail, clarifying many aspects of the animal’s morphology. One possible specimen of Emeraldella has also been described from the Marjum Formation in Utah (Briggs and Robison, 1984). Further work examining the phylogenetic placement of Emeraldella and the arachnomorphs has been conducted by Hou and Bergström (1997), Wills et al.(1998), Edgecombe and Ramsköld (1999), Budd (2002), Cotton and Braddy (2004), Scholtz and Edgecombe (2006) and Hendricks and Lieberman (2008).

Description:

Morphology:

The body consists of a semicircular head shield, segmented trunk and elongated posterior spine, with total body length (excluding spine and antennae) ranging between 1.1 cm and 6.5 cm. With antennae and spine the entire animal would have reached up to 15 cm in length. The body is convex in cross-section and tapers along the posterior half of the trunk. The head shield is smooth, with no evidence of eyes. A pair of long, flexible antennae consisting of over 110 short segments with bristled junctions is attached to the ventral surface at the front of the head. The mouth is ventral and faces backwards. Behind the antennae are five pairs of biramous limbs with a segmented inner branch and a lobed outer branch. The inner branch has six podomeres, including the gnathobase (a robust and spiny basal podomere or segment used for crushing food items), four adjacent podomeres that also bear spines, and a slender terminal podomere armed with three sharp claws. The outer branch of the biramous limb is broad and has three main lobes with filaments and blades.

The trunk of Emeraldella has eleven broad segments with curved, smooth margins. Each segment has a pair of biramous limbs similar to the ones of the head. Behind the trunk segments are two cylindrical body tergites and a long, tapering posterior spine. A dark band running the length of the trunk and into the base of the posterior spine may be the alimentary canal. In the head region, the alimentary canal is U-shaped as it leads forward and upwards from the backward-facing mouth.

Abundance:

Emeraldella brocki is very rare in the Walcott Quarry (less than 0.01% of the community, Caron and Jackson, 2008).

Maximum Size:
202 mm

Ecology:

Ecological Interpretations:

The inner branches of the biramous limbs were likely used for walking on the sea floor, especially the middle eight or nine limbs, which were longer than the posterior limbs. Spines on the inner margin of the walking limbs could have been used to grasp soft prey items, and the terminal claws would push food towards the ventral gnathobases. These strong spiny plates would then shred the food and pass it along the underside of the body towards the mouth. The antennae were used to explore the environment and search for live prey or carcasses, perhaps by ploughing through the soft sediment. While the head was tilted down in the search for food, the posterior segments of the body and the posterior spine may have flexed upwards for balance. The outer limb lobes likely served as gills for respiration. The animal might have been capable of short bursts of swimming, using its broad outer limb branches to propel itself through the water using a wave-like motion.

References:

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.

BRUTON, D. L. AND H. B. WHITTINGTON. 1983. Emeraldella and Leanchoilia, two arthropods from the Burgess Shale, Middle Cambrian, British Columbia. Philosophical Transactions of the Royal Society of London B, 300: 553-582.

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.

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. AND L. RAMSKÖLD. 1999. Relationships of Cambrian Arachnata and the systematic position of Trilobita. Journal of Paleontology, 73: 263-287.

HENDRICKS , J. R. AND B. S. LIEBERMAN. 2008. Phylogenetic insights into the Cambrian radiation of arachnomorph arthropods. Journal of Paleontology, 82: 585-594.

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

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. 1912. Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithsonian Miscellaneous Collections, 57: 145-228.

WILLS, M. A., D. E. G. BRIGGS, R. A. FORTEY, M. WILKINSON, AND P. H. SNEATH. 1998. An arthropod phylogeny based on fossil and recent taxa. pp. 33-105. In G. D. Edgecombe (ed.), Arthropod Fossils and Phylogeny. Columbia University Press, New York.

Other Links:

None

Liangshanella burgessensis

3D animation of Liangshanella burgessensis.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Class: Unranked clade (Order: Bradoriida, stem group arthropods)
Remarks:

Liangshanella is a bradoriid belonging to the family Svealutidae (Siveter and Williams, 1997). The bradoriids were traditionally compared to other bivalved arthropods, such as Recent ostracods (e.g. Sylvester-Bradley, 1961) and Cambrian phosphatocopids (e.g. Maas et al., 2003). However, they are thought to be in the stem-lineage or in a sister group position relative to the Crustaceans (e.g. Hou et al., 1996; Shu et al., 1999; Hou et al., 2010).

Species name: Liangshanella burgessensis
Described by: Siveter and Williams
Description date: 1997
Etymology:

Liangshanella – from Liangshan, a region in South Shaanxi, China.

burgessensis – from the Burgess Shale. The name is derived from Mount Burgess (2,599 m), a mountain peak in Yoho National Park. Mount Burgess was named in 1886 by Otto Klotz, the Dominion topographical surveyor, after Alexander Burgess, a former Deputy Minister of the Department of the Interior.

Type Specimens: Holotype –USNM272083 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: L. circumbolina from the Flinders Ranges in South Australia; L. liangshanensis, L. rotundata, L. orbicularis, L. yunnanensis and L. baensis from southern China; L. lubrica from the Tongying Formation in Hubei, China; L. sayutinae from the Trans-Baikal area in the Russian Far-East and Greenland; L. birkenmajeri from Antarctica. See references in Siveter and Williams (1997).

Age & Localities:

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

The Walcott and Raymond Quarries on Fossil Ridge.

History of Research:

Brief history of research:

Liangshanella liangshanensis is the type species of this genus and was first described by Huo (1956) from Lower Cambrian rocks of south China. Further species have since been described in China (Zhang, 1974; Li, 1975; Qian and Zhang, 1983; Zhang, 2007), Russia and Greenland (Melnikova, 1988), Australia (Topper et al., in press) and Antarctica (Wrona, 2009). Liangshanella burgessensis from the Burgess Shale was described by Siveter and Williams (1997), and the genus has been included in studies on the biogeography, evolution and affinity of the bradoriids (e.g. Shu and Chen, 1994; Williams et al., 2007).

Description:

Morphology:

Like all bradoriids, Liangshanella burgessensis has a small bivalved carapace with a straight dorsal hinge held together by a band of cuticle. The carapaces range in length from 0.66 mm – 4.25 mm and were soft and unmineralized. The bivalved carapace of L. burgessensis is sub-circular, with the anterior end being slightly narrower than the posterior end. There is a marginal ridge along the lateral surface of the valves. A centrally situated, sub-circular muscle scar composed of numerous small pits can be seen inside the valve. No evidence of soft parts has been found.

Abundance:

Liangshanella burgessensis is known from thousands of specimens and is the most common taxon in the Walcott Quarry (11.8% of the community, Caron and Jackson, 2008).

Maximum Size:
10 mm

Ecology:

Ecological Interpretations:

Liangshanella was likely epibenthic, living on and within the first few metres of the soft muddy seafloor. Like other bradoriids, Liangshanella was probably a deposit feeder, and may have even been scavenging or predating on microscopic non-mineralized animals (Williams et al., 2007). Most specimens of Liangshanella found are empty carapaces, being left over from when the animal moulted its exoskeleton. Bradoriids are extremely common in Cambrian rocks, suggesting they played important roles in recycling nutrients in the seabed (Shu et al., 1999). They were also important food sources for larger animals, as indicated by their common presence in coprolites (e.g. Vannier and Chen, 2005).

References:

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

HOU, X., D. J. SIVETER, M. WILLIAMS, D. WALOSSEK AND J. BERGSTRÖM. 1996. Preserved appendages in the arthropod Kunmingella from the early Cambrian of China: its bearing on the systematic position of the Bradoriida and the fossil record of the Ostracoda. Philosophical Transactions of the Royal Society, B351: 1131-1145.

HOU, X., M. WILLIAMS, D.J. SIVETER, D.J. SIVETER, R.J. ALDRIDGE AND R.S. SANSOM. 2010. Soft-part anatomy of the Early Cambrian bivalve arthropods Kunyangella and Kunmingella: significance for the phylogenetic relationships of Bradoriida. Proceedings of the Royal Society, B277: 1835-1841.

HUO, S. 1956. Brief notes on lower Cambrian Archaeostraca from Shensi and Yunnan. Acta Palaeontologica Sinica, 4: 425-445.

LI, Y. 1975. Cambrian Ostracoda and other new descriptions from Sichuan, Yunnan and Shaanxi. Professional Papers of Stratigraphy and Palaeontology, 2: 37-72.

MAAS, A., D. WALOSZEK AND K.J. MÜLLER. 2003. Morphology, ontogeny and phylogeny of the Phosphatocopina (Crustacea) from the Upper Cambrian “Orsten” of Sweden. Fossils and Strata, 49: 1-238.

MELNIKOVA, L. M. 1988. Nekotoryye bradoriidy (Crustacea) iz botomskogo yarusa vostochnogo Zabaykal’ya. Paleontologicheskiy Zhurnal, 1: 114-117.

QIAN, Y. AND S. ZHANG. 1983. Small shelly fossils from the Xihaoping Member of the Tongying Formation in Fangxian County of Hubei Province and their stratigraphical significance. Acta Palaeontologica Sinica, 22: 82-94

SHU, D. AND L. CHEN. 1994. Cambrian palaeobiogeography of Bradoriida. Journal of Southeast Asian Earth Sciences, 9: 289-299.

SHU, D., J. VANNIER, H. LUO, L. CHEN, X. ZHANG AND S. HU. 1999. Anatomy and lifestyle of Kunmingella (Arthropoda, Bradoriida) from the Chengjiang fossil Lagerstätte (Lower Cambrian, Southwest China). Lethaia, 35: 279-298.

SIVETER, D.J. AND M. WILLIAMS. 1997. Cambrian Bradoriid and Phosphatocopid Arthropods of North America. Special Papers in Palaeontology, 57: 1-69.

SYLVESTER-BRADLEY, P. C. 1961. Archaeocopida, p. Q100-103. In R. C. Moore, and C. W. Pitrat (Eds.), Treatise on Invertebrate Paleontology Part Q, Arthropoda 3, Crustacea, Ostracoda. Geological Society of America and University of Kansas Press, Boulder, Colorado and Lawrence, Kansas.

Other Links:

None

Peronochaeta dubia

Taxonomy:

Peronochaeta dubia (ROM 61133). Complete specimen associated with an indeterminate fossil (top right). Specimen length = 8 mm. Specimen dry – polarized light. Walcott Quarry.

© ROYAL ONTARIO MUSEUM. PHOTO: JEAN-BERNARD CARON

Class: Unranked clade (stem group polychaete)
Remarks:

Peronochaetabears some resemblance to modern polychaetes but it cannot be placed in any extant group (Conway Morris, 1979) suggesting a position as a stem-group polychaete (Eibye-Jacobsen, 2004).

Species name: Peronochaeta dubia
Described by: Walcott
Description date: 1911
Etymology:

Peronochaeta – from the Greek perone, “needle,” and khait, “long hair,” in reference to its bristles.

dubia – from the Latin dubius, “uncertain,” presumably reflecting Walcott’s uncertainty regarding his original classification of this worm as Canadia.

Type Specimens: Lectotype – UNSM 83936a; paralectotype – UNSM 83936d, in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

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

The Walcott Quarry on Fossil Ridge.

History of Research:

Brief history of research:

This annelid worm was originally described as a species of Canadia by Charles Walcott (1911). When Simon Conway Morris (1979) re-examined these fossils, he concluded that the differences between this species and Canadia were too great to be contained within a single genus, and erected the new genus Peronochaeta.

Description:

Morphology:

This worm reached one to two centimetres in length, but its body is only 1 mm wide, or 2 mm wide, if its spines (setae) are included. The worm has approximately 25 segments, each bearing a pair of short lateral projections called parapodia. These are simple (uniramous) and the setae are short. A straight gut runs the length of its body. A pair of tentacles appears to be preserved on the sides of the head, although due to the small size and poor preservation, it is difficult to assert this with confidence.

Abundance:

Peronochaeta was considered one of the rarest annelids from the Burgess Shale but additional material has now been collected from the Walcott Quarry representing 0.03% of the specimens counted in the community (Caron and Jackson, 2008).

Maximum Size:
20 mm

Ecology:

Ecological Interpretations:

On account of the scarcity of material, the ecology of this animal is difficult to ascertain. It may have been a scavenger, and its setae probably assisted in locomotion and perhaps even in burrowing.

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. 1979. Middle Cambrian Polychaetes from the Burgess Shale of British Columbia. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences, 285(1007): 227-274.

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

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

Other Links:

None

Ottoia prolifica

3D animation of Ottoia prolifica.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Class: Unranked clade (stem group priapulids)
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).

Species name: Ottoia prolifica
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:

Period:
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:

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

Oryctocephalus reynoldsi

Oryctocephalus burgessensis (ROM 49962). Complete small individual; a presumed carcass with free cheeks in place. Specimen length = 5.5 mm. Specimen dry – direct light (left) and coated with ammonium chloride sublimate to show details (right). Walcott Quarry talus.

© ROYAL ONTARIO MUSEUM. PHOTOS: JEAN-BERNARD CARON

Taxonomy:

Class: Trilobita (Order: Corynexochida)
Remarks:

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

Species name: Oryctocephalus reynoldsi
Described by: Reed
Description date: 1899
Etymology:

Oryctocephalus – from the Greek oryktos, “dug” or “burrowed,” and kephalos, “head.”

reynoldsi – after Mr. S. H. Reynolds, who collected and donated the type specimen to the Woodwardian Museum of the University of Cambridge (now in the Sedgwick Museum of Earth Sciences).

Type Specimens: Holotype (O. reynoldsi) – SM A1425, Sedgwick Museum of Earth Sciences, University of Cambridge, Cambridge, UK. Holotype S17 (O. burgessensis) –USNM96487, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: Oryctocephalus burgessensis Resser, 1938.

Other deposits: many other species worldwide.

Age & Localities:

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

The Trilobite Beds and smaller localities on Mount Stephen. The Walcott Quarry on Fossil Ridge.

History of Research:

Brief history of research:

The genus Oryctocephalus was established by Charles Walcott in 1886 to include the species O. primus, based on isolated cranidia and pygidia from the Middle Cambrian of Nevada. Reed named and described O. reynoldsi in 1899 from a complete specimen (including the articulated thorax), probably collected at the Mount Stephen Trilobite Beds. In the same year as Reed’s paper appeared, G. F. Matthew also had a publication in press, describing O. walkeri from collections on Mount Stephen. Although minor differences between O. reynoldsiand O. walkeri were noted (Matthew, 1899), they are almost certainly one and the same, and Reed’s name has publication priority. In 1938, Resser erected a new species, O. burgessensis, for specimens from the Walcott Quarry. Rasetti (1951) illustrated O. reynoldsiand O. burgessensis and named another new species, O. matthewi, from both localities. Whittington reassessed the Burgess Shale species of Oryctocephalus in 1995, and found that Rasetti’s O. matthewi was indistinguishable from O. reynoldsi.

Description:

Morphology:

Hard parts: both Oryctocephalus reynoldsi and O. burgessensis are small trilobites, with adult exoskeletons generally 15-20 mm long, excluding pygidial spines. Dorsal shields are ovoid in outline, slightly narrower posteriorly. O. reynoldsi has a broad semicircular cephalon, with the genal angles drawn out and back into long slender spines extending almost to the pygidium. The distinctive glabella widens slightly forwards to a rounded front at the anterior border. Three pairs of pits lie forward of the occipital ring, just inside the axial furrows; the posterior pair is joined by a shallow transverse furrow. Faint eye ridges swing back from near the front of the glabella to the long crescentic eye lobes far out on the cheeks. The thorax contains seven wide segments with strong, curving pleural furrows and long terminal spines directed obliquely rearward. The unmistakable pygidium is semicircular, narrower than the cephalon, with a tapering axis of five rings and a terminal piece ending well inside the posterior margin. Six radially disposed pleurae all end in spines, the fourth pair being much broader at the base and very long, directed out and back to at least twice the length of the pygidium. The short fifth and sixth spine pairs extend straight back. O. burgessensis can be distinguished mainly by its subtly shorter genal and fourth pygidial spines; the genal spine also appears to arise slightly farther forward than in O. reynoldsi.

Unmineralized anatomy: not known

Abundance:

Rare, both on Mount Stephen and on Fossil Ridge.

Maximum Size:
25 mm

Ecology:

Ecological Interpretations:

Very similar species of Oryctocephalus are found in Middle Cambrian rocks of deeper water origin in many places around the world, suggesting that these cosmopolitan trilobites typically inhabited open ocean settings.

References:

MATTHEW, G. F. 1899. Studies on Cambrian faunas, No. 3. Upper Cambrian Fauna of Mount Stephen, British Columbia: The trilobites and worms. Transactions of the Royal Society of Canada, Series 2, Vol. 5, Section IV: 39-66.

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

REED, F. R. C. 1899. Woodwardian Museum Notes: a new trilobite from Mount Stephen, Field, B.C. Geological Magazine, New Series (Decade 4), 6: 358-361.

RESSER, C. E. 1938. Fourth contribution to nomenclature of Cambrian fossils. Smithsonian Miscellaneous Collections, 97: 1-43.

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. 1886. Second contribution to the studies on the Cambrian faunas of North America. Bulletin of the US Geological Survey, 30: 1-255.

WHITTINGTON, H. B. 1995. Oryctocephalid trilobites from the Cambrian of North America. Palaeontology, 38: 543-562.

Other Links:

None

Caryosyntrips serratus

Caryosyntrips serratus (ROM 57161) – Holotype, part and counterpart. Individual claw. Specimen length = 78 mm. Specimen dry – direct light (top row), dry – polarized light (bottom row). Walcott Quarry.

© Royal Ontario Museum. Photo: Jean-Bernard Caron

Taxonomy:

Class: Dinocarida (Order: Radiodonta, stem group arthropods)
Remarks:

Caryosyntrips is an anomalocaridid. Anomalocaridids have been variously regarded as basal stem-lineage euarthropods (e.g., Daley et al., 2009), basal members of the arthropod group Chelicerata (e.g., Chen et al., 2004), and as a sister group to the arthropods (e.g., Hou et al., 2006).

Species name: Caryosyntrips serratus
Described by: Daley and Budd
Description date: 2010
Etymology:

Caryosyntrips – from the Greek karyon meaning “nut,” and syntrips, a mythical fiend who smashed pottery; thus, a nut smasher, referring to the nutcracker-like morphology of the paired appendages

serratus – from the Latin serratus, “saw-edged.”

Type Specimens: Holotype –ROM57161 in the Royal Ontario Museum, Toronto, Canada.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

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

The Walcott and Raymond Quarries on Fossil Ridge. Also known from the Tulip Beds (S7) on Mount Stephen.

History of Research:

Brief history of research:

This genus was first noticed and illustrated as “Dinocarida A” in Caron (2005), and formally designated as Carysyntrips serratus by Daley and Budd (2010).

Description:

Morphology:

This taxon is known from eleven specimens of isolated appendages. Appendages are straight and tapering in outline, with a length that ranges between 58 mm and 114 mm. Segmentation of the appendage is poor, but at least 12 podomeres (segments) can be distinguished. The appendage is straight and rigid, with no movement occurring at the podomere boundaries. Each podomere has one thick, short spine on the inner surface, and several smaller spines on the outer surface, giving this outer margin a serrated appearance. The distal end of the appendage tapers to a point, and a single terminal spine is slightly curved. Most appendages are isolated, but a single paired specimen shows the appendages arranged in close proximity, with their thick spine margins in opposition. This particular specimen is loosely associated with potential remains of the body of the animal in the form of some cuticular elements. However, these elements are poorly preserved and might not be of the same animal.

Abundance:

Carysyntrips serratus is extremely rare. Most specimens (8) come from the Walcott Quarry.

Maximum Size:
114 mm

Ecology:

Ecological Interpretations:

Carysyntrips serratus is assumed to have had a similar mode of life to the rest of the anomalocaridids, meaning that it swam through the water column actively searching out prey. Its predatory nature is inferred from the morphology of the appendages, which were heavily spined. The straight, rigid appendages may have pivoted at their proximal attachment points to bring the thick-spine edges of the pair appendages together in a grasping or slicing motion.

References:

CARON, J. B. 2005. Taphonomy and community analysis of the Middle Cambrian Greater Phyllopod Bed, Brugess Shale. Unpublished Ph.D. thesis, University of Toronto, Toronto, 316 pp.

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.

DALEY, A. C., G. E. BUDD, J. B. CARON, G. D. EDGECOMBE AND D. COLLINS. 2009. The Burgess Shale anomalocaridid Hurdia and its significance for early euarthropod evolution. Science, 323: 1597-1600.

DALEY, A. C. AND G. E. BUDD. 2010. New anomalocaridid appendage from the Burgess Shale, Canada. Palaeontology, 53: 721-738.

Other Links:

None

Opabinia regalis

3D animation of Opabinia regalis.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Class: Dinocarida (Order: Radiodonta, stem group arthropods)
Remarks:

Opabinia is an anomalocaridid. Anomalocaridids have been variously regarded as basal stem-lineage euarthropods (e.g., Budd, 1996; Zhang and Briggs, 2007, Daley et al., 2009), basal members of the arthropod group Chelicerata (e.g., Chen et al., 2004), and as a sister group to the arthropods (e.g., Hou et al., 2006)

Species name: Opabinia regalis
Described by: Walcott
Description date: 1912
Etymology:

Opabinia – from Opabin Pass (2,606 m) between Mount Hungabee and Mount Biddle in Yoho National Park. From the Stoney First Nation Nakoda word for “rocky,” a descriptive name for the pass given by Samuel Allen in 1894.

regalis – from the Latin regalis, “royal, or regal.”

Type Specimens: Lectotype –USNM57683 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

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

The Walcott and Raymond Quarries on Fossil Ridge.

History of Research:

Brief history of research:

Opabinia regalis was first described by Walcott (1912) as the most primitive of all Burgess Shale arthropods. Owing to its unique morphology with a bizarre frontal “nozzle,” Opabinia became a flagship fossil for the Burgess Shale, leading to much speculation on its affinity and lifestyle. One famous reconstruction shows the animal swimming upside down as an anostracan crustacean (Hutchinson, 1930).

It wasn’t until the major redescription by Whittington (1975) that the morphology of Opabinia was revealed to be truly one of the most enigmatic of all fossils. It was so unusual, in fact, that when Whittington showed an early version of his reconstruction in a meeting of palaeontologists in 1972, the whole room burst out laughing!

Further work by Bergström (1986) identified similarities between Opabinia and the recently discovered whole-body specimens of Anomalocaris (Whittington and Briggs, 1985), and updated the morphology of the gills and frontal proboscis. Budd (1996) was the first to place Opabinia in the stem lineage of the euarthropods (just below the anomalocaridids), and also suggested the animal had trunk limbs, though this idea was contested by Zhang and Briggs (2007). The issue of whether Opabinia had trunk limbs remains controversial (Budd and Daley, 2011).

Description:

Morphology:

Opabinia has five eyes, a frontal “nozzle,” or proboscis, a body with serially repeated lateral lobes and gills, and a prominent tail fan. The whole body length ranges between 4.3 and 7.0 cm (excluding proboscis). The head has a rounded anterior margin, with five bulbous compound eyes on short stalks clustered on the dorsal surface of the head. The annulated frontal proboscis is four times longer than the head. It is highly flexible, and has a fused pair of appendages at the distal end, consisting of two opposing claws with five or six spines each. The mouth was ventral and faced to the rear.

The trunk was divided into 15 segments, each bearing a pair of lateral lobes in association with gill structures consisting of a series of lanceolate blades. There is some controversy as to the exact location of the gills (dorsal, ventral or posterior) relative to the lobes. The tail fan consists of three pairs of upward-directed flaps. The central region of the body shows an outline of the main body cavity, and a dark line representing a trace of the gut runs along the length of the body, starting with a U-shaped bend near the rearward opening ventral mouth. Paired spherical structures next to the alimentary canal could represent gut glands. There are also controversial triangular features in the central region of the body, which have alternatively been interpreted as lobopod-like walking limbs (Budd, 1996), or as undifferentiated diverticula or extensions of the gut (Whittington, 1975; Zhang and Briggs, 2007).

Abundance:

Opabinia is rare, with only 42 specimens known from all collections. In the Walcott Quarry, Opabinia represents only 0.006% of the community (Caron and Jackson, 2008).

Maximum Size:
101 mm

Ecology:

Ecological Interpretations:

Opabinia was a swimmer. Undulatory waves along its lateral lobes propelled it forward, while it used its tail fan to steer. Opabinia probably employed the distal claws on its flexible nozzle to grasp soft food items and carry them towards its ventral mouth.

References:

BERGSTRÖM, J. 1986. Opabinia and Anomalocaris, unique Cambrian ‘arthropods.’ Lethaia, 19: 241-46.

BUDD, G.E. 1996: The morphology of Opabinia regalis and the reconstruction of the arthropod stem group. Lethaia, 29: 1-14.

BUDD, G.E. AND A. DALEY. 2011. The lobes and lobopods of Opabinia regalis from the middle Cambrian Burgess Shale. Lethaia, DOI: 10.1111/j.1502-3931.2011.00264.x.

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

HUTCHINSON, G.E. 1930. Restudy of some Burgess Shale fossils. Proceedings of the U.S. National Museum, 78: 1-11.

WALCOTT, C. D. 1912. Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata. Smithsonian Miscellaneous Collections, 57: 145-228.

WHITTINGTON, H.B. 1975. The enigmatic animal Opabinia regalis, Middle Cambrian, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London, Series B: Biological Sciences, 271: 1-43.

WHITTINGTON, H. B. AND D. E. G. BRIGGS. 1985. The largest Cambrian animal, Anomalocaris, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London Series B-Biological Sciences, 309: 569-609.

ZHANG, X.-G. AND D. E. G. BRIGGS. 2007: The nature and significance of the appendages of Opabinia from the Middle Cambrian Burgess Shale. Lethaia, 40: 161-173.

Other Links:

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