The Burgess Shale

Overall Abundance: Abundant

Selkirkia columbia

3D animation of Selkirkia columbia.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Abundant
Phylum: Abundant
Class: 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:

Period:
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: Abundant
Feeding strategies: Abundant
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

Elrathina cordillerae

Elrathina cordillerae (ROM 53273). Complete individual; a presumed carcass with free cheeks in place (coated with ammonium chloride sublimate to show details). Specimen length = 24 mm. Specimen dry – direct light. Mount Stephen Trilobite Beds on Mount Stephen.

© Royal Ontario Museum. Photo: Jean-Bernard Caron

Taxonomy:

Kingdom: Abundant
Phylum: Abundant
Class: Trilobita (Order: Ptychopariida)
Species name: Elrathina cordillerae
Remarks:

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

Described by: Rominger
Description date: 1887
Etymology:

Elrathina – unspecified.

cordillerae – in reference to the Western Cordillera (Canadian Rocky Mountain ranges), derived from the Spanish cordilla, the diminutive of cuerda, meaning “cord.”

Type Specimens: Type status under review – UMMP 4883 (6 specimens), University of Michigan Museum of Paleontology, Ann Arbor, Michigan, USA.
Other species:

Burgess Shale and vicinity: Elrathina parallela, E. brevifrons, E. spinifera, and E. marginalis have been described from similar stratigraphic horizons at nearby sites on Mount Field, Mount Stephen, and Mount Odaray.

Other deposits: Other species of Elrathina have been reported from the Cambrian of North America and Greenland.

Age & Localities:

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

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

History of Research:

Brief history of research:

E. cordillerae was originally described under the genus name Conocephalites in Rominger’s 1887 publication on trilobites from Mount Stephen. In 1888 Walcott reallocated the species to Ptychoparia where it remained until Charles Resser, Walcott’s former assistant at the United States National Museum, established the new replacement genus Elrathina (Resser, 1937). Other workers have subsequently suggested that Elrathina is indistinguishable from Ptychoparella (see Blaker and Peel, 1997).

Species of Elrathina, along with those of the corynexochid Bathyuriscus, were found to be very abundant in a narrow interval of Middle Cambrian rocks throughout western North America, forming the basis of the Bathyuriscus-Elrathina Zone erected by Charles Deiss (1940).

Description:

Morphology:

Hard parts: adult dorsal exoskeletons average about 2 cm long. The semicircular cephalon is about one-third the length of the entire dorsal shield, bordered by a well-defined narrow rim, and with rounded genal angles. Weak transverse eye ridges extend to the small eyes, which are located just forward of cephalic mid-length. The slightly anteriorly narrowing glabella is rounded in front and exhibits three pairs of shallow lateral furrows; the pre-glabellar field is about the same width as the narrow anterior rim. The long, tapering thorax with a narrow axial lobe contains between 17 and 19 straight-sided segments, flexed gently downwards a short distance from the rounded tips. The tiny elliptical pygidium usually features two segments.

Unmineralized anatomy: rare specimens from the Walcott Quarry on Fossil Ridge retain tantalizing evidence of soft parts, including a pair of slender uniramous antennae, followed by very delicate looking biramous limbs beneath the cephalon, thorax and pygidium. These and other individuals of E. cordillerae are occasionally associated with a dark stain adjacent to the exoskeleton, presumably representing fluidized decay products.

Abundance:

Relatively common on Fossil Ridge and locally very abundant in the Walcott Quarry, where it represents about 25% of all trilobites collected (Caron and Jackson, 2008).

Maximum Size:
28 mm

Ecology:

Life habits: Abundant
Feeding strategies: Abundant
Ecological Interpretations:

Like similar-looking ptychoparioid trilobites, E. cordillerae may be interpreted as a fully mobile, epibenthic deposit (particle) feeder adapted to very low oxygen levels.

References:

BLAKER, M. R. AND J. S. PEEL. 1997. Lower Cambrian trilobites from North Greenland. Meddeleser om Grønland, Geoscience, 35, 145 p.

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

DEISS, C. 1940. Lower and Middle Cambrian stratigraphy of southwestern Alberta and southeastern British Columbia. Bulletin of the Geological Society of America, 51: 731-794.

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

RESSER, C. E. 1937. Third contribution to nomenclature of Cambrian trilobites. Smithsonian Miscellaneous Collections, 95(22): 29 p.

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

RUDKIN, D. M. 1989. Trilobites with appendages from the Middle Cambrian Stephen Formation of British Columbia. 28th International Geological Congress, Washington, D.C. July 9-19, 1989. Abstracts: 2-729.

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. 1918. Cambrian Geology and Paleontology IV. Appendages of trilobites. Smithsonian Miscellaneous Collections, 67(4): 115-216.

WALCOTT, C. D. 1924. Cambrian and Lower Ozarkian trilobites. Smithsonian Miscellaneous Collections, 75(2): 53-60.

Other Links:

http://www.trilobites.info/ordptychopariida.htm

http://www.geological-supplies.com/burgess/abstracts/balint

http://gsa.confex.com/gsa/2008AM/finalprogram/abstract_149017.htm

Pagetia bootes

Pagetia bootes (ROM 60756). Complete individual. Specimen length = 4.5 mm. Specimen dry – direct light (left) and coated with ammonium chloride sublimate to show details (right). Walcott Quarry.

© ROYAL ONTARIO MUSEUM. PHOTOS: JEAN-BERNARD CARON

Taxonomy:

Kingdom: Abundant
Phylum: Abundant
Class: Trilobita (Order: Agnostida)
Species name: Pagetia bootes
Remarks:

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

Described by: Walcott
Description date: 1916
Etymology:

Pagetia – unspecified, likely from Paget Peak (2565 m) in Yoho National Park, named for the Very Reverend Dean Paget, founding member of the Alpine Club of Canada, who, in 1904, made the first recorded ascent.

bootes – unspecified, probably from the Greek Boötes meaning herdsman or ploughman; name of a northern constellation.

Type Specimens: Syntypes (P. bootes ) – USNM62855-62861; Holotype (P. walcotti) – USNM146310 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: P. walcotti Rasetti, 1966.

Other deposits: many species worldwide, in Lower and Middle Cambrian rocks.

Age & Localities:

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

The Walcott and Raymond Quarries on Fossil Ridge. The Trilobite Beds on Mount Stephen.

History of Research:

Brief history of research:

Walcott (1916) published only a very brief description when he first named and illustrated this species. A full account finally appeared in Rasetti (1966), along with that of a new Burgess Shale species, P. walcotti.

Description:

Morphology:

Hard parts: adult dorsal exoskeletons reach about 10 mm in length (including the pygidial spine). The cephalon is semicircular, with a narrow flattened rim crossed by radiating furrows around the front margin. The glabella is narrow and anteriorly pointed with weak lateral constrictions; a delicate spine (usually broken off and not seen) extends up and back from the occipital ring. Tiny eyes are located well out on short, narrow cheeks bounded by proparian facial sutures. There are two thoracic segments. The pygidium is about the same size and outline shape as the cephalon, with a narrow axis of five rings and a terminal piece bearing a slender rearward projecting spine (often broken off). Faint pleural furrows may be visible on the pygidium.

P. walcotti is very similar, but the dorsal exoskeleton bears fine granules.

Unmineralized anatomy: not known.

Abundance:

P. bootes is very common in the Walcott Quarry. It is the third most common trilobite with at least 1000 specimens observed (Caron and Jackson, 2008), prompting Rasetti (1951) to define the “Pagetia bootes faunule” as the conventional shelly fossil assemblage associated with the exceptionally preserved soft-bodied biota. The co-occurring P. walcotti is very rare.

Maximum Size:
10 mm

Ecology:

Life habits: Abundant
Feeding strategies: Abundant
Ecological Interpretations:

Adult eodiscine trilobites were members of the mobile benthic epifauna, possibly, like their co-occuring agnostine cousins, micrograzers or deposit (particle) feeders, adapted to colder, deeper, offshore waters.

References:

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

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

RASETTI, F. 1966. Revision of the North American species of the Cambrian trilobite genus Pagetia. Journal of Paleontology, 40:502-511.

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. 1916. Cambrian trilobites. Smithsonian Miscellaneous Collections, 64(5):301-456.

Other Links:

http://www.trilobites.info/ordagnostida.htm

2D reconstruction – see: http://www.trilobites.info/galagnostida.htm

Ottoia prolifica

3D animation of Ottoia prolifica.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Abundant
Phylum: Abundant
Class: 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:

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:

Life habits: Abundant
Feeding strategies: Abundant
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

Burgessia bella

3D animation of Burgessia bella.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: Abundant
Phylum: Abundant
Class: Unranked clade (stem group arthropods)
Species name: Burgessia bella
Remarks:

Although common, Burgessia has not been re-examined since the 1970s, and its phylogenetic placement is uncertain. It has been described as a basal member of the arachnomorphs, a group that includes chelicerates and trilobites (Briggs and Fortey, 1989; Cotton and Braddy, 2004), but see Edgecombe, 2010.

Described by: Walcott
Description date: 1912
Etymology:

Burgessia – 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.

bella – from the Latin bellus, “beautiful.”

Type Specimens: Lectotype –USNM57676 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:

Described by Walcott in 1912, this species was revised by Simonetta (1970) and restudied in detail by Hughes (1975). Phylogenetic analyses suggest a position within the arachnomorph arthropods (Briggs and Fortey, 1989; Wills et al. 1998; Cotton and Braddy, 2004). The function of the posterior spine was analyzed by comparison with modern horseshoe crabs (Limulus) (Lin, 2009).

Description:

Morphology:

Burgessia is a small, soft-bodied arthropod capped by a dorsal semicircular carapace and possessing a long terminal spine. The carapace is very thin, appearing gently convex in lateral view, and ranging from 4 to 17 mm in length. The length of the spine is approximately 1.4 times the length of the carapace. There is no evidence of compound eyes. The body bears a pair of flexible antennae at the front and ten pairs of appendages which are segmented and branch into two (biramous), three in the head section and seven in the trunk. The inner branch is a walking leg in all ten pairs, and the outer branch is a flagellum in the three head appendages and a gill branch in the seven trunk appendages. A pair of short appendages that are segmented and non-branching (uniramous) is present on the eighth segment of the trunk. The walking branch of the head and trunk appendages terminate with two or three short claws. The telson (last division) has a single unsegmented posterior spine which is often preserved straight, but is bent in some cases. The digestive system is represented by a pair of conspicuous kidney-shaped gut extensions positioned laterally and connected to a central alimentary canal via primary ducts. The mouth would have been positioned ventrally behind a pair of frontal gut lobes, and the anus was located at the end of the central canal near the base of the telson.

Abundance:

Burgessia is known from at least three thousand specimens from the Walcott Quarry and represents about 2.5% of the community (Caron and Jackson, 2008).

Maximum Size:
17 mm

Ecology:

Life habits: Abundant
Feeding strategies: Abundant
Ecological Interpretations:

This animal walked along the surface of the mud with its ten pairs of walking legs, and probably used its antennae and cephalic legs to sweep small food particles through the soft sediment to its ventral mouth. The presence of mud in the stomach has been interpreted as evidence for a deposit mode of feeding, but this could be an artifact of preservation. Swimming abilities would have been minimal. The outer gill branches on the trunk appendages are small and would probably have provided an insufficient surface area to support the gas exchange required for prolonged swimming activities. The stiffened posterior spine could have been used to deter predators or escape burial.

References:

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

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

HUGHES, C. P. 1975. Redescription of Burgessia bella from the Middle Cambrian Burgess Shale, British Columbia. Fossils and Strata, 4: 415-435.

LIN, J.-P. 2009. Function and hydrostatics in the telson of the Burgess Shale arthropod Burgessia. Biology Letters, 5: 376-379.

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

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

Other Links:

None

Takakkawia lineata

Reconstruction of Takakkawia lineata.

© MARIANNE COLLINS

Taxonomy:

Kingdom: Abundant
Phylum: Abundant
Class: Demospongea (Order: Monaxonida)
Species name: Takakkawia lineata
Remarks:

Takakkawia 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:

Takakkawia – from Takakkaw Falls, a waterfall in Yoho National Park, British Columbia, the second tallest in Canada. From the Stoney First Nation Nakoda word “Takakkaw,” for “magnificent,” a descriptive name for the waterfall given by Cornelius Van Horne in 1897.

lineata – from the Latin lineatus, “marked with lines,” this refers to the distinctive blade-like elements along the length of this sponge.

Type Specimens: Lectotype –USNM66539, 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, the Tulip Beds (S7) on Mount Stephen and other smaller sites on Mount Field.

History of Research:

Brief history of research:

Walcott described Takakkawia in his 1920 paper on the Burgess Shale sponges. The genus was redescribed by Rigby in 1986 and again by Rigby and Collins (2004) based on new material collected by the Royal Ontario Museum.

Description:

Morphology:

This is an elongate conical sponge with eight stiff bladelike fins that project radially from the wall of the sponge and extends from a sharp root tip. These fins are composed of fine vertical spicules. Internally the fins are connected to long twisted strands of spicules that form ribbon-like structures. These structures are connected by horizontal ladder-like bundles of spicules. Most spicules are monaxial (simple and elongate) but some could have had three spines. The eight blade-like fins form sharp tips and fan outwards at the oscular margin (the hole at the top). This sponge would have had a large central cavity (spongocoel).

Abundance:

Takakkawia is rare in most sites but abundant in the Walcott Quarry and represents 2.61 % of the community (Caron and Jackson, 2008).

Maximum Size:
40 mm

Ecology:

Life habits: Abundant
Feeding strategies: Abundant
Ecological Interpretations:

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

References:

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

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

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

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

Other Links:

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