The Burgess Shale

Kingdoms: Animalia

Thelxiope palaeothalassia

Thelxiope palaeothalassia (GSC 74990). Articulated specimen (close up to the right), associated with several individuals of the arthropod Canadaspis perfecta. Specimen length = 29 mm. Specimen dry – polarized light. Walcott Quarry.

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

Taxonomy:

Kingdom: Animalia
Phylum: Animalia
Higher Taxonomic assignment: Unranked clade (stem group arthropods)
Species name: Thelxiope palaeothalassia
Remarks:

The affinity of Thelxiope has not been considered in detail because the appendages are unknown.

Described by: Simonetta and Delle Cave
Description date: 1975
Etymology:

Thelxiope – from the Greek thelx meaning “enchanting,” and ops, meaning “voice,” referring to the muse-like appearance of the animal.

palaeothalassia – from the Greek palaios, meaning “ancient,” and thalassios, meaning “marine,” in reference to the age and environment where the animal lived.

Type Specimens: Holotype –USNM144914 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

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

The Walcott Quarry on Fossil Ridge.

History of Research:

Brief history of research:

Walcott (1912) figured two fragmentary specimens as Mollisonia? rara; these were first reinterpreted by Simonetta (1964) within a new genus Parahabelia rara, along with three additional specimens that he thought were related. However, Simonetta and Delle Cave (1975) considered that among those five specimens, the two originally figured by Walcott as M? rara had to be synonymized with M. symmetrica and the other three had to be placed within a new genus and species called Thelxiope palaeothalassia, a name in use since then.

Description:

Morphology:

This species has a relatively wide cephalon and seven segments and resembles Habelia in overall shape. However, in T. palaeothalassia, each segment bears a single prominent spine pointing dorsally. The last segment is armed with a very long pointed telson.

Abundance:

Thelxiope is extremely rare, with only four known specimens.

Maximum Size:
43 mm

Ecology:

Life habits: Animalia
Feeding strategies: Animalia
Ecological Interpretations:

Thelxiope is too poorly known to allow detailed studies of its ecology.

References:

SIMONETTA, A. M. 1964. Osservazioni sugli arthropodi non trilobiti della “Burgess Shale” (Cambriano medio). Monitore Zoologico Italiano, 72 (3-4: III Contributo: I Generi Molaria, Habelia, Emeraldella, Parahabelia (Nov.) Emeraldoides (Nov.): 215-231.

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.

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

Other Links:

None

Thaumaptilon walcotti

Thaumaptilon walcotti (USNM 468028) – Holotype, part and counterpart. Complete specimen. Specimen height = 212 mm. Specimen dry – direct light (far left and far right), wet – polarized light (middle images). Walcott Quarry.

© SMITHSONIAN INSTITUTION – NATIONAL MUSEUM OF NATURAL HISTORY. PHOTOS: JEAN-BERNARD CARON

Taxonomy:

Kingdom: Animalia
Phylum: Animalia
Higher Taxonomic assignment: Unranked clade (stem group cnidarians)
Species name: Thaumaptilon walcotti
Remarks:

Thaumaptilon was first interpreted as a Cambrian member of the frondose Ediacaran Biota, related to cnidarians and particularly to a group of modern anthozoans called pennatulaceans or sea pens (Conway Morris, 1993). This connection is no longer widely accepted (Antcliffe and Brasier, 2008); Thaumaptilon has also been proposed as a critical link between Ediacaran fronds and ctenophores (Dzik, 2002). A position in the cnidarian stem group (i.e. more primitive than the anthozoans) has been supported by the discovery of similar fossils in the Chengjiang Biota (Shu et al., 2006).

Described by: Conway Morris
Description date: 1993
Etymology:

Thaumaptilon – from the Greek thauma, “wonderful,” and ptilon, “soft feather,” after its feather-like appearance.

walcotti – after Charles Walcott, discoverer of the Burgess Shale.

Type Specimens: Holotype –USNM468028 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

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

The Walcott Quarry on Fossil Ridge.

History of Research:

Brief history of research:

Walcott had studied and photographed Thaumaptilon, but never published his work. The fossil specimens were formally described in 1993 by Conway Morris, who had also alluded to them in previous work (1979; 1989; 1990).

Description:

Morphology:

Thaumaptilon is an oblong frond that somewhat resembles a feather; it is bilaterally symmetrical, with a central axis supporting a number of lateral branches. The branches appear to be connected to one another by narrow canals. A blunt holdfast attached the animal to the sea floor. Of the three known specimens, the largest is 21 cm tall and reaches 5 cm across; the smaller specimens – presumed to be juveniles – are only a few centimetres long. The frond is flattened, and tapers slightly towards its tip. It consists of about three dozen branches angled at 45º to the central axis, and primarily grew by inflation – perhaps with some addition of branches by apical budding. Unlike modern sea pens, Thaumaptilon’s branches attach to a common base. Lines of pustules on one side of the frond have been interpreted as retracted zooids (individual members of a colonial organism), which are arranged very haphazardly in comparison to the neat combs seen in modern sea pens.

Abundance:

Only three specimens are known.

Maximum Size:
210 mm

Ecology:

Life habits: Animalia
Feeding strategies: Animalia
Ecological Interpretations:

The holdfast would have anchored the organism to the soft sediment of the sea floor, and could perhaps contract to adjust the height and angle of the frond. Based on the interpretation of the pustules as zooids, a colonial, suspension-feeding lifestyle has been proposed. It has been suggested that Thaumaptilon could retract into its stem when threatened, for protection (Conway Morris, 1998).

References:

ANTCLIFFE, J. B. AND M. D. BRASIER. 2008. Charnia at 50: Developmental models for Ediacaran fronds. Palaeontology, 51(1): 11-26.

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

CONWAY MORRIS, S. 1989. Burgess Shale faunas and the Cambrian explosion. Science, 246(4928): 339.

CONWAY MORRIS, S. 1990. Late Precambrian and Cambrian soft-bodied faunas. Annual Review of Earth and Planetary Sciences, 18(1): 101-122.

CONWAY MORRIS, S. 1993. Ediacaran-like fossils in Cambrian Burgess Shale-type faunas of North America. Palaeontology, 36(3): 593-635.

CONWAY MORRIS, S. 1998. The Crucible of Creation, the Burgess Shale and the Rise of Animals. Oxford University Press, 242 p.

SHU, D. G., S. CONWAY MORRIS, J. HAN, Y. LI, X. L. ZHANG, H. HUA, Z. F. ZHANG, J. N. LIU, J. F. GUO, Y. YAO AND K. YASUI. 2006. Lower Cambrian vendobionts from China and early diploblast evolution. Science, 312(5774): 731-734.

Other Links:

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

Tegopelte gigas

Tegopelte gigas (USNM 189201) – Holotype. Complete specimen showing antennae and appendages partially prepared near the back. Specimen length = 270 mm. Specimen dry – direct (top) and polarized light (bottom). Walcott Quarry.

© SMITHSONIAN INSTITUTION – NATIONAL MUSEUM OF NATURAL HISTORY. PHOTOS: JEAN-BERNARD CARON

Taxonomy:

Kingdom: Animalia
Phylum: Animalia
Higher Taxonomic assignment: Unranked clade (stem group arthropods)
Species name: Tegopelte gigas
Remarks:

Tegopelte is usually compared to the soft-bodied “trilobites” such as Naraoia and Saperion, but the exact relationships of these taxa to the mineralized trilobites is uncertain (Whittington, 1977). The tegopeltids and other trilobite-like arthropods are sometimes referred to as Trilobitoidea, which when grouped together with the trilobites form the Lamellipedians (Hou and Bergström, 1997; Wills et al., 1998; Edgecombe and Ramsköld, 1999). This group has been variously placed in the upper stem lineage of the arthropods (Budd, 2002), or in the stem lineage of either the mandibulates (Scholtz and Edgecombe, 2006) or the chelicerates (Cotton and Braddy, 2004).

Described by: Simonetta and Delle Cave
Description date: 1975
Etymology:

Tegopelte – from the Greek tegos, “tile,” and pelte, “leather-shield,” referring to the shape of the dorsal body covering.

gigas – from the Greek gigas, “giant,” referring to the large size of the animal.

Type Specimens: Holotype –USNM189201 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

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

The Walcott Quarry on Fossil Ridge.

History of Research:

Brief history of research:

Tegopelte was first described by Simonetta and Delle Cave (1975) to include only two relatively large specimens. This original description showed Tegopelte to have a cephalon with six or seven pairs of walking appendages, a thorax of four tergites each bearing five appendages, and a tail segment with ten appendages. Whittington (1985) re-examined the animal, reducing the number of head appendages to three, and describing the thorax as having only three tergites with three appendages each. The tail in Whittington’s (1985) reconstruction had two segments with a total of 20 appendages. Later re-examination by Ramsköld et al. (1996) suggested that the body has no tergites, but instead consists of an undivided dorsal shield. Tegopelte has been grouped together with the Chengjiang taxon Saperion to form the Tegopeltidae (Ramsköld et al., 1996; Hou and Bergström, 1997), a clade later confirmed by cladistic analysis (Edgecombe and Ramsköld, 1999; Hendricks and Lieberman, 2008).

Description:

Morphology:

The dorsal morphology of Tegopelte consists of an elongated oval-shaped dorsal shield that is featureless and undivided. The length of the two known specimens is 25.7 cm and 27.0 cm, making it one of the largest arthropods in the Burgess Shale. The ventral morphology consists of a pair of multi-segmented antennae at the front of the body, followed by a series of identical limbs that are segmented and branch into two (biramous), totaling approximately 33 along the entire body. The biramous limbs have a walking branch made up of six segments with a pair of spines on the terminal segment, and a filamentous branch where numerous elongated oval blades attach to a central shaft. The biramous limbs decrease in size towards the posterior end of the body.

Abundance:

Tegopelte is extremely rare, with only two known specimens.

Maximum Size:
270 mm

Ecology:

Life habits: Animalia
Feeding strategies: Animalia
Ecological Interpretations:

Tegopelte probably spent much of its time walking on the seafloor, based on the presence of many appendages. It used the segmented branches of its biramous appendages for walking, and it is likely that the filamentous branches were used for oxygen exchange, and to propel the animal through the water during short bursts of swimming. The antennae would have been used to sense the environment. The lack of eyes, gut glands and feeding appendages make it difficult to allocate a feeding strategy to Tegopelte.

References:

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

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.

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.

EDGECOMBE, G. D. and L. RAMSKÖLD. 1999. Relationships of Cambrian Arachnata and the systematic position of Trilobita. Jounral of Paleontology, 73: 263-287.

HENDRICKS, J. R. AND B. S. LIEBERMAN. 2008. New phylogenetic insights into the Cambrian radiation of arachnomorph arthropods. Journal of Paleontology, 83: 585-594.

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

RAMSKÖLD, L., J. CHEN, G. D. EDGECOMBE AND G. ZHOU. 1996. Preservational folds simulating tergite junctions in tegopeltid and naraoiid arthropods. Lethaia, 29: 15-20.

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.

WHITTINGTON, H. B. 1977. The Middle Cambrian trilobite Naraoia, Burgess Shale, British Columbia. Philosophical Transactions of the Royal Society of London, B, 280: 409-443.

WHITTINGTON, H. B. 1985. Tegopelte gigas, a second soft-bodied trilobite from the Burgess Shale, Middle Cambrian, British Columbia. Journal of Paleontology, 59: 1251-1274.

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

Stephenospongia magnipora

Stephenospongia magnipora (ROM 43127) – Holotype. Fragment of the only known specimen of the species showing large holes in the wall of this sponge. Specimen height = 44 mm. Specimen dry – polarized light. Trilobite Beds on Mount Stephen.

© ROYAL ONTARIO MUSEUM. PHOTO: JEAN-BERNARD CARON

Taxonomy:

Kingdom: Animalia
Phylum: Animalia
Higher Taxonomic assignment: Hexactinellida (Order: Reticulosa)
Species name: Stephenospongia magnipora
Remarks:

Stephenospongia is placed in the Family Hintzespongiidae (primitive hexactinellids). Hexactinellid sponges (glass sponges) have a skeleton composed of four to six-pointed spicules. They are considered to be an early branch within the Porifera phylum due to their distinctive composition.

Described by: Rigby
Description date: 1986
Etymology:

Stephenospongia – from Mount Stephen (3,199 m), a mountain peak in Yoho National Park, named after George Stephen (1829 – 1921), first president of the Canadian Pacific Railway and the Latin spongia, meaning “sponge.”

magnipora – from the Latin magnus, “great,” and porus, “pore.” The name makes reference to the large pores present in the skeleton of this sponge.

Type Specimens: Holotype –ROM43127 in the Royal Ontario Museum, Toronto, Canada.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

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

The Trilobite Beds on Mount Stephen.

History of Research:

Brief history of research:

Stephenospongia was described by Rigby (1986) (see also Rigby and Collins 2004) based on a single specimen discovered by the Royal Ontario Museum in 1982.

Description:

Morphology:

Stephenospongia has a conical and almost cylindrical shape. The skeleton is composed of six rayed spicules (called hexactines) typical of the hexactinellid sponges. The spicules mesh together to form a single layer and are arranged in an irregular fashion especially around holes in the sponge wall. Prominent holes organized in vertical and horizontal rows are separated by tracts of spicules with ray lengths reaching more than one centimetre. The basal and top parts are not preserved.

Abundance:

Only a single specimen is known and comes from the Trilobite Beds.

Maximum Size:
44 mm

Ecology:

Life habits: Animalia
Feeding strategies: Animalia
Ecological Interpretations:

Stephenospongia 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:

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.

Other Links:

None

Stephenoscolex argutus

Stephenoscolex argutus (USNM 83936b) – Holotype. Specimen showing the head (top left) followed by the trunk, which is lined by narrow parapodia and setae. Filamentous structures around the body probably represent cyanobacteria. Specimen length = 32 mm. Specimen dry – direct light (left) and wet – direct light (right). Walcott Quarry.

© SMITHSONIAN INSTITUTION – NATIONAL MUSEUM OF NATURAL HISTORY. PHOTOS: JEAN-BERNARD CARON

Taxonomy:

Kingdom: Animalia
Phylum: Animalia
Higher Taxonomic assignment: Unranked clade (stem group polychaetes)
Species name: Stephenoscolex argutus
Remarks:

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

Described by: Conway Morris
Description date: 1979
Etymology:

Stephenoscolex – from the Greek scolex, “worm,” and Mount Stephen. Mount Stephen (3,199 m) was named after George Stephen (1829 – 1921), first president of the Canadian Pacific Railway.

argutus – from the Latin argutus, “bright,” in recognition of the shininess of the fossils.

Type Specimens: USNM – 83936b in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA. Paratype –ROM32574 in the Royal Ontario Museum, Toronto, ON, Canada.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

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

The Walcott Quarry on Fossil Ridge.

History of Research:

Brief history of research:

Walcott (1911; 1931) included the holotype of this species within Canadia dubia, which Simon Conway Morris, in his 1979 re-examination of Burgess Shale polychaetes, reclassified as Stephenoscolex. Conway Morris found a further partial specimen in the ROMcollections, and further specimens have since been recovered by the ROMbelow the Walcott Quarry. However, this additional material awaits detailed study; since the published description rests on two specimens, it must be treated with caution (Eibye-Jacobsen, 2004).

Description:

Morphology:

The worm has a slim body, around 1 mm wide, reaching around 3 cm in length. Its head bears two pairs of appendages extending from its front and sides. It has around forty further segments, each of which bear simple lateral projections (uniramous) called parapodia. The parapodia each bear around fifteen short and simple setae. Cirri and branchiae are absent.

Abundance:

Stephenoscolex was considered one of the rarest annelids from the Burgess Shale but additional material has now been collected from the Walcott Quarry representing 0.28% of the specimens counted in the community (Caron and Jackson, 2008).

Maximum Size:
32 mm

Ecology:

Life habits: Animalia
Feeding strategies: Animalia
Ecological Interpretations:

There is little that can confidently be stated about the life habit of this animal, but the pattern of spines suggests that it crept or swum over or in the sediment.

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.

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

Other Links:

None

Stanleycaris hirpex

Stanleycaris hirpex (ROM 59944) – Holotype, part and counterpart. Individual claw. Specimen length = 29 mm. Specimen dry – polarized light. Stanley Glacier.

© ROYAL ONTARIO MUSEUM. PHOTOS: JEAN-BERNARD CARON

Taxonomy:

Kingdom: Animalia
Phylum: Animalia
Higher Taxonomic assignment: Dinocarida (Order: Radiodonta, stem group arthropods)
Species name: Stanleycaris hirpex
Remarks:

Stanleycaris is an anomalocaridid closely related to Hurdia and Laggania. 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).

Described by: Caron et al.
Description date: 2010
Etymology:

Stanleycaris – from Stanley Glacier, 40 kilometres southeast of the Burgess Shale in Kootenay National Park, where the fossils come from and the Latin caris, meaning “shrimp.” The name Stanley was given after Frederick Arthur Stanley (1841-1908), Canada’s sixth Governor General.

hirpex – from the Latin, hirpex, meaning “large rake,” in reference to the rake-like aspect of the appendage.

Type Specimens: Holotype –ROM59944 in the Royal Ontario Museum, Toronto, Canada.
Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

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

The Stanley Glacier in Kootenay National Park.

History of Research:

Brief history of research:

The first fossils of this species were collected by the Royal Ontario Museum in 1996 from talus slopes, but it was not until 2008, during a larger expedition, that specimens were discovered in their proper stratigraphic context. A description of this new genus and species soon followed (Caron et al., 2010).

Description:

Morphology:

Stanleycaris is known from paired or isolated grasping appendages and disarticulated assemblages. The entire animal might have reached 15 centimetres in total length. The grasping appendages range in length from 1.2 cm to 3 cm and have eleven segments (or podomeres), with five spinous ventral blades on the second to sixth segments. Double-pointed dorsal spines are particularly prominent from the second to the sixth segment, decreasing in size towards the distal end of the appendage. The longest of these robust spines is typically two to three times shorter than the ventral blades. The last segment has three curved terminal spines. Mouthparts are represented by circlets of plates bearing teeth around a central square opening. Assemblages are poorly preserved, and the best example consists of a pair of grasping appendages, a mouth part, and remnants of what might represent parts of a carapace or gill structures.

Abundance:

This species is relatively rare and only found near Stanley Glacier.

Maximum Size:
150 mm

Ecology:

Life habits: Animalia
Feeding strategies: Animalia
Ecological Interpretations:

Stanleycaris is considered a predator or a scavenger, based on the morphology of its frontal appendages and mouth parts. The comb-like ventral blades might have been useful for searching small prey items or disturbing carcasses at the water-sediment interface and within the flocculent level of the mud.

References:

CARON, J.-B., R. GAINES, G. MANGANO, M. STRENG AND A. DALEY. 2010. A new Burgess Shale-type assemblage from the “thin” Stephen Formation of the Southern Canadian Rockies. Geology, 38(9): 811-814.

CHEN, J. Y., L. RAMSKÖLD AND G. Q. ZHOU. 1994. Evidence for monophyly and arthropod affinity of Cambrian giant predators. Science, 264: 1304-1308.

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.

HOU, X., J. BERGSTRÖM AND P. AHLBERG. 1995. Anomalocaris and other large animals in the Lower Cambrian Chengjiang fauna of Southwest China. GFF, 117: 163-183.

Other Links:

http://geology.geoscienceworld.org/cgi/content/full/38/9/811?ijkey=ZQFY537sTggAw&keytype=ref&siteid=gsgeology

Sphenothallus sp.

Taxonomy:

Sphenothallus sp. (GSC 134789). Fragment of a large specimen showing longitudinal thickenings clearly differentiated near the aperture area (to the right). A Micromitra (Dictyonina) brachiopod is attached to the lower part of the tube. Approximate specimen length = 50 mm. Specimen dry – direct light. Trilobite Beds on Mount Stephen.

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

Kingdom: Animalia
Phylum: Animalia
Higher Taxonomic assignment: Unranked clade (stem group cnidarians)
Species name: Sphenothallus sp.
Remarks:

Sphenothallus has been compared to some form of tubiculous annelid worm or the sessile polyp stage of a scyphozoan jellyfish that builds tapered, chitinous tubes fixed to the substrate by an attachment disc (Van Iten et al., 2002).

Described by: Van Iten et al.
Description date: 2002
Etymology:

Sphenothallus – from the Greek sphen, “wedge”, and thallos, “branch.”

Species name not determined.

Type Specimens: Not applicable
Other species:

Burgess Shale and vicinity: Many shared similarities suggest that other thecate Burgess Shale fossils such as Byronia annulata, Cambrorhytium major, C. fragilis and Tubulella flagellum, may be related to Sphenothallus sp.

Other deposits: Other species occur worldwide in rocks from the Cambrian to the Silurian periods. Sphenothallus is also known in the Kaili Formation (Zhu et al., 2000).

Age & Localities:

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

The Trilobite Beds on Mount Stephen.

History of Research:

Brief history of research:

Two specimens from the Trilobite Beds were illustrated in 2002 (Van Iten et al.). A third previously unrecognized specimen was identified in the Geological Survey of Canada collections in Ottawa (Billings collection) in the Spring of 2010. Owing to the relatively low degree of morphological variations among all known species, it is not currently possible to assign the Burgess Shale form to any particular species without better preserved specimens.

Description:

Morphology:

The chitinophosphatic tube (theca) of Sphenothallus consists of longitudinal thickenings which are particularly obvious towards the aperture area. The tube is gently curved and does not seem to branch. The maximum diameter of the largest specimen is about 4 mm for a length of about 75 mm. A thin wall is present between the longitudinal thickenings and terminates in a smooth margin near the aperture, a couple of millimeters beyond the longitudinal thickenings. The tube is roughly circular in the apical region and is very slender, with the two longitudinal thickenings less differentiated in this area. The surface of the entire tube including thickenings is smooth with no evidence of ridges or annulations. All three specimens lack the apical ends, so it is not evident that this species had a holdfast and there is no evidence of soft-tissue preservation.

Abundance:

Only three specimens known from the Trilobite Beds on Mount Stephen.

Maximum Size:
75 mm

Ecology:

Life habits: Animalia
Feeding strategies: Animalia
Ecological Interpretations:

The theca of Sphenothallus was likely attached to the substrate via an apical disc as can be seen in other better known species. The absence of soft tissue preservation makes the assignment to a particular feeding strategy tentative. By comparison with possible related forms such as Cambrorhytium, a carnivorous or suspension feeding habit seems possible.

References:

VAN ITEN, H., M.-Y. ZHU AND D. COLLINS. 2002. First report of Sphenothallus Hall, 1847 in the Middle Cambrian. Journal of Paleontology, 76: 902-905.

ZHU, M.-Y., H. VAN ITEN, R. S. COX, Y.-L. ZHAO AND B.-D. ERDTMANN. 2000. Occurrence of Byronia Matthew and Sphenothallus Hall in the Lower Cambrian of China. Paläontologische Zeitschrift, 74: 227-238.

Other Links:

None

Skania fragilis

Skania fragilis (ROM 60752) – Part and counterpart (first and second rows). Complete specimen showing antennae. Specimen length = 11 mm. Specimen dry – polarized light (left column) and wet (right column). Raymond Quarry.

© ROYAL ONTARIO MUSEUM. PHOTOS: JEAN-BERNARD CARON

Taxonomy:

Kingdom: Animalia
Phylum: Animalia
Higher Taxonomic assignment: Unranked clade (stem group arthropods)
Species name: Skania fragilis
Remarks:

The affinity of Skania is controversial, but most agree it is related to the arthropods. It is similar to Primicaris (Lin et al., 2006; Zhang et al., 2007), and both taxa have been compared to soft-bodied trilobites like Naraoia (Walcott, 1931; Zhang et al., 2007; Hou and Bergström, 1997). Other researchers suggest these taxa are related to the enigmatic Ediacaran taxon Parvancorina (Delle Cave and Simonetta, 1975; Gehling, 1991; Conway Morris, 1993; Simonetta and Insom, 1993), with all three taxa forming a clade in sister group position relative to the trilobites (Lin et al., 2006).

Described by: Walcott
Description date: 1931
Etymology:

Skania – from Skana, the name of a glacier near Mount Robson, British Columbia, Canada.

fragilis – from the Latin fragilis, “brittle,” referring to the delicate nature and small size of the animal.

Type Specimens: Holotype –USNM83950 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: Skania sundbergi Lin et al. 2006 from the Kaili Formation, China.

Age & Localities:

Age:
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:

Skania fragilis was first described by Walcott (1931) in a posthumous monograph published by his assistant Charles Resser. Resser compared Skania to the trilobites and Naraoia. However in a redescription by Delle Cave and Simonetta (1975), it was suggested instead that Skania was closely related to the Ediacaran taxon Parvancorina minchami Glaessner 1958. This affinity has been much discussed (Gehling, 1991; Conway Morris, 1993; Simonetta and Insom, 1993; Lin et al. 2006), and Skania has also been compared extensively with Primicaris Zhang et al. 2003. Skania and Primicaris have also been interpreted as juveniles (protaspides) of naraoiids (Hou and Bergström, 1997).

Description:

Morphology:

Skania has a single, undifferentiated, soft dorsal shield that is roughly kite-shaped. The dorsal shield is rounded at the front of the head, and tapers towards the posterior of the body, ending in a pair of short margin spines at the posterior end. At the point of maximum width there are sharp genal spines directed posteriorly. The posterior margin of the head is delineated by a narrow rim that is strongly arched forward, with the cephalic region occupying one-quarter of the exoskeletal length. A midgut is preserved in the axial region of the body trunk. Appendages are poorly preserved but consist of a pair of anterior antennae and ten or more paired body limbs.

Abundance:

Skania fragilis is known from fewer than 40 specimens in total.

Maximum Size:
17 mm

Ecology:

Life habits: Animalia
Feeding strategies: Animalia
Ecological Interpretations:

The ecology of Skania is poorly known because the details of its morphology remain enigmatic. The form of the appendages is assumed to be biramous based on the overall similarity with Primicaris, which possesses biramous appendages, meaning that both animals may have walked on the seafloor, using their filamentous appendages for oxygen exchange and occasional swimming. Skania lacks eyes, so it likely used its antennae to sense the environment. The feeding strategy is unknown.

References:

CONWAY MORRIS, S. 1993. Ediacaran-like fossil in Cambrian Burgess Shale-type faunas of North America. Palaeontology, 36: 593-635.

DELLE CAVE, L. AND A. M. SIMONETTA. 1975. Notes on the morphology and taxonomic position of Aysheaia (Onycophora?) and of Skania (undetermined phylum). Monitore Zoologico Italiano New Series, 9: 67-81.

GEHLING, J. G. 1991. The case for Ediacaran fossil roots to the metazoan tree, p. 181-223. In B. P. Radhakrishna (ed.), The world of Martin F. Glaessner. Geological Society of India, Bangalore.

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

LIN, J., S. M. GON III, J. G. GEHLING, L. E. BABCOCK, Y. ZHAO, X. ZHANG, S. HU, J. YUAN M. YU AND J. PENG. 2006. A Parvancorina-like arthropod from the Cambrian of South China. Historical Biology, 18: 33-45.

SIMONETTA, A. M. AND E. INSOM. 1993. New animals from the Burgess Shale (Middle Cambrian) and their possible significance for the understanding of the Bilateria. Bolletino di Zoologia, 60: 97-107.

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

ZHANG, X., D. SHU AND D. H. ERWIN. 2007. Cambrian naraoiids (Arthropoda): morphology, ontogeny, systematics, and evolutionary relationships. Palaeontological Society Memoir, 68: 1-52.

Other Links:

None

Sidneyia inexpectans

3D animation of Sidneyia inexpectans.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

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

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

Described by: Walcott
Description date: 1911
Etymology:

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

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

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

Burgess Shale and vicinity: none.

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

Age & Localities:

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

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

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

History of Research:

Brief history of research:

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

Description:

Morphology:

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

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

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

Abundance:

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

Maximum Size:
160 mm

Ecology:

Life habits: Animalia
Feeding strategies: Animalia
Ecological Interpretations:

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

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

References:

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

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

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

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

BUDD, G. E. AND M. J. TELFORD. 2009. The origin and evolution of arthropods. Nature, 457(7231): 812-817.

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., R. GAINES, G. MANGANO, M. STRENG, AND A. DALEY. 2010. A new Burgess Shale-type assemblage from the “thin” Stephen Formation of the Southern Canadian Rockies. Geology, 38: 811-814.

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. Jounral 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.

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

SIMONETTA, A. M. 1963. Osservazioni sugli artropodi non trilobiti della Burgess Shale (Cambriano medio). II. Contributo: I Generai Sidneyia ed Amiella Walcott 1911. Monitore Zoologico Italiano, 70: 97-108.

STØMER, L. 1944. On the relationships and phylogeny of fossil and recent Arachnomorpha. Norsk Videnskaps-Akademi Skrifter I. Matematisk-Naturvidenskaplig Klasse, 5: 1-158.

WALCOTT, C. D. 1911. Middle Cambrian Merostomata. Cambrian geology and paleontology II. Smithsonian Miscellaneous Collections, 57: 17-40.

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

WHITTINGTON, H. B. 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.

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, pp. 33-105. In G. D. Edgecombe (ed.), Arthropod fossils and phylogeny. Columbia University Press, New York.

ZHU, X., H. JIAN AND S. DEGAN. 2002. New occurrence of the Burgess Shale arthropod Sidneyia in the Early Cambrian Chengjiang Lagerstätte (South China), and revision of the arthropod Urokodia. Alcheringa: An Australasian Journal of Palaeontology, 26: 1-18.

Other Links:

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

Selkirkia columbia

3D animation of Selkirkia columbia.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Kingdom: Animalia
Phylum: Animalia
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: Animalia
Feeding strategies: Animalia
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