The Burgess Shale

Walcottidiscus typicalis

Walcottidiscus typicalis (GSC 45368). Complete but poorly preserved specimen. Specimen diameter = 18 mm. Specimen dry – direct light. Walcott Quarry.

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

Taxonomy:

Class: Edrioasteroidea (Order: Edrioasteroida, stem group echinoderms)
Remarks:

Walcottidiscus is a poorly known edrioasteroid, an extinct group of echinoderms (Smith, 1985).

Species name: Walcottidiscus typicalis
Described by: Bassler
Description date: 1935
Etymology:

Walcottidiscus – from Charles Walcott, the discoverer of the Burgess Shale, and the Greek diskos, “disc.” The name refers to the flattened appearance of the fossils.

typicalis – from the Greek typikos, “type,” perhaps in reference to the single specimen originally described.

Type Specimens: Holotype –USNM90754 (W. typicalis),USNM90755 (W. magister) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: W. magister Bassler, 1935 from the Walcott Quarry on Fossil Ridge (but see below paragraph brief history of research).

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:

Two species known from a single specimen each were originally described by Bassler in 1935 and 1936: a small form W. typicalis, and a larger form W. magister respectively. However, W. magister is now thought to belong to W. typicalis (Smith, 1985) but additional fossil material would be required to confirm this hypothesis. Walcottidiscus resembles Kailidiscus chinensis, a chinese form from the Middle Cambrian Kaili deposit, but remains too poorly known to draw more detailed comparisons between the two genera (Zhao et al., 2010).

Description:

Morphology:

The body (theca) is ovoid in outline and has a relatively small dorsal surface compared to the ventral one. The upper central part of the theca is not calcified, but the outer zone is composed of small calcified plates. A five star-shaped food groove lined with small plates (the ambulacra) is present on the upper surface. The five arms of the ambulacra are arranged in a 2:1:2 fashion around the mouth, and they are at first straight and then turn to the left near the edge of the theca. Differences between the two species are the size and degree of ambulacral curvature, but those differences could simply be a factor of growth.

Abundance:

Walcottidiscus is very rare only two specimens were originally described. A few additional specimens are known in the Burgess Shale collections of the Geological Survey of Canada and the Royal Ontario Museum.

Maximum Size:
64 mm

Ecology:

Ecological Interpretations:

Walcottidiscus was most likely resting on the seafloor. Food particles were transported by food grooves (ambulacrum) into a central mouth at the top of the theca.

References:

BASSLER, R. S. 1935. The classification of the Edrioasteroidea. Smithsonian Miscellaneous Collections, 93: 1-11.

BASSLER, R. S. 1936. New species of American Edrioasteroidea. Smithsonian Miscellaneous Collections, 95: 1-33.

SMITH, A. B. 1985. Cambrian eleutherozoan echinoderms and the early diversification of edrioasteroids. Palaeontology, 28: 715-756.

ZHAO, Y., C. D. SUMRALL, R. L. PARSLEY AND J. I. N. PENG. 2010. Kailidiscus, a new plesiomorphic edrioasteroid from the basal Middle Cambrian Kaili biota of Guizhou province, China. Journal of Paleontology, 84: 668-680.

Other Links:

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Gogia stephenensis

Gogia stephenensis (GSC 25954) – Paratype. Small specimen showing strongly ridged plates and three brachioles near the top. Specimen height = 16 mm. Specimen dry – direct light (left), dry – polarized light (right). Walcott Quarry.

© Geological Survey of Canada. Photos: Jean-Bernard Caron

Taxonomy:

Class: Eocrinoidea (Order: Gogiida, stem group echinoderms)
Remarks:

Gogia is a common eocrinoid, related to the blastozoans, an early group of echinoderms (Sprinkle, 1973).

Species name: Gogia stephenensis
Described by: Sprinkle and Collins
Description date: 2006
Etymology:

Gogia – from Gog Lake, 60 km southeast of Field in Mount Assiniboine Provincial Park.

stephenensis – from Mount Stephen (3,199 m), the mountain peak in Yoho National Park from which the specimens were collected. Named in 1886 for George Stephen, the first president of the Canadian Pacific Railway.

Type Specimens: Holotype –ROM57247 in the Royal Ontario Museum, Toronto, Ontario, Canada.
Other species:

Burgess Shale and vicinity: none.

Other deposits: G. prolifica Walcott 1917 (type species) from the Middle Cambrian Mount Whyte formation of Alberta; G. gondi Ubaghs, 1987 from the upper Middle Cambrian of France; G. granulosa Robinson 1965 from the early Middle Cambrian Spence Shale of Utah and the Early-Middle Cambrian of Mexico; G. gondi Ubaghs, 1987 from the the Middle Cambrian of Montagne Noire, G. hobbsi Sprinkle 1973; G. kitchenerensis Sprinkle 1973 from the Spence Shale of Utah; G. longidactylus (Walcott 1886) Robinson 1965 from the Middle Cambrian of Nevada; G. multibrachiatus (Kirk 1945) Robinson 1965 from the Middle Cambrian Bright Angel Shale, Grand Canyon, Arizona; G. ojenai Durham 1978 from the late Early Cambrian of California; G. palmeri Sprinkle 1973 from the Middle Cambrian of Idaho; G. parsleyi Zamora 2009 from the Middle Cambrian Murero Formation of Spain; and G. spiralis Robinson 1965 from the Middle Cambrian Wheeler Shale of Utah. (See complete list of references in Sprinkle, 1973 and Zamora et al. 2010.)

Age & Localities:

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

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

History of Research:

Brief history of research:

Though the genus Gogia was described by Walcott in 1917 from material collected in the Lower Middle Cambrian Mount Whyte Formation, it was not recognized in the Burgess Shale until 1966 when a single specimen was discovered by the Geological Survey of Canada in the Walcott Quarry. Together with additional specimens identified in the Walcott collection, Sprinkle named this form G.(?) radiata (Sprinkle, 1973). Additional material collected by the Royal Ontario Museum led to designate the current species replacing G.(?) radiata (Sprinkle and Collins, 2006).

Description:

Morphology:

G. stephenensis consists of a rounded conical body (theca) on a short stalk with around a dozen straight arms near the top (brachioles), which in this species may branch at least once along their length. The theca is composed of a patchwork of interlocking plates. The larger plates are strongly ridged.

Abundance:

Though the genus is abundant in other deposits, Gogia is markedly rare in all the Burgess Shale localities.

Maximum Size:
40 mm

Ecology:

Ecological Interpretations:

Gogia was attached to the sea floor by a short calcified stalk and fed by capturing small water-borne particles with its thin, tendril-like arms. Food particles were transported from the arms to food grooves (ambulacrum) into a central mouth at the top of the theca.

References:

SPRINKLE, J. 1973. Morphology and evolution of blastozoan echinoderms. Harvard University, Museum of Comparative Zoology Special Publication: 1-284.

SPRINKLE, J. AND D. COLLINS. 2006. New eocrinoids from the Burgess Shale, southern British Columbia, Canada, and the Spence Shale, northern Utah, USA. Canadian Journal of Earth Sciences, 43: 303-322.

WALCOTT, C. D. 1917. Cambrian geology and paleontology. IV. Fauna of the Mount Whyte Formation: Smithsonian Miscellaneous Collections, 63: 61-114.

ZAMORA, S. R. GOZALO AND E. LINÑÁN. 2009. Middle Cambrian Gogiid Echinoderms from Northeast Spain: Taxonomy, Palaeoecology, and Palaeogeographic Implications. Acta Palaeontologica Polonica, 54: 253-265.

Other Links:

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Echmatocrinus brachiatus

Reconstruction of Echmatocrinus brachiatus.

© Marianne Collins

Taxonomy:

Class: Crinoidea? (stem group echinoderms)
Remarks:

The taxonomic position of Echmatocrinus is uncertain. This animal is either considered as a primitive crinoid (Sprinkle, 1976, Sprinkle and Collins, 1998), a cnidarian (Conway Morris, 1993) or an octocoral (Ausich and Babcock, 1998, 2000).

Species name: Echmatocrinus brachiatus
Described by: Sprinkle
Description date: 1973
Etymology:

Echmatocrinus – from the Greek echmatos, “holdfast, or stalk,” and krinos, “lily.” The name refers to the shape and the attachment part.

brachiatus – from the Greek brachiatus, “having arms,” in reference to the presence of arms.

Type Specimens: Holotype – GSC25962 in the Geological Survey of Canada, Ottawa, 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. A couple of specimens were also collected from the east side of Mount Field.

History of Research:

Brief history of research:

Echmatocrinus was first described by Sprinkle in 1973 as a primitive crinoid based on five specimens, four of which were originally collected by Walcott but never published. The fifth and best preserved specimen, now the holotype, was collected by the Geological Survey of Canada in 1967. Conway Morris reinterpreted Echmatocrinus as a possible cnidarian in 1993 and Ausich and Babcock (1998) suggested an octocoral affinity. Both of these newer interpretations were rejected by Sprinkle and Collins in a larger revision of all material available including new specimens collected by the Royal Ontario Museum (1998, but see Ausich and Babcock 1998).

Description:

Morphology:

The body consists of a small attachment disk (holdfast), a conical stalk ending into a wide cup (theca) with 7 to 10 short arms attached to the edge of it. Soft appendages are present on alternate sides of each arm. The stalk is at least the length of the cup and arms combined. A number of plates, presumably originally weakly mineralized cover the entire body. The plates are irregular in shape and might have sutures along them. Plates are more regular and pronounced in the arms. The arms are uniserial (i.e., they do not branch) and could fold on themselves. A surface texture or ornament is also present on the external parts of the plates. This ornament is interpreted by some authors as evidence of a stereom, the characteristic mineralized skeleton of all echinoderms. The locations of the mouth and anus are uncertain.

Abundance:

Echmatocrinus is very rare in the Walcott Quarry, where it makes up a negligible percentage (0.01%) of the community (Caron and Jackson, 2008). About two dozen specimens are known in total from three different localities.

Maximum Size:
185 mm

Ecology:

Ecological Interpretations:

Echmatocrinus was attached to skeletal debris on the seafloor and evidently it needed hard substrates for growth. It is often found in clusters of several individuals thus showing a gregarious habit. Food particles were likely transported along the arms to a central mouth near the summit of the cup.

References:

AUSICH, W. I. AND L. E. BABCOCK. 1998. The phylogenetic position of Echmatocrinus brachiatus, a probable octocoral from the Burgess shale. Palaeontology, 41: 193-202.

AUSICH, W. I. AND L. E. BABCOCK. 2000. Echmatocrinus, a Burgess Shale animal reconsidered. Lethaia, 33: 92-94.

SPRINKLE, J. 1976. Biostratigraphy and paleoecology of Cambrian echinoderms from the Rocky Mountains, p. 61-73. In R. A. Robison and A. J. Rowell (eds.), Paleontology and depositional environments: Cambrian of Western North America. 23. Brigham Young University Geology Studies.

SPRINKLE, J. AND D. COLLINS. 1998. Revision of Echmatocrinus from the Middle Cambrian Burgess Shale of British Columbia. Lethaia, 31: 269-282.

Other Links:

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Lyracystis radiata

Reconstruction of Lyracistis radiata.

© MARIANNE COLLINS

Taxonomy:

Class: Eocrinoidea (Order: Gogiida, stem group echinoderms)
Remarks:

Lyracystis is an eocrinoid, related to the blastozoans, an early group of echinoderms (Sprinkle, 1973).

Species name: Lyracystis radiata
Described by: Sprinkle
Description date: 1973
Etymology:

Lyracystis – from the Greek lyra, “lyre, flute,” and kystis, “bladder, sac,” in reference to the globular theca bearing lyre-shaped arms.

radiata – from the Latin radiatus, “rayed,” in reference to the position of the arms.

Type Specimens: Holotype –USNM165399 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: L. reesei Sprinkle and Collins, 2006 from the Middle Cambrian Spence Shale in Utah.

Age & Localities:

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

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

History of Research:

Brief history of research:

This species was originally described as Gogia (?) radiata (Sprinkle, 1973), but new fossil material discovered by the Royal Ontario Museum led to a revision of the previously available specimens and the recognition of two different gogiid forms. Some specimens of G.(?) radiata were assigned to a new genus, Lyracystis radiata, and others were assigned to a new species of Gogia, G. stephenensis (Sprinkle and Collins, 2006).

Description:

Morphology:

Lyracystis is the largest eocrinoid from the Burgess Shale reaching up to an estimated 21 cm in height. The stem was longer than the length of the main body (theca) and arms combined. Three large lyre-shaped arms are attached to the edges of the top of the theca, each with numerous (up to 43) smaller and stiff biserial branches (brachioles), organized in heart-shaped array between the V-shaped arms. The theca is globular to ellipsoidal with primary and smaller secondary plates, both bearing ridged sutural pores (or epispires). The stem is very thin and cylindrical with multiple plates which tend to be rounded near the attachment with the theca. The morphology of the basal part of the stem, is not known.

Abundance:

This species is very rare, only a dozen complete to nearly complete specimens are known.

Maximum Size:
210 mm

Ecology:

Ecological Interpretations:

Lyracystis was most likely attached to the sea floor by a stalk and fed by capturing small water-borne particles with its thin, tendril-like arms. Food particles were transported from the arms to food grooves (ambulacrum) into a central mouth at the top of the theca.

References:

SPRINKLE, J. 1973. Morphology and evolution of blastozoan echinoderms. Harvard University, Museum of Comparative Zoology Special Publication: 1-284 p.

SPRINKLE, J. AND D. COLLINS. 2006. New eocrinoids from the Burgess Shale, southern British Columbia, Canada, and the Spence Shale, northern Utah, USA. Canadian Journal of Earth Sciences, 43: 303-322.

Other Links:

None