The Burgess Shale

Tubulella flagellum

Tubulella flagellum (ROM 59942) – Proposed Lectotype. Figures 1a of Matthew (1899) and photograph of original specimen (right). Approximate specimen length = 80 mm. Specimen dry – direct light. Trilobite Beds on Mount Stephen.

© ROYAL ONTARIO MUSEUM. PHOTOS: JEAN-BERNARD CARON

Taxonomy:

Class: Unranked clade (stem group cnidarians)
Remarks:

This fossil was originally thought to represent the tube of some sedentary polychaete worms (Matthew, 1899; Howell, 1949), but has more recently been compared to 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).

Species name: Tubulella flagellum
Described by: Matthew
Description date: 1899
Etymology:

Tubulella – from the latin tubulus, “tube, or tubule,” and the suffix –ella, denoting “little.”

flagellum – the Latin for “whip,” in allusion to the long, tapering form of the tubular theca.

Type Specimens: Syntype–ROM59942 in the Royal Ontario Museum, Toronto, ON, Canada.
Other species:

Burgess Shale and vicinity: Many shared similarities suggest that other thecate Burgess Shale fossils such as Byronia annulataSphenothallus sp., Cambrorhytium major, and Cfragilis may be related to Tubulella.

Other deposits: Other species occur worldwide in rocks from the Cambrian period.

Age & Localities:

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

The Trilobite Beds, Tulip Beds (S7) and additional smaller localities on Mount Stephen. The Walcott and Raymond Quarries on Fossil Ridge, Mount Odaray and Monarch Cirque.

History of Research:

Brief history of research:

In August 1887 the Toronto meeting of the British Association for the Advancement of Science was followed by a special geological rail tour to western Canada organized by Byron Edmund Walker (a prominent Canadian banker). One of the excursion highlights was a visit to the Mount Stephen Trilobite Beds, after which Walker loaned his personal collection of Mount Stephen fossils to Canada’s leading Cambrian palaeontologist, George F. Matthew, of Saint John, New Brunswick. In 1899, Matthew published a series of new descriptions based on this material, including Urotheca flagellum, a rare form he interpreted as whip-shaped worm tube, illustrated in two engravings. Walker donated these fossils to the University of Toronto in 1904, and in 1913 they were transferred to the new Royal Ontario Museum of Palaeontology. In 1949, American palaeontologist B. F. Howell found that Matthew’s genus name Urotheca was already in use for a living reptile, so he substituted it for the new name Tubulella. Subsequently, this and similar fossils were reinterpreted as cnidarian polyp thecae. The single best specimen of Walker’s Urotheca flagellum remained unrecognized until it was “rediscovered” in the ROM collections in 2010.

Description:

Morphology:

The chitinous or chitinophosphatic tube (theca) of Tubulella flagellum is a very long and slender cone, with a maximum diameter of about 4 mm. The thecae may be almost straight, or show varying degrees of curvature. The thecal wall is relatively thick and often appears densely black against the shale matrix. The external surface shows very fine transverse growth lines, but usually no strong annular ridges. Often, two or more lengthwise creases or ridges were formed as the result of the crushing and compaction of the tube’s original circular or oval cross section. Some specimens possess a combination of features seen in Tubulella and Byronia, with very narrow thecae bearing both annulae and longitudinal creases. Small clusters of such Tubulella-like thecae are occasionally found closely associated with Byronia annulata, but it is not known whether these were asexually generated “buds” or discrete organisms growing attached to the larger tubes. No soft tissues of Tubulella flagellum have been described to date.

Abundance:

Uncommon in the Trilobite Beds on Mount Stephen. Relatively common in the Walcott Quarry on Fossil Ridge where it represents about 0.25% of the specimens in the community (Caron and Jackson, 2008).

Maximum Size:
100 mm

Ecology:

Ecological Interpretations:

The theca of Tubulella was likely attached to the substrate using an apical disc which is usually broken off. The absence of soft tissue preservation makes the assignment to a particular feeding strategy tentative. By comparison with forms such as Cambrorhytium, a carnivorous or suspension feeding habit seems possible.

References:

BISCHOFF, C. O. 1989. Byroniida new order from early Palaeozoic strata of eastern Australia (Cnidaria, thecate scyphopolyps). Senkenbergiana Lethaea, 69(5/6): 467-521.

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

HOWELL, B. F. 1949. New hydrozoan and brachiopod and new genus of worms from the Ordovician Schenectady Formation of New York. Bulletin of the Wagner Free Institute of Science, 24(1): 8 pp.

MATTHEW, G. F. 1899. Studies on Cambrian faunas, No. 3. Upper Cambrian fauna of Mount Stephen, British Columbia. The trilobites and worms. Transactions of the Royal Society of Canada, Series 2, 4: 39-66.

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

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

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

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

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:

Class: Unranked clade (stem group cnidarians)
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).

Species name: Thaumaptilon walcotti
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:

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:

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:

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

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

Class: Unranked clade (stem group cnidarians)
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).

Species name: Sphenothallus sp.
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 annulataCambrorhytium majorCfragilis 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:

Period:
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:

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

Cambrorhytium major

Cambrorhytium fragilis (USNM 57626) – Holotype, part and counterpart. Complete tube in close proximity to an isolated claw of Anomalocaris. Specimen length = 25 mm. Specimen dry – direct light (left), dry – polarized light (middle, left), wet – direct light (top right) and wet – polarized light (bottom right). Trilobite Beds on Mount Stephen.

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

 

Taxonomy:

Class: Unranked clade (stem group cnidarians)
Remarks:

On account of its similarity to the genus Byronia and its polyp-like tentacles, Cambrorhytium is thought to be related to a group of cnidarian known as the conulariids. However, no distinctive features that would categorically place it in the Cnidaria are preserved.

Species name: Cambrorhytium major
Described by: Walcott
Description date: 1908
Etymology:

Cambrorhytium – from the name of the Cambrian period, and the Latin rhytium, “drinking horn.”

major – from the Latin major, “large.”

Type Specimens: Holotypes –USNM96542 (C. major) andUSNM57626 (C. fragilis) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: C. fragilis (Walcott, 1911) Conway Morris and Robinson, 1988 from the Mount Stephen Trilobite Beds and the Walcott Quarry.

Other deposits: C. elongatum (Steiner et al., 2005) from Lower Cambrian deposits in Chengjiang County; Haikou and Jingmacun of Kunming district; and the Niutitang Formation of Zhongnan, Zunyi County, Guizhou, China; C. fragilis is also known from the Lower Cambrian Latham Shale (Waggoner and Hagadorn, 2005); C. major from the Marjum Formation (uppermost Middle Cambrian, Utah, Conway Morris and Robison, 1998).

Age & Localities:

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

Burgess Shale and vicinity: The Trilobite Beds on Mount Stephen and the Walcott and Raymond Quarries on Fossil Ridge.

Other deposits: C. fragilis is also known from the Lower Cambrian Latham Shale (Waggoner and Hagadorn, 2005); C. major from the Marjum Formation (uppermost Middle Cambrian, Utah, Conway Morris and Robison, 1998).

History of Research:

Brief history of research:

The genus Cambrorhytium was erected in 1988 by Conway Morris and Robinson to accommodate two problematic fossil species now known as Cambrorhytium major and C. fragilis. Walcott (1908) figured a specimen of C. major from the Mount Stephen Trilobite Bedsin the hyolith genus Orthotheca on account of its triangular shape. Thanks to new material discovered in the Walcott Quarry, Walcott (1911) reconsidered this Mount Stephen specimen to belong to a new genus Selkirkia (S. major) thought to be the tube of a polychaete worm at the time (Walcott, 1911). The original Mount Stephen Selkirkia major specimen first figured by Walcott in his 1908 publication lacked soft-parts, but further specimens of this species from the Walcott Quarry clearly showed an affinity with the priapulid worms (Conway Morris, 1977). On re-examination, the holotype of Selkirkia major, and some specimens of the two other species of Selkirkia erected by Walcott (1911) were demonstrably not priapulids. The non-priapulid Selkirkia species were re-homed in the new genus Cambrorhytium.

Description:

Morphology:

The chitinous and probably non-mineralized conical and slightly curved tube of Cambrorhytium major gradually expands from a point to a smooth circular opening that lacked a covering or closure. Five fleshy tentacle-like structures emerged from this opening. The organism grew periodically, adding to the cone at its open end, thus leaving a series of “growth rings.” Although it grew to over six cm in length, the average size is 4 cm and most specimens are at the smaller end of the size range. The earliest stages of growth are less regular than the later, so the base of the cone is usually a little wiggly.

C. major is typically larger and more slender than C. fragilis, whose growth-rings are less pronounced. C. fragilis is usually more reflective than C. major, which may represent a difference in original composition or simply a preservational bias.

Abundance:

Cambrorhytium major is rare, known from only a few dozen specimens, but C. fragilis is more common. In the Walcott Quarry, both species represent around 0.35% of the total counts of fossils (Caron and Jackson, 2008).

Maximum Size:
65 mm

Ecology:

Ecological Interpretations:

The organism appears to have reproduced sexually rather than by budding. Although Cambrorhytium was bottom-dwelling, there is no indication of any anchoring structure, suggesting that it might have sat partially within the sediment. Cambrorhytium is thought to have been either a suspension feeder or a carnivore on the basis of its probable tentacles and presumed cnidarian affinity.

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. 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.

STEINER, M., M. ZHU, Y. ZHAO AND B.-D. ERDTMANN. 2005. Lower Cambrian Burgess Shale-type fossil associations of South China. Palaeogeography, Palaeoclimatology, Palaeoecology, 220(1-2): 129-152.

WAGGONER, B. AND J. W. HAGADORN. 2005. Conical fossils from the Lower Cambrian of Eastern California. PaleoBios, 1: 1-10.

WALCOTT, C. D. 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.

Other Links:

None

Byronia annulata

Byronia annulata (ROM 56648). Plate 1, figures 9 and 9a of Walcott (1908) and counterpart of original specimen collected in 1975 from the Trilobite Beds on Mount Stephen. (The part is at the Smithsonian Institution). Approximate specimen length = 95 mm. Specimen dry – direct light. Trilobite Beds on Mount Stephen.

© Royal Ontario Museum. Photos: Jean-Bernard Caron

Taxonomy:

Class: Scyphozoa? (Order: Byroniida, stem group cnidarians)
Remarks:

Byronia represents the purported sessile polyp stage of a scyphozoan jellyfish that builds tapered, chitinous tubes fixed to the substrate by an attachment disc (Zhu et al., 2000).

Species name: Byronia annulata
Described by: Matthew
Description date: 1899
Etymology:

Byronia – for Byron Edmund Walker (1848-1924), Canadian banker, amateur palaeontologist, and co-founder of the Royal Ontario Museum.

annulata – from the Latin annulatus, “ring-like,” in reference to distinct annular (transverse) ridges.

Type Specimens: Syntype –ROM59941 in the Royal Ontario Museum, Toronto, ON, Canada.
Other species:

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

Other deposits: B. natus from the Kaili Formation (Zhu et al., 2000). Other species occur in the Cambrian worldwide, including in Australia, in particular B. displosa, B. mirrabookaensis and B. petila (Bischoff, 1989).

Age & Localities:

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

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

History of Research:

Brief history of research:

On August 1887, the Toronto meeting of the British Association for the Advancement of Science was followed by a special geological rail tour to western Canada organized by Byron Edmund Walker (a prominent Canadian banker). One of the excursion highlights was a visit to the Mount Stephen Trilobite Beds, after which Walker loaned his personal collection of Mount Stephen fossils to Canada’s leading Cambrian palaeontologist, George F. Matthew, of Saint John, New Brunswick. In 1899, Matthew published a series of new descriptions based on this material, including Byronia annulata, named in gratitude for Walker’s generosity. Matthew considered this rare form to be a flattened, conical worm tube, and illustrated the only complete specimen (which would have been considered the holotype) in an engraving. Walker donated his entire fossil collection to the University of Toronto in 1904, and in 1913 it was transferred to the new Royal Ontario Museum of Palaeontology. Unfortunately, the single complete specimen of Byronia annulata described by Matthew remained unrecognized until it was “rediscovered” in the ROM collections in 2009. In the meantime, Byronia had been reinterpreted as the theca of a cnidarian polyp based on specimens from other sites.

Description:

Morphology:

The chitinous or chitinophosphatic tube (theca) of Byronia annulata is long and conical, originally circular or oval, with a cross section approaching 10 mm in diameter. Thecae may be almost straight or may show varying degrees of curvature, and are almost always flattened by compression. Preservation of the multilamellar thecal wall is occasionally quite good, with patches of dark, glossy material contrasting strongly against the shale matrix. The external surface shows distinctive closely-spaced annular (transverse) ridges with very fine longitudinal (lengthwise) ridges between them. Complete thecae may show a small attachment disc at the narrow end. Individuals or clusters of smaller, narrower thecae resembling a form called Tubulella flagellum are occasionally found closely associated with Byronia, but it is not known if these grew attached to, or clonally “budded” from, the larger tubes. As yet, no soft tissues of Byronia annulata have been described.

Abundance:

Rare, known mostly from the Trilobite Beds on Mount Stephen.

Maximum Size:
100 mm

Ecology:

Ecological Interpretations:

The theca of Byronia was likely attached to the substrate using an apical disc which is usually broken off. The absence of soft tissue preservation makes the assignment to a particular feeding strategy tentative. By comparison with forms such as Cambrorhytium, a carnivorous or suspension feeding habit seems possible.

References:

BISCHOFF, C. O. 1989. Byroniida new order from early Palaeozoic strata of eastern Australia (Cnidaria, thecate scyphopolyps). Senkenbergiana Lethaea, 69(5/6): 467-521.

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.

MATTHEW, G. F. 1899. Studies on Cambrian faunas, No. 3. Upper Cambrian fauna of Mount Stephen, British Columbia. The trilobites and worms. Transactions of the Royal Society of Canada, Series 2, 4: 39-66.

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

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

ZHU, M.-Y., H. VAN ITEN, R. S. COX, Y. L. ZHAO, 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

Mackenzia costalis

3D animation of Mackenzia costalis.

ANIMATION BY PHLESCH BUBBLE © ROYAL ONTARIO MUSEUM

Taxonomy:

Class: Anthozoa? (Order: Actiniaria(?), stem group cnidarians)
Remarks:

Mackenzia is thought to be a cnidarian (a group which includes modern coral and jellyfish) and appears most similar to modern sea anemones (Conway Morris, 1993).

Species name: Mackenzia costalis
Described by: Walcott
Description date: 1911
Etymology:

Mackenzia – from Mount Mackenzie (2,461 m) near Revelstoke, southwest of the Burgess Shale. Mount Mackenzie was named in honor of Alexander Mackenzie (1822-1892), Canada’s 2nd Prime Minister.

costalis – from the Latin costalis, “pertaining to ribs.” The name refers to the lineations along the length of the animal.

Type Specimens: Lectotype –USNM57556 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.

History of Research:

Brief history of research:

Mackenzia was first described as a holothurian, a group of echinoderms commonly known as the sea-cucumbers (Walcott, 1911). Additional fossils collected by the Geological Survey of Canada and restudy of Walcott’s collection led Conway Morris (1989, 1993) to reinterpret this animal as a cnidarian.

Description:

Morphology:

Mackenzia is a large saclike animal, up to 16 cm in height, which was anchored to hard substrates with a disc or holdfast via a short stalk; it probably stood upright. The surface of the body is folded longitudinally into 8-10 ridges. There is a large gut cavity and some evidence of internal partitioning, but little else is known of the anatomy. Tentacles are absent; the mouth was probably at the end opposite the stalk.

Abundance:

Mackenzia is very rare and represents only 0.03% of the Walcott Quarry community (Caron and Jackson, 2008).

Maximum Size:
200 mm

Ecology:

Ecological Interpretations:

Mackenzia probably lived on the seabed and may have attached to animal remains such as brachiopod shells for stability. Its mode of feeding is uncertain.

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. 1989. Burgess Shale faunas and the Cambrian explosion. Science, 246: 339-346.

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

WALCOTT, C. D. 1911. Middle Cambrian holothurians and medusae. Cambrian Geology and Paleontology II. Smithsonian Miscellaneous Collections, 57(3): 41-68.

Other Links:

None