The Burgess Shale

Amiskwia sagittiformis

Reconstruction of Amiskwia sagittiformis.

© Marianne Collins

Taxonomy:

Kingdom: Unknown
Phylum: Unknown
Higher Taxonomic assignment: Non applicable
Species name: Amiskwia sagittiformis
Remarks:

The phylogenetic position of Amiskwia is uncertain. Despite significant objections to its traditional interpretation as a chaetognath (Conway Morris, 1977; Owre and Bayer, 1962), some workers still hold this view (Butterfield, 1990). Nemertine (Owre and Bayer, 1962) and molluscan (Chen and Huang, 2002; Chen et al., 2005) affinities have also been suggested, but not substantiated.

Described by: Walcott
Description date: 1911
Etymology:

Amiskwia – from the Cree amiskwi, “beavertail,” a name given to various topographical features in Yoho National Park.

sagittiformis – from the Latin sagitta, “arrow,” and formis, “shape,” in reference to the general outline of the animal.

Type Specimens: Lectotype – UNSM 57644 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: A. sinica (Chen et al., 2002) from the Lower Cambrian Chengjiang deposits, Yunnan, China.

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:

Described by Walcott in 1911, Amiskwia was originally interpreted as an arrow-worm (Walcott, 1911). Originally popular, this interpretation fell into disrepute after further studies (Conway Morris, 1977; Owre and Bayer, 1962), but it has more recently been reconsidered as a possible arrow-worm (Butterfield, 1990).

Description:

Morphology:

Amiskwia is a symmetrical, flattened worm. It bears a pair of lateral fins in addition to a paddle-like tail fin. A pair of small tentacles is situated on the bottom of its head, just in front of its mouth. The trace of a gut and other internal organs are preserved in the fossils.

Abundance:

A. saggitiformis is known from only a couple dozen specimens from the Walcott Quarry, comprising only 0.025% of the specimens counted (Caron and Jackson, 2008).

Maximum Size:
25 mm

Ecology:

Life habits: Unknown
Feeding strategies: Unknown
Ecological Interpretations:

The presence of fins demonstrates that Amiskwia was well adapted for swimming. Its rarity in the Burgess Shale suggests that it may have spent much of its time well above the sea bed, above the depth at which it could be caught in submarine mudslides.

References:

BUTTERFIELD, N. J. 1990. Organic preservation of non-mineralizing organisms and the Taphonomy of the Burgess Shale. Paleobiology, 16(3): 272-286.

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

CHEN, J.-Y. AND D.-Y. HUANG. 2002. A possible Lower Cambrian chaetognath (arrow worm). Science, 298(5591): 187.

CHEN, J.-Y., D.-Y. HUANG AND D. J. BOTTJER. 2005. An Early Cambrian problematic fossil: Vetustovermis and its possible affinities. Proceedings of the Royal Society B: Biological Sciences, 272(1576): 2003-2007.

CHEN, L., H. LUO, S. HU, J. YIN, Z. JIANG, Z. WU, F. LI AND A. CHEN. 2002. Early Cambrian Chengjiang fauna in Eastern Yunnan, China. Yunnan Science and Technology Press, Kunming, China, 199 p.

CONWAY MORRIS, S. 1977. A redescription of the Middle Cambrian worm Amiskwia sagittiformis Walcott from the Burgess Shale of British Columbia. Palaontologische Zeitschrift, 51(3): 271-287.

OWRE, H. B. AND F. M. BAYER. 1962. The systematic position of the Middle Cambrian fossil Amiskwia Walcott. Journal of Paleontology, 36(6): 1361-1363.

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

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Herpetogaster collinsi

3D animation of Herpetogaster collinsi.

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: Unknown
Phylum: Unknown
Higher Taxonomic assignment: Unranked clade Cambroernida (stem group ambulacrarians)
Species name: Herpetogaster collinsi
Remarks:

Herpetogaster, together with other pedunculate or discoidal fossils such as Eldonia, probably belongs in the stem group to a clade known as the Ambulacraria, represented by both echinoderms and hemichordates (Caron et al., 2010).

Described by: Caron and Conway Morris
Description date: 2010
Etymology:

Herpetogaster – from the Greek, herpo, “to creep,” and gaster, “stomach.” The name refers to the creeping aspect of the animal and the large stomach.

collinsi – after Desmond Collins, a former curator of palaeontology at the Royal Ontario Museum who led expeditions to the Burgess Shale between 1975-2000.

Type Specimens: Holotype –ROM58051 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 Walcott and Raymond Quarries on Fossil Ridge. The Collins Quarry on Mount Stephen and Stanley Glacier in Kootenay National Park.

History of Research:

Brief history of research:

Herpetogaster was described in 2010 as a possible member of the ambulacrarians (Caron and Conway Morris, 2010).

Description:

Morphology:

Herpetogaster consists of a main body with a pair of tentacles at the front and a flexible stolon. The body is divided into thirteen segments and coils clockwise when seen dorsally. The tentacles are long and flexible and branch several times. The stomach is the most conspicuous portion of the gut and is often preserved as a highly reflective film, as in Eldonia, a closely related form. The anus is terminal and the mouth is located between the tentacles. The stolon sometimes exceeds the length of the main body, and terminates with a flat disk. This structure was evidently used for anchoring the organism to the seabed, or to other organisms).

Abundance:

This animal is known from 101 specimens. Only 6 come from the Walcott Quarry, where it represents only 0.011% of the specimens counted in the community (Caron and Jackson, 2008); most specimens (68) come from the Raymond Quarry.

Maximum Size:
48 mm

Ecology:

Life habits: Unknown
Feeding strategies: Unknown
Ecological Interpretations:

Specimens of Herpetogaster were found associated with the sponge Vauxia, suggesting the animal lived on or near the seabed. It is not clear if Herpetogaster was permanently anchored, and whether or not it fed only on particulate matter in the water column, or could hunt small preys using its prehensile tentacles.

References:

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., S. CONWAY MORRIS AND D. SHU. 2010. Tentaculate fossils from the Cambrian of Canada (British Columbia) and China (Yunnan) interpreted as primitive deuterostomes. PLoS ONE, 5(3): e9586.

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Banffia constricta

Reconstruction of Banffia constricta.

© Marianne Collins

Taxonomy:

Kingdom: Unknown
Phylum: Unknown
Higher Taxonomic assignment: Unranked clade vetulicolid (Order: Banffozoa)
Species name: Banffia constricta
Remarks:

Banffia is regarded to be an end member of a larger group called the vetulicolids, in its own class, the Banffozoa (Caron, 2005). Contrary to most vetulicolids, Banffia lacks anterior grooves and lateral pouches. The position of the vetulicolids is still uncertain (Aldridge et al., 2007).

Described by: Walcott
Description date: 1911
Etymology:

Banffia – from the town of Banff in Banff National Park. The name comes from the County of Banff in Scotland and was given by Sir William Van Horne in 1888.

constricta – from the Latin con, “a cone,” and strictus, “tight.” The name refers to the constriction in the middle of the cone-shaped body.

Type Specimens: Lectotype –USNM57638 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none.

Other deposits: Banffia confusa from the Lower Cambrian Chengjiang Fauna in China (Chen et al., 1996).

Age & Localities:

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

The Raymond and Collins Quarries on Fossil Ridge.

History of Research:

Brief history of research:

Banffia was first described by Walcott based on a half a dozen specimens in a 1911 monograph dealing with various Burgess Shale worms. Walcott placed Banffia in a now defunct group called the Gephyrea with other vermiform fossils such as Pikaia and Oesia. Banffia was later considered to be a Problematica i.e., organism of unknown affinity (Briggs and Conway Morris, 1986). Caron (2005) redescribed this organism based on the original Walcott material and more than 300 specimens collected by the Royal Ontario Museum.

Description:

Morphology:

The body can reach up to 10 cm in length and is divided into two broad sections of roughly equal length. The front section has two fused and smooth carapaces forming approximately a tube in cross section. The posterior section is finely segmented with up to 50 segments and is clearly more flexible than the anterior section. The mouth is at the front with a crown-like element around it and the anus is terminal and ends between a small caudal notch. Possible small diverticulae are present around the gut. The entire body is twisted along a spiral, turning clockwise as seen from the front. As a result of this body plan, constrictions are evident in the anterior and posterior parts, especially when specimens are preserved laterally.

Abundance:

Overall Banffia is rare. A few specimens are known from the Raymond Quarry but Banffia is more common in the upper layers of the Collins Quarry on Fossil Ridge. A single slab (350 cm²) from this locality shows more than 60 specimens preserved on it.

Maximum Size:
105 mm

Ecology:

Life habits: Unknown
Feeding strategies: Unknown
Ecological Interpretations:

The lack of appendages and the bulky anterior section suggest the animal was not a swimmer but lived at the bottom of the sea on the mud itself. The flexible posterior section of the animal would have helped in locomotion. The presence of mud in the gut suggests the animal ate small particles of organic matter present in the flocculent layer of the mud. However because of the large anterior carapaces, this animal was probably not an efficient burrower.

References:

ALDRIDGE, R. J., X. G. HOU, D. J. SIVETER, D. J. SIVETER AND S. E. GABBOTT. 2007. The systematics and phylogenetic relationships of vetulicolians. Palaeontology, 50: 131-168.

BRIGGS, D. E. G. AND S. CONWAY MORRIS. 1986. Problematica from the Middle Cambrian Burgess Shale of British Columbia, p. 167-183. In A. Hoffman and M. H. Nitecki (eds.), Problematic fossil taxa (Oxford Monographs on Geology and Geophysics No. 5). Oxford University Press and Clarendon Press, New York.

CARON, J.-B. 2005. Banffia constricta, a putative vetulicolid from the Middle Cambrian Burgess Shale. Transactions of the Royal Society of Edinburgh, 96: 95-111.

CHEN, J. Y., G. Q. ZHOU, M. Y. ZHU AND K. Y. YEH. 1996. The Chengjiang biota a unique window of the Cambrian explosion. National Museum of Natural Science Taiwan, Taichung, 230 p.

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

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