Fossil Gallery
Mackenzia costalis
A Burgess Shale sea anemone-like animal
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Photo Kingdom:
Animalia
Phylum:
Cnidaria
Class:
Anthozoa? (Order: Actiniaria(?), stem group cnidarians)
Affinity:
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 – USNM 57556 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:
Burgess Shale and vicinity: none.
Other deposits: none.
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.
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.
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
Life habits:
Epibenthic, sessile
Feeding strategies:
Suspension feeder?, carnivorous?
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.
Bibliography:
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
