The Burgess Shale

Bosworthia simulans

A presumed red alga composed of thick branches

Bosworthia simulans (USNM 35426) – Syntype. Specimen showing multiple branches emerging from a central axis (near the middle). Approximate specimen length (of the most complete branch) = 70 mm. Specimen dry – polarized light. Walcott Quarry.

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


Kingdom: Plantae
Phylum: Rhodophyta
Higher Taxonomic assignment: Non applicable
Species name: Bosworthia simulans

No revisions of this alga have been published since its original description by Walcott (1919) and its affinities remain uncertain.

Described by: Walcott
Description date: 1919

Bosworthia – from Mount Bosworth (2,769 m) on the British Columbia-Alberta border, in Yoho and Banff National Parks. Named in 1904 after George Morris Bosworth, the Canadian Pacific Railway freight traffic manager from 1896-1901.

simulans – from the Latin simulans, “make like” or “imitate”. The name refers to the repeated shape of the subdividing branches.

Type Specimens: Bosworthia simulans – Syntypes –USNM35426-35427 (Bosworthia simulans); HolotypeUSNM35428 (Bosworthia gyges) in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
Other species:

Burgess Shale and vicinity: Bosworthia gyges Walcott, 1919.

Other deposits: none.

Age & Localities:

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:

Bosworthia was described by Charles Walcott (1919) as a possible red alga. However, like all the algae from the Burgess Shale, it awaits a modern redescription.



This alga is composed of a long flexible central thallus, from which long and relatively thick branches emerge. These branches may further subdivide into smaller branches and narrow along their length. Walcott (1919) described B. gyges as having more rigid branches than B. simulans. He hypothesized that there was probably a central stem and attachment structure that would have allowed the alga to attach to the seafloor although this structure has not yet been observed in the fossils. Bosworthia has been described from fragments only (up to 8 cm in length) and the complete size is unknown.


Bosworthia represents less than 0.04% of the Walcott Quarry community (Caron and Jackson, 2008).

Maximum Size:
82 mm


Life habits: Epibenthic, Sessile
Feeding strategies: Primary producer
Ecological Interpretations:

The mode of life of this alga is uncertain. Its structure suggests it was attached to the sea floor within the photic zone, rather than being free floating.


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

WALCOTT, C. 1919. Cambrian Geology and Paleontology IV. Middle Cambrian Algae. Smithsonian Miscellaneous Collections, 67(5): 217-260.

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