The Burgess Shale

Diraphora bellicostata

A brachiopod with a ridged appearance

3D animation of Diraphora bellicostata and other brachiopods (Acrothyra gregaria, Micromitra burgessensis, Nisusia burgessensis, and Paterina zenobia).

Animation by Phlesch Bubble © Royal Ontario Museum

Taxonomy:

Kingdom: Animalia
Phylum: Unknown
Class: Rhynchonellata (Order: Orthida)
Remarks:

Diraphora belongs to the Family Bohemiellidae.

Species name: Diraphora bellicostata
Described by: Walcott
Description date: 1924
Etymology:

Diraphora – from the Greek deiras, “ridge,” and phoras, “bearing.”

bellicostata – from the Latin bellus, “beautiful,” and costatus, “ribbed.”

Type Specimens: Syntypes –USNM69731-69737 in the National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
Other species:

Burgess Shale and vicinity: none to date. The Burgess Shale brachiopods in particular from the Trilobite Beds on Mount Stephen need to be re-examined (see also Brief history of research).

Other deposits: Several species are known in North America and Australia.

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:

Originally assigned to Eoorthis by Walcott (1924), this species was subsequently reassigned by Bell as the type species of a new genus, Diraphora (Bell, 1941). Diraphora bellicostata has not been studied since its original description by Walcott in 1924. Walcott’s description is cursory, inadequately diagnosing the specimen, and no types were designated. The species needs to be redescribed.

Description:

Morphology:

Diraphora bellicostata possesses sharp ornamental lines (costae) radiating on its surface from the hinge. The shells would have been articulated with short and small teeth, like in Nisusia, a comparable form from the Burgess Shale. No preserved soft parts are known and the shell was originally mineralized.

Abundance:

Diraphora bellicostata is known from several hundred specimens in the Walcott Quarry and is the most abundant of all brachiopods but still represents a relatively small fraction of the entire fauna (<1.3%) (Caron and Jackson, 2008).

Maximum Size:
10 mm

Ecology:

Life habits: Epibenthic, Sessile
Feeding strategies: Suspension feeder
Ecological Interpretations:

It is likely that Diraphora had a short, stout pedicle from which it was attached to the substrate. Some specimens are attached to spicules of sponges in particular of Pirania. Other organisms (for example Mackenzia) attached themselves on isolated valves of Diraphora (representing dead individuals), which they used as anchors. Extraction of food particles from the water would have been possible thanks to a filter-feeding apparatus (located between the shells) called a lophophore.

References:

BELL, C. W. 1941. Cambrian Brachiopoda from Montana. Journal of Paleontology, 15: 193-255.

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. D. 1924. Cambrian and Ozarkian Brachiopoda. Cambrian Geology and Paleontology IV. Smithsonian Miscellaneous Collections, 67: 477-554.

Other Links:

None