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Priscansermarinus barnetti

An enigmatic barnacle-like animal

Image of Priscansermarinus barnetti.

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Priscansermarinus barnetti (ROM 36064) – Holotype (specimen A). Slab with 62 individuals including the holotype (white frame to the left and close up to the right). Specimen length (holotype) = 32 mm. Specimen dry – polarized light (both images). Walcott Quarry talus.

© Royal Ontario Museum. Photos: Jean-Bernard Caron

Media 1 of 2 for Priscansermarinus barnetti Photo
Media 2 of 2 for Priscansermarinus barnetti Photo

Taxonomy

Kingdom:

Animalia

Phylum:

Unknown

Class:

Non applicable

Affinity:

Originally proposed as a crustacean arthropod and a possible member of the pedunculate lepadomorph barnacles within Maxillopoda (Subclass Thecostraca) (Collins and Rudkin, 1981), its affinities have since been questioned and remain equivocal.

Species name:

Priscansermarinus barnetti

Described by:

Collins and Rudkin

Description date:

1981

Etymology:

Priscansermarinus – from the Latin priscus “of ancient times;” anser, “goose” and marinus, “sea,” (together forming “sea goose”) in reference to the modern goose barnacles.

barnetti – after Robert Barnett, member of the 1975 ROMexpedition, who found the first specimens.

Type Specimens:

Holotype –ROM36064a in the Royal Ontario Museum, Toronto, Ontario, Canada

Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

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Age

Period:

Middle Cambrian, Bathyuriscus-Elrathina Zone (approximately 505 million years ago).

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Localities

Principal localities:

The Walcott and Raymond Quarries on Fossil Ridge, Mount Field.

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History of Research

Brief history of research:

The “discovery” slab bearing 62 individuals of a previously unknown organism was found by Robert Barnett in talus (scree) beneath the Walcott Quarry level during the ROM’s inaugural Burgess Shale expedition in 1975. Priscansermarinus barnetti was described and named in 1981, and interpreted as a probable stalked (pedunculate) lepadomorph (goose) barnacle, pending recovery of additional specimens preserving definitive characters. The barnacle, and even the arthropod, affinities of Priscansermarinus have since been questioned (Briggs, 1983; Briggs et al., 2005).

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Description

Morphology:

Priscansermarinus consists of two primary components – an ovate triangular shaped, laterally compressed “body,” and a short, thick “stalk.” The body region shows a highly reflective centralized subtriangular region that was originally interpreted as evidence for a thin non-biomineralized external “plate” on either side of the body. This is now recognized to be an internal structure of greater anatomical complexity. The stalk, or stolon, which appears to emerge from the body rather than blend into it, is cylindrical in shape and at least moderately flexible; the distal end bears a terminal disc exhibiting a radiating pattern. In most known specimens, the stalk comprises slightly more than half of the total length of the animal.

Abundance:

Moderately common at some Raymond Quarry levels; uncommon elsewhere.

Maximum size:

50 mm

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Ecology

Life habits:

Epibenthic, sessile

Feeding strategies:

Suspension feeder

Ecological Interpretations:

This species is too poorly known to describe its ecology with great certainty. The terminal disk at the base of its stolon was probably used for anchoring the animal in or on the mud. Without any apparent tentacles and obvious feeding structures, a suspension feeding mode of life is a strong possibility.

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References

Bibliography:

BRIGGS, D. E. G. 1983. Affinities and early evolution of the Crustacea: the evidence of the Cambrian fossils, p. 1-22. In F. R. Schram (ed.), Crustacean Phylogeny. Balkema, Rotterdam.

BRIGGS, D. E. G., M. D. SUTTON AND D. J. SIVETER. 2005. Metamorphosis in a Silurian barnacle. Proceedings of the Royal Society, B, 272: 2365-2369.

COLLINS, D. AND RUDKIN, D. M. 1981. Priscansermarinus barnetti, a probable lepadomorph barnacle from the Middle Cambrian Burgess Shale of British Columbia. Journal of Paleontology, 55: 1006-1015.

Other links:

None

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