Arcoscalpellum quadratum
Arcoscalpellum quadratum
Summary
Arcoscalpellum quadratum was a stalked barnacle. Instead of crawling across the seabed, it lived fixed in one place by a flexible stalk, raising its plated body into the water and sweeping microscopic food from passing currents with feathery feeding limbs.
Stalked barnacles could colonise shells, driftwood and other firm surfaces in an otherwise soft muddy sea. Their presence gives a glimpse of the small suspension-feeding communities that lived attached to objects on the London Clay seabed, a very different lifestyle from the mobile crabs and lobsters around them.
Quick Identification
Look for: a robust, distinctly quadrate stalked-barnacle plate with the proportions and ridge pattern characteristic of Arcoscalpellum; isolated worn plates should be compared directly with Gale’s figured material.
Diagnostic Features
- Fossil consists of calcitic capitular plates rather than a crab or lobster carapace.
- Diagnostic plates have a comparatively quadrate outline.
- Plate margins and growth ridges produce a regular, strongly geometric form.
- Plate proportions differ from the smaller calanticid barnacles in the same fauna.
- Species-level identification depends on plate identity and complete outline; broken plate fragments are often only identifiable as stalked barnacle.
Fossil Details
Similar Species
Recorded Fossil Sites
London Clay Formation
Synonyms & Previous Names
References
- A. S. Gale. (2025). British Fossil Cirripedia. Part 2. Calanticomorpha, Scalpellomorpha. Monograph of the Palaeontographical Society, 179(671), 105–193 View reference
- Thomas Bell. (1857). A monograph of the fossil malacostracous Crustacea of Great Britain. Part I. Crustacea of the London Clay. Monograph of the Palaeontographical Society, 10, i–viii, 1–44. Palaeontographical Society, London View reference