Illustration of a generalized spinicaudatan "clam shrimp". By Sarah Lyn Boyce as part of a PEET project funded by a U.S. National Science Foundation grant (DEB 9978193) to Joel W. Martin, Natural History Museum of Los Angeles County. All rights reserved.

Asmussia murchisoniana

This tiny branchiopod crustacean can be found in all Devonian sediments, and indicates a shallow water environment. It is common in the Upper Stromness and Rousay Flagstone group. Depending on the type of sediment and the conditions of fossilization Asmussia murchisoniana shows as a tiny (few mm) thin valve often with growth lines (concentric rings) visible.

The crustacean belongs to the conchostracans or commonly called clam shrimps (the shrimp is housed between to chitin valves). Conchostracans occur on all continents and have a full range from the Palaeozoic up to recent time. They are filter feeders but also scrape and tear their food and scavenge on all organisms in their environment. They live in temporary pools or other shallow water conditions.

Slab with many specimens of Asmussia

Close up of slab with Asmussia

Many specimens together

Many specimens together

Drawing and reconstruction of Asmussia (after Rupert Jones, 1862).

Drawing of Asmussia (after Rupert Jones, 1862).