Dineley, D. & Metcalf, S. GCR Editor: D. Palmer. 1999. Fossil Fishes of Great Britain. Geological Conservation Review Series No. 16. JNCC, Peterborough, ISBN 1 86107 470 0.
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A rich mid-Silurian fish fauna, consisting of nine species of thelodonts, anaspids and cephalaspids, has been found at this site. It has provided type specimens of three species of thelodonts Lanarkia horrida, L. spinosa and L. spinulosa.
Two fish beds are exposed on Birkenhead Burn in the Lesmahagow inlier of Strathclyde, one being 1.0–1.2 m thick, the other 4.6 m. They were considered by Jennings (1961) to be of Slot Burn Formation age. Peach and Horne (1899) first described the site, and remarked on the constant association of the fish fauna with eurypterids in the upper fish bed.
The fish beds are grey laminated mudstones, the fishes and eurypterid remains being preserved as thin grey to black films. The geology, stratigraphical relations and fish fauna of the site are described in the Slot Burn report (q.v.).
The Birkenhead Burn fish beds are comparable to those from Slot Burn (q.v.), and may belong to the Slot Burn Formation, but this correlation is uncertain. Differences in the composition of the fauna and some stratigraphical uncertainties suggest that the fauna may be of slightly different age, i.e. equivalent to the fish beds in the Dippal Burn Formation.
An outstanding fossil fish site, the conservation value of which lies in the richness of its fauna of thelodonts, anaspids, and cephalaspids, the site forms part of the network of agnathan-bearing localities of Silurian age in the Midland Valley of Scotland.