Lower Cambrian melanosclerites and foraminiferal linings from the Lontova Formation, St. Petersburg, Russia

This paper documents the first evidence for melanosclerites and foraminiferal test-linings from the Cambrian. While agglutinated foraminifera are known from the Precambrian–Cambrian transition, their tests are delicate and not commonly recovered from acid-digested samples. The material presented herein represents the organic test-linings, which preserve sufficient detail of the internal morphology of the foraminiferal test wall and gross morphology to allow identification to generic level. The occurrence of melanosclerites documented herein, extends their lower range from the Middle Ordovician to the Lower Cambrian and includes Semenola semen Schallreuter 1981, Melanosteus sp. Eisenack 1942 and Melanoclava sp. Eisenack 1942. Foraminiferal taxa include Psammosphaera Schulze 1875, Thurammina? Brady 1879, and a small tubular form (Bathysiphon?), which supplements the previously described records of Platysolenites spp., Spirosolenites spiralis Glaessner 1979 and Psammosphaera sp., which are known from their agglutinated tests rather than the test-lining. This also extends the first occurrence datum of Psammosphaera and Thurammina? to the Platysolenites partial range zone of the Lower Cambrian.