The Givetian (Middle Devonian) antiarch Asterolepis orcadensis was first described in 1932 based on a limited amount of material. Newly collected material has allowed the head to be described in more detail, especially the premedian plate which has an embayment at the centre of the anterior edge. Also, the anterior section of supra-orbital sensory line has been identified on the premedian plate. Other elements newly described include the pectoral appendages which are shown to be quite broad at their proximal ends. The anterior ventro-lateral plate has been described in detail for the first time, particularly structures associated with the attachment of pectoral appendages. The posterior median dorsal plate has been shown not to have had a more pointed posterior edge as depicted in the 1932 description, but a flatter posterior edge reminiscent of Asterolepis saevesoederberghi which is shown to be closely related to A. orcadensis. The shortness of the posterior median dorsal plate has emphasised the broadness of the whole armour, making A. orcadensis one of the broadest species of Asterolepis. Whilst A. orcadensis is endemic to the Orcadian Basin of northern Scotland, it fits into a biostratigraphical column at the same level as A. saevesoederberghi so strengthening the evidence of a close relationship between these two forms.

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The Middle Devonian lacustrine sediments of Orkney, off the northeast Scottish mainland, are composed largely of the Lower and Upper Stromness Formations and overlying Rousay Formation. These three formations have been subdivided and defined by vertebrate biostratigraphic biozones with recent division of the Rousay Formation into three further units based on characteristic fish fossils. The division of the Rousay Formation has enabled a map to be constructed of the solid geology of the island of Westray, Orkney, based on fish identification, detailed logging of sedimentary cycles throughout the Rousay succession, parameters of divisional boundaries, and a survey of faults marking sinistral transtensional movement parallel to the Great Glen Fault. Post-Carboniferous shortening and basin inversion led to uplift, folding and reactivation of normal faults as reverse faults, to form a positive strike-slip flower structure in Westray. A suite of Permian igneous dykes intruded across Orkney include three minor offshoots in Westray. The resulting map is the first to make use of biostratigraphic units within the Rousay Flagstone which are now regarded as Members.

The only official maps to show a boundary between the Middle Devonian Stromness and Rousay Flagstones on Orkney are those published by the Geological Survey in 1932 and 1935. Since then, the difficulties of defining and locating this boundary have challenged many workers in the Orcadian Lake Basin. In 2015, the introduction of biozones by Uisdean Michie, based on fossil fish, and the recent discovery in Westray of the zone fossils Osteolepis panderi and Thursius pholidotus in a prominent fish bed across the island, has permitted the boundary for the base of the Rousay Formation to be determined in that part of Orkney. It is suggested that other characteristics of the fish bed of this rhythmic cycle of sediments, together with those in adjacent cycles, may be used as a marker for further correlation and mapping across the basin.