Placing the Scottish Romer's Gap tetrapods within a Tournaisian time frame

ABSTRACT A number of early tetrapods occur in different localities from the Ballagan Formation in Scotland. These localities are within the 12 Myr time duration of the Tournaisian so it is important to be able to place them within a chronology to better understand the evolutionary relationships of the tetrapods. Palynology is used to recognise distinct assemblages in the Norham West Mains Farm borehole and the Burnmouth coastal section which become a composite standard. The Willie's Hole tetrapods ( Koilops , Mesanerpeton and Perittodus ) come from the lower part of the Ballagan Formation with Auchenreoch Glen ( Pederpes ) somewhat higher. The oldest tetrapods are from the Harbour beds at Burnmouth with the Ross end cliffs tetrapods ( Aytonerpeton , Diploradus and Ossirarus ) the youngest assemblage. It is not possible to place the Coldstream tetrapods as the spore assemblage is low diversity. Tantallognathus from Tantallon is early Viséan in age. Occidens portlocki , an isolated partial tetrapod jaw from a historic collection in Northern Ireland, is not of Tournaisian age and hence not from within Romer's Gap, but it can be dated as Brigantian (latest Viséan) age. The other significant Romer's Gap locality from Blue Beach, Nova Scotia, Canada, is different in age span and palaeoenvironment.