Jurassic Period, 199-145 million years BP. A pair of cut and polished freestanding slabs of Marston Magna marble, containing a number of Promicroceras marstonense ammonites. 1.7 kg total, 18cm each (7"). From the private collection of Edward Owens of Cheshire, UK; acquired on the UK fossil market from 2010; from Marston Magna, Somerset, UK. [2]