The Edge Hill ridge in southern Warwickshire is capped by a thin layer of sedimentary ironstone, known locally as the Hornton Stone. This was quarried on the ridge until quite recently, as a source of ornamental stone, building stone, and aggregate. Many fossils were found in the quarries and represent the remains of Jurassic sea life; roughly 190 million years old.
The fossils included abundant fossil brachiopods; primitive shellfish that are still found in seas today. Amongst these there were occasional examples of so-called spiriferid brachiopods; a family that was close to extinction by Early Jurassic times.
Amongst the best-known fossil spiriferids are much older examples (400 million years), once found in the slate quarries of Delabole, Cornwall. Quarrymen referred to these fossil shells as ‘Delabole butterflies‘, due to their characteristic shape.
I like to think of the younger Edge Hill examples as ‘Edge Hill butterflies’. The example illustrated here is from the Warwickshire Museum collection and bears more than a passing resemblance to its Cornish predecessors.