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Todmorden Moor Shark Fossils

Sandy Road Colliery spoil heap, beside the Flower Scar Road, is a good fossil-hunting area for both marine and plant material.

A member of the Lancashire group of the Geologists' Association, Peter del Strother, picked up a mudstone concretion during a geological walk in 2013 and realised that it contained animal material, in this case a collection of hollow spines and denticles, or teeth, from a Carboniferous shark.

Research on the concretion has been carried out by David Marshal at Portsmouth University and the findings were published recently. The remains were examined in thin section, and some denticles were dissolved out of the carbonate matrix and examined under a scanning electron microscope. The remains proved to be from a new genus of small shark which has been named Acanthorhachis.

The rocks of Todmorden Moor are Upper Carboniferous in age and are about 310 million years old. At the time northern England was part of a delta covered by rain forest, and cut by meandering river channels.

England was located just north of the equator at that time in the tropical wet belt. Sometimes sea levels rose so that water covered the marshes and swamps of the rain forest, bringing in marine shells which then became fossilised in layers of mud. The body of the shark would have been washed into a quiet area of still water and decomposed slowly. Its body remains are in perfect condition as the tiny tips of the denticles are completely unbroken.


What is special about this fossil is that it represents a death assemblage from a single fish. It is clear there is a wide variety of denticle morphology from one animal. If the denticles had been found separately it would have been tempting to ascribe them to different animals and species.

This is an exciting find and the results have been published recently.
Acanthorhachis, a new genus of shark from the Carboniferous (Westphalian) of Yorkshire, England 2013. David M Martill, Peter J A Del Strother, and Florence Gallien. Geol. mag: page 1 of 17 Cambridge University Press 2013

This information is provided for us with thanks to Alison Tymon and Peter del Strother of West Yorkshire Geology Trust.