Amazing Cretaceous Bony Fish Preserved in Flint
For a local Kent resident the habit of picking up unusual objects to place in his rockery at home has enabled scientists to get to grips with a rare example of a fossilised Cretaceous fish.
The stone shaped fish head was spotted by Peter Parvin and his wife whilst they beach-combed on a caravan holiday to Pevensey in East Sussex in 1993. Found amongst the pebbles as the tide was going out, Mr Parvin thought nothing of his find, simply placing it amongst the other curiosities he had collected in this rockery. However, a chance conversation with a volunteer from Maidstone museum in a pub, led to him bringing this rare, ancient relic to the museum for closer examination.
The fish head fossil measures approximately 15 cm across, it is shown in the photograph facing to the right of the screen. The eye, mouth and shape of the gills can clearly be seen.
“I have never seen one of these before”, commented Dr Ed Jarzembowski, the Keeper of Natural History at Maidstone Museum. “Quite simply it’s priceless”.
In contrast with most fossils found from this period (which are associated with chalk), the fish head has been preserved in flint, this makes it particularly rare and valuable. The hard flint would have helped maintain the quality of preservation, even as this stone was bumped and bashed on the shoreline of Pevensey beach.
The fish has been dated to around 80 million years ago (Late Cretaceous) and is a representative of the modern bony fish group the Teleosts. This type of fish, with its streamlined fins, highly manoeuvrable body and ability to open its jaws wider than other more primitive fish forms evolved from the Acanthodian fishes. Bony fish dominate the world’s freshwater and oceans with a greater diversity of animals at the taxonomic level of Family than any other group of vertebrates.
During the Late Cretaceous, most of the UK was covered with a warm, shallow tropical sea. These seas swarmed with life and there are a number of common fossils associated with flint nodules. Sponges are often found in association with flint nodules. Flint occurs as extremely hard nodes in chalk deposits. It is formed by chemical reactions within the chalk sediments and it is composed of silica in the form of microscopic quartz crystals. The silica came mainly from the exoskeletons of dead sea sponges (these are made of silica), and they were subject to dissolving into solution under the alkaline environment of the chalk deposits. The silica tended to re-solidify if it encountered local acidic conditions such as the acidic conditions surrounding decaying organic material such as this fish head. This may help to explain how this fish head fossil was formed.
There are plans to put the fish head on display at the local museum, although it may be ultimately sold in order to help raise funds for the museum’s development.