Humble flint sea urchins and the stories they tell

Joe Shimmin (UK) Flint is a very hard-wearing rock from the chalk of the Upper Cretaceous. Whole beaches made of flint pebbles can be found many miles away from the chalk strata that the nodules originated in, owing to the rock’s ability to withstand the processes that destroy other rocks quickly. Flint sea urchins are especially hard-wearing, as their rounded shapes require a lot of force to damage, while less-rounded flints tend to break up over time if subjected to high-energy environments, such as beaches and fast-flowing rivers. Because of this robustness, it is possible to find flint urchins, which have undergone some very interesting journeys before being collected, adding to their interest for fossil hunters. Fig. 1. The hardness of flint and the rounded shape of flint urchins make them extremely robust fossils. All flints start off within chalk strata. Where these strata are exposed at the coast or in quarries and cuttings, it is possible to collect flint sea urchins, which, at first, look very much as if they are preserved like every other urchin found in chalk. They have a white calcite-replaced test and all that can be seen of the flint within is a slight blueish tint or maybe a glimpse of the nodule through the anal or oral apertures. Of course, flints can also be found that partially or fully envelop an urchin and, in these cases, highly aesthetic display pieces can sometimes occur. Fig. 2. Two of these pristine fossil urchins, extracted straight from … Read More

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Fossil sea urchins from the Middle Eocene of the Bartonian of Christchurch Bay, UK

David N Lewis (UK) The spectacular fossil gastropods and the teeth of sharks – found at the type locality of the Middle Eocene Bartonian in Christchurch Bay (Hampshire and Dorset) – overshadow the other fauna and flora found there. However, among the ‘Cinderella’ groups are the echinoids (sea urchins). Several kinds, both ‘irregular’ and ‘regular’, can be found, some preserved with superb detail. Fig. 1. Sketch maps to show the location of Barton-on-Sea (modified after Lewis & Donovan, 2008).The coastal holiday resorts of Christchurch Bay, near the New Forest, include Highcliffe to the west, Milford-on-Sea to the east, and the well-known Barton Cliffs of Barton-on-Sea between the two (Fig. 1). All lie within the Hampshire Basin of southern England. This coastal stretch is famous for its extensive range of well-preserved Eocene fossils found in the sea cliffs and on the foreshore. The most fossiliferous area is sometimes referred to simply as ‘Barton’, and the clays and sands in which the fossils are found as the ‘Barton Beds’. Of particular interest to fossil collectors, students and holiday-makers alike are the abundant fossil molluscs and the teeth of sharks. However, there are other fossils too, including plants, microfossils, a wide variety of other invertebrates such as bryozoans, brachiopods, corals, crabs, echinoderms (brittle-stars, starfish and sea urchins) and worms, and vertebrates including fishes, reptiles and rare mammals (see Hooker, 1986). Trace fossils can also be seen in the clay sequences. In fact, some of the clays allow considerable fine detail of the fossils … Read More

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