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Archaeology is often confused with palaeontology – with most archaeologists having been asked at least once in their career about the most interesting fossil they have found. Now archaeologists from Colchester Archaeological Trust (CAT), at least, can provide an answer to that question. During excavations at the former Essex County Hospital on Lexden Road in Colchester (which also revealed the lead coffin that featured in CA 437 and CA 438), the team uncovered the fossil of an ichthyosaur vertebra in a Roman context.
The fossil was found in a rectangular-shaped, steep-sided pit within which were 68 sherds of Roman pottery, 18 fragments of Roman ceramic building material, butchered mammal bones (predominantly from cattle, pig, and goat/sheep, but possibly including horse and cat remains), a fragment of Purbeck marble veneer, an iron nail, a complete copper-alloy toilet spoon (or ligula), and the centrum (or round centre part) of an ichthyosaur vertebra. The types of pottery present suggest that these items were deposited in the third quarter of the 2nd century AD.
The fossil was not immediately recognised on excavation but was identified by CAT archaeologist Chelsea Hodges during post-excavation analysis. The centrum was subsequently assessed, revealing a thin patch of green micaceous sandy siltstone. A similar lithology can be found in four formations: the Atherfield Clay Formation, the Hythe Formation, the Sandgate Formation, and the Folkestone Formation, all of which make up the Lower Greensand Group in the Weald Basin in Kent. During the Roman period, East Wear Bay in Folkestone was the location of a significant Greensand stone-quarry that was active until at least the 4th century AD. Notably, the bay has also yielded lots of fossils, possibly hinting at the Colchester fossil’s origins.
This is not the first ancient marine fossil to be discovered in a Roman context. Excavations at King’s Hedges on the outskirts of Cambridge revealed the vertebrae of a plesiosaur (see CA 405), which was found in a pit containing heaps of Roman pottery. It and the Colchester ichthyosaur are the first large vertebrae fossils to be found in Roman deposits in the north-western provinces of the Roman Empire and, interestingly, both were discovered in East Anglia.
The reason that each example was collected and eventually deposited is unknown but, as the authors of the recent paper published in Britannia (https://doi.org/10.1017/S0068113X26100749) hypothesise, they may have been curated and displayed as curiosities, or perceived as sacred relics that confirmed the existence of mythical beasts.
Text: Kathryn Krakowka / Image: Colchester Archaeology Trust
