Mounting the type specimen of Pliosaurus carpenteri Benson et al., 2013, an 8m-long fossil pliosaur skeleton, including the 3D-printed 1.8m-long replica of the skull for Bristol Museum & Art Gallery

The type specimen of Pliosaurus carpenteri Benson et al., 2013 from Westbury in Wiltshire, UK, is the most complete skeleton known of this extinct species, with an estimated body length of 8m. The skeleton was mounted for a temporary display at Bristol Museum & Art Gallery in 2017 for the first time since it was excavated in 1994. The fossilised skull is 1.8 m long, very heavy and consists of many very fragile pieces. Mounting the real skull in position would have required a large amount of unsightly supporting metalwork that also would have obscured some very interesting pathology on the palate inside the mouth. One option was to CT scan the individual pieces of the skull and use the subsequent digital models to 3D-print replicas. This method of making a lighter replica skull would present less risk to the specimen than traditional moulding and casting and would be quicker, cheaper and safer for the duration of the exhibition. Importantly, the process would also provide detailed 3D morphological data of the skull’s internal anatomy for the first time, which would be invaluable to ongoing research. The pieces of the 3D-printed skull were mounted with internal steel armature and painted to match the real specimen. However, there are many ethical and practical issues to consider when replacing missing bones with replicas, including: making clear to the public what is real and what is not; and using appropriately stable and tested materials where possible.