Comparing the surviving fossil mammal specimens collected by Charles Darwin during the Voyage of the Beagle with original drawings and casts of the specimens from 1837-1840, it is clear that some have sustained significant damage in the 185 years since they were collected.
Digitising the collection and releasing 3D models and specimen data online will go a long way to reducing handling of the specimens. This will reduce risk of further damage, whilst still making them accessible to researchers and the public; however, it is not the only tool we have.
Conserving the specimens for future generations involves providing stable storage conditions (particularly for changes in humidity and temperature), and using appropriate conservation grade materials and established techniques to ensure their preservation.
Heidi Potter is one of our long-term volunteers in the Earth Sciences Department at the Museum. With guidance from the Museum conservation team, Heidi has become an expert on creating hand-made conservation-grade storage supports and enclosures for fossil mammal specimens and we have used her expertise on this project to re-store the Toxodon specimens in our collection.
Using a template as guide, Heidi creates individual boxes for each specimen using acid-free card. She then creates bespoke inserts using Plastazote® foam to fit around the specimens so they do not move in the box whilst the specimens are moved in and out of their storage cupboard. She designs the inserts to show as much of the specimen as possible, whilst keeping it secure. This helps reduce the need for handling the specimens.
Although these boxes are sufficient for most specimens, the larger and heavier specimens require support using more rigid materials which spread and support the weight of the specimens more evenly. For these specimens, the Museum conservation team construct Epopast supports. These supports are made from epoxy resin and provide a strong, rigid support, which can be lined with Plastazote.® In the next stage of this project we will need to take this approach for the Toxodon skull and other large specimens in this collection.
Darwin’s Fossil Mammals on display
Some of the specimens that have been scanned as part of this project are currently on display in Hintze Hall. These specimens needed to be taken off of display to digitise them. This was a good opportunity to check over the specimens to make sure they were still in a good condition.
Looking to the future, we hope to secure funding for the next stage of the Darwin Fossil Mammals digitisation project. This will enable us to digitise the remaining fossil mammals collected by Darwin, but also to fully assess the specimens from a conservation perspective and to make bespoke epopast supports for a selection of them (including the type skull).. An aspiration for this collection would be to precisely document everything that has happened to the specimens from their point of collection to the present day including what was used to repair the specimens at various points in their history and the impact these repairs have had. CT scanning of selected specimens (which will show up hidden structures such as pins inserted into bone to stabilise them) and superimposing them on scans of casts and drawings of the same specimens may help untangle this history. This would enable us to make fully informed decisions about future management of the specimens.
For more information about the digitisation of Darwin’s Fossils please visit www.nhm.ac.uk/darwinsfossils. To find out how these discoveries sparked Darwin’s theory of evolution please read our latest blog post.
We want to hear from you!
If you are using these 3D models
or have ideas about what you might like to hear about from this project, we would love to hear your thoughts. Get in touch and stay up to date with this project by following @NHM_Digitse, @NHMFossilMammal and @NHM_IAC on Twitter.