Tuatara skull preparation

When museum staff prepare a skeleton for study or display, they usually macerate it   soak it in water until the flesh rots off the bone. This produces nice, clean, separated bones, but with small reptiles such as tuatara you end up with no skull. The pieces that make up the skull fall apart when the ligaments holding them together rot away. What’s left is a jigsaw puzzle of small oddly shaped bones that only an expert with a lot of patience could put together. To solve this problem, Raymond Coory, Te Papa’s reptile collection manager, had to enlist the aid of some little helpers – a colony of dermestid beetles (scientific name Dermestes maculatus).

Dermestid beetles love dead flesh – a large colony can reduce a mouse to a skeleton overnight. Te Papa has a special supply of these museum assistants, suitably isolated of course, as they are enthusiastic destroyers of all kinds of stored products, from sheepskins to cigars. They could devastate museum collections! And they have been known to bore through wood, fibreboard, plaster moulds – even lead.

The good thing about the dermestids’ flesh eating, though, is that they don’t entirely remove the ligaments between the bones – so the skeleton remains slightly articulated, and with small reptiles the skull remains intact.

However, Raymond didn’t have any freshly dead or frozen tuatara available, only pickled ones that had been stored in alcohol for decades. Definitely not to dermestid beetles’ taste! So he had to soak his pickled tuatara in water for about two weeks, to rid its skin of the alcohol and formalin. Then he cut away as much flesh as possible without damaging the bone. Then he soaked the carcass for several days in something more to the dermestids’ liking – chicken stock.
 

At first the beetles ate vigorously, but they slowed down after a week or two, so Raymond refreshed the remains with chicken stock once more. Things were getting very smelly, but that was no deterrent to the beetles. They soldiered on, but now drought was becoming a problem – the corpse was drying out too much, so Raymond had to spray it regularly with water.

Eventually, after a couple of months, a recognisable tuatara skeleton was revealed – with skull nicely intact. The skeleton then went into the freezer to kill off any remaining beetles. Finally, Raymond took it out, picked off the dried flesh, and put it into the sun to bleach. He also gave it several soakings in Steradent (to whiten it and get it smelling minty-fresh).

Text originally published in Tai Awatea, Te Papa's onfloor multimedia database.