Friday mystery object #1 answer

The mystery object I showed you on Friday was this:

and I was looking for an identification of what it is and why does it look like that.

Carmenego came closest, identifying that it was ivory, but she just missed out on what caused the marks. The shape of the marks is a bit of a give-away for a natural history geek like me, they are caused by a rodent gnawing. However, the type of rodent threw me when I found this label:

Piece of gnawed ivory label

Now, I had expected the gnawer to be a porcupine as they commonly gnaw bone and have been recognised as sources of Pleistocene cave fill material, since they drag bits of carcass back to their lair. I had never heard of Sciurus eborivorous, so I did a bit of research. It turns out that the binomial name is now Protoxerus stangeri eborivorus (Waterhouse, 1842) and the common names are ‘Stanger’s Squirrel’ or the ‘Forest Giant Squirrel’. Further research into the Waanzi name mboco (‘mbukeu’) provided yet another name and this wonderful description:

…Geocichla compsonoia — and a very remarkable animal of the squirrel kind, called by the natives the mboco, and which eats ivory. I have called it the “ivory-eater,” as the fact that it hunts in the woods the carcasses of elephants and gnaws the ivory, often destroying the finest tusks, can not be disputed.

Du Chaillu, P.B. 1861. Explorations and adventures in equatorial Africa. New York, Harper & brothers

Beyond this there is relatively little information available. This rodent is large and arboreal, similar in appearance to other squirrels, with a thinner tail than the grey and red squirrels that we have in the UK. They are of Least Concern according to the IUCN. The only illustration I could find was this drawing by Clifford Lees from the Squirrel Species of the World site:

: Stanger’s squirrel

The final thought I should add is that the range of these squirrels does not now include South Africa, where this tusk originated. Either the species of gnawer was misidentified, the location of the ivory source was mistaken or the range of these squirrels has contracted.

Another mystery object on Friday – perhaps a slightly easier one…