Friday mystery object #371 answer(ish)

Last week I gave you these two genuine mystery specimens from Katharine Edmonson to get your thoughts on:

Tooth-1_9464

IMG_9315

It was most definitely NOT an easy challenge, and I’m still not sure I know the answer to either, even after looking at every species I can think of that might have similar structures.

These are both clearly teeth, considering the internal details:

One image shows the root area of a full tooth, and one shows a section through a tooth – both of which provide really useful information. For example, the full tooth has a central dentine growth that you often find in animals that deal with a lot of strain on the tooth or where infection has got in (I’ve shown this before in elephant ivory).

The sectioned tooth shows a zone of dentine in the middle that suggests some hard use. Notably, that zone matches the shape of the cross section, so those grooves in the sides of the tooth aren’t from wear – they must be intrinsic to the tooth shape.

Generally, tusk cross sectional shape reflects the shape of the socket (until it gets worn down) – so that gives a pretty good way of narrowing down possible options. For example, I’d discount walrus, since they have an almost rectangular section. Warthog tusks have a section somewhere between the number 8 and a mushroom in shape, and Hippopotamuses have a triangular section to their canines, but their incisors are quite circular in section.

Warthog tusk socket

Warthog tusk socket

Then there are wear facets, that can give teeth and tusks a characteristic shape. Hippo canines grow in a corkscrew if unworn, but by rubbing against each other they remain sharp and fresh (like rodent teeth).

This means that teeth and tusks can look weird if the normal wear is disrupted, either by not happening or by happening too much.

There are also unexpected tusks that need to be considered, like the Indian Rhinoceros or dugongs that have hidden tusks.

Of course, some animals have really weird tusks, especially when they’re young or if they’ve experience something that leaves the tusks deformed or altered – which can make identification really hard.

There were a lot of suggestions of Sperm Whale tooth, which is a possibility, but I’ve not seen any that really come close. It may be that both of these are tusks from something more unusual, like beaked whales, but I have looked at a lot of examples of beaked whale teeth and I can’t find any examples that match either of these.

On balance, I think that the first of the tusks may be a Hippopotamus incisor that’s been misaligned with another tooth, causing excessive wear and horizontal stress lines to appear during tooth growth – this is rampant speculation I hasten to add. The second looks a lot more like a Warthog tusk in section than anything else, although the end is more spade-like than I’d expect.

So, after a lot of consideration I’m still uncertain of the identification of either of these, and I would be delighted to hear if you have any more thoughts!

Friday mystery object #371

This week I have a couple of guest mystery objects for you to have a go at identifying. Here’s the first:

Tooth-1_9464Tooth-3_9467Tooth-4_9467

And this is the second mystery object:

IMG_9315IMG_9314IMG_9316

These photos are from Katharine Edmonson and they’re real mysteries, so no need for cryptic clues or hints – let’s see if we can work out what these are using our collective knowledge. Should be fun!

Friday mystery object #226 answer

Last week I gave you this rough and ready mystery object to identify:

mystery226

I thought it might be a bit of a challenge as it had originally been misidentified as a piece of elephant tusk by someone in the museum, many years ago, so it was obviously not a straight-forward identification.

mystery226-label

 

One of the key identifying characteristics of ivory are the Schreger lines, as pointed out by Carlos and rachel. These lines are an optical effect caused by light interacting with the dentinal tubules that provide the structure of the tusk:

Schreger_lines

Tusk section showing Schreger lines

However, these lines aren’t always visible and it will depend on the angle of the cut of the tusk and the angle and intensity of the light.

Another factor to keep in mind is the nature of the material. If you look at a cut section of elephant tusk you note that you get clean edges, because the tusk is quite hard and keeps its structure when cut. It can also show faint growth rings, radiating from the pulp cavity (nearer the tip the cavity is filled in):

elephant_tusk_section

Section of elephant tusk showing clean edges

Instead, the mystery object has a very rounded edge and no clear structure. This suggests to me that it’s horn that has been treated with heat to mould it into shape (keratin that makes horn and hair has thermoplastic properties, which is why hair straighteners work).

So what this mystery object appears to be is a piece of bovine horn – probably cow – that has been melted and shaped at one end to form a cup. The superficial similarity to elephant tusk may or may not have been accidental, after all, elephant ivory is a much sought after material.