Hello, I found this piece of bone (skull?) in a forest in the south west of Western Australia and I am out of ideas as to what it is.

I'm not sure if it is a skull, pelvis, vertibrae or other but I was working on the hypothesis that it is a skull.

If it is a skull;

The orbits seem to be on the very top of the head, which seems odd.

The bony flaps on the side of the head seem to be ears, which would be strange.

The spine seems to enter on the upperside of the "head" which makes me think it might be a pelvis instead of a skull.

Finally, the "horns". I cannot find any images on the web which have horns like this other than a giraffe (which it is definitely not)

and the thing seems to not have a jaw....at all, so that says it might not be a skull at all.

it is quite small, perhaps the size of a chihuahha skull or some other small dog, and is very light in weight.

Post's pictures

compilation.jpg, 704.27 kb, 1000 x 1000

It's definitely the back half of a mammalian skull. The two bulbous swellings you can see at the top of the upper right image, between the "horns", are the condyles that form the joint between the skull and the first vertebra. Next to them is the foramen magnum (literally, in Latin, the "big hole") through which the spinal cord would enter the skull. You can also see the roots of the zygomatic arches, curving forward, that form the boundary of the temporal fenestrae (equivalent to the human "temples"). The front part of the skull, including the snout and upper jaw, is broken away.

The two photos on the left side of your composite image actually show the underside of the skull, so the "horns" project down rather than up. My guess is that they're very large styloid processes, protrusions from the lower surface of the skull for muscle and ligament attachment. In humans (and presumably other mammals), the styloid processes can be pathologically enlarged, and that might be what we're seeing in your specimen. The other possibility is that the skull might be from a species in which the styloid processes are just very big, although I don't know what species that might be (I'm no expert on mammalian skull anatomy). Or perhaps I'm wrong, and they're not styloid processes at all. My colleagues on this site may be able to help further.

In any case, congratulations on an interesting discovery!

G'day Bryce,

It's hard to be sure from this fragment, but this looks to me like the basicranium of a member of the Diprotodonta - they have exceptionally long styloid processes and they are an Australian group.

From your indication of size and the shape of the basicranial region I think the best fit would be the Swamp Wallaby Wallabia bicolor. I could be wrong as it's hard to make a certain identification from photos of a fragmentary specimen, but that would be my best estimate.

Really? I have a wallaby skull, and it looks nothing like this specimen. Here are some photos:
http://svpow.com/2010/07/02/things-to-m … ll-update/

Many of the kangaroo and wallaby skulls on the following page, including the swamp wallaby, do have very large styloid processes similar to the ones in Bryce's specimen.

http://museumvictoria.com.au/bioinforma … umbmar.htm

Bryce, comparing your skull carefully to the images might help you work out whether it is indeed a swamp wallaby.

Paolo, any idea what the huge styloid processes in these critters are actually for? They're remarkable structures.

Also, I didn't know there were any wallabies that actually had Wallabia as a genus name. That's rather charming.

It's a good question Corwin.

My assumption is that the process (I think it's actually the paramastoid process rather than the styloid, given the position) plays a role in stabilising the head during sustained jumping, which may be why they are more pronounced in some species than others (they seem bigger in the more active jumpers like Red Kangaroos http://museumvictoria.com.au/bioinforma … fuside.htm than in species like the Brush-tailed Rock-wallaby http://museumvictoria.com.au/bioinforma … clside.htm that uses jumping to manouver around a rocky environment).

This is speculation on my part, but you see a similar process in pigs, presumably relating to need to stabilise the head against the forces generated during their rooting action.