Identify the oddity

Sauropod vertebra!

It's a ropenid hellasaur!

Part of Richards Owlman costume?

Gorgonopsid!
Nah, I'll play it safe and suggest that it is some sort of mammal. May it have the face somehow splayed into two?

Which end is the front?

It's a hitherto unknown species of rhinograde.

Er... it's a mammal, I know that for a FACT.

The skull of some sort of elephant, especially if that's the infraorbital foramen at the bottom left.

Any sirenian?

Trick question... It's a photograph!

Good, good.. very encouraging so far, please keep 'em coming...

Dicynodont.

Is it an Asian elephant?

My guess is that it is the skull of a walrus. That would also explain why you didn't include the lower jaw...or the dentition.

I recently had a similar situation to this question in central Vermont. Local farmers had unearthed a skull that looked much like this, situated it in a similar orientation (viewed from behind) and took pictures. Beluga fossils have been unearthed in the western part of the state (Lake Champlain used to be essentially an inland sea) and they were convinced it was a marine mammal. I was initially leaning toward the idea of a walrus until I realized the correct orientation. Instantly it hit me that they had dug up the braincase (minus the rostrum) of an old draft horse.This, however, is not a horse. Yet I cannot figure out what it is. Hopefully my trip down memory lane will help others guessing.

A Glyptodont

Could it be an elephant seal? Are those 'shallow cavities' where that frumpy nose comes into play?

A mammal skull roof plus zygomatic arches. Elephant sounds good because of the 3D shape of the frontals.

I was thinking that the rugose patches were attachment sites for the elephant equivalents of levator labii superioris muscles. Something important (and large) attaches at those patches. And I suspect that "something" requires extensive sensory innervation from the maxillary division of CN V.

Can't wait to find out what it is!

Hmm...the clusters of foramina at the back of the skull roof are very reminiscent of wombats, but they don't have the very retracted narial opening or such rugose attachments for the levator muscles of the snout. I vote for the modern tapir Tapirus (which would also explain the monstrous infraorbital foramen) - not sure which species, though.

Ignore my statement above. Robin Beck is close in guessing wombat. It is a view from the anterior. The jugal is participating in the jaw articulation making it a marsupial. I'd guess Lasiorhinus.

I'm guessing a species of short-faced kangaroo (Procoptodon? Simosthenurus).

Where do you see a jaw articulation? I can only see the coronoid processes. And the bone behind it ought to be the squamosal... no?

I just see what look to be coronoid processes as well.

If those dorsal foramina are located in the parietal bones (I've taught on Planet Human Anatomy too long to be sure), then I'd say that the animal had lots of emissary veins, perhaps to cool the brain in a hot climate.

Glyptodont, the foramina are for the plate on the skull roof.

I think that Jorge Velez-Juarbe and TJ are right - it's a glyptodont. Pictures I've seen of their skulls have botht the rugosities and the "paired concavities". I think that the photo has been cropped at just the right point to disguise how short-faced the creature is.
Have a look at http://www.skullsunlimited.com/fossil-glyptodont.html or http://gastondesign.com/07galleries/mammalskulls/
for example to see what I mean. I dont know if the links will work, but if they dont copy & paste them in your browser.

Let's see how much I don't know...

No elephant would have coronoid processes sticking up like that. Tapirs have more domed skull roofs. I like glyptodont, because of how short the face must be. It seems a good match for this one.

Excellent mystery photo. Keep 'em coming!

Well, I can easily rule out any type of marine mammal, modern or extinct (i.e. sirenian, desmostylian, walrus, sea lion, seal, etc., and probably the rest of the carnivora as a whole). Also, doesn't really look much like an elephant either - elephants have a large portion of the braincase dorsal to the orbits.

I agree with the glyptodont ID - its one of the only critters I've seen with the extremely narrow, deep terminations of the naris.

Yeah, it does look a lot like the Glyptodon skull on Skulls Unlimited.

Now it's a challenge to narrow down which glyptodont... Glyptodon? Doedicurus? Glyptotherium? Panochthus? Hoplophorus? Palaehoplophorus? Propalaehoplophorus?? Parapropalaehoplophorus???

Ah, it is clear now! Looks like a pretty good match to that skull of Glyptodon clavipes, so I'll say that; Glyptodon clavipes.

I also thought of wombats but the whole shape of the skull roof is wrong, and the rugosities and apparently downturned nasals don't fit either. Presumably the cropping was to hide something that would have made it much easier to identify, but I think the maxillae are definitely fenestrated. So I guess it's a large rodent, probably a porcupine of some sort.

Well I can't deny the glyptodontid argument. Particularly since it looks like there's some sort of projection beneath the infraorbital foramina. I've seen Vombatus skulls and this appeared to be similar, but with a broader snout. Live pictures of Lasiorhinus might appear to match that, but the glyptodontid idea is too perfect. Porcupines (particularly OW porcupines) have a snout that is almost domed. Both New and Old World porcupines would not have such a short face.

I decided it was honourable to first have a try without benefit of Google; but yeah, it's a glyptodont isn't it?

OK, I jump onto the glyptodont bandwagon.

Hey, "Sunday night" -- which Sunday?

I think maybe it is not a skull... Maybe an upside-down pelvis?

Everybody and their mother already beat me to it, but my first thought was "glyptodont" when I saw the photo, too.

My knowledge of glyptodonts is terrible, but wouldn't a fossil animal's skull look a little less...recent??

I was wondering about that myself too. However, there are plenty of examples of extremely well preserved pleistocene skeletons in caves in south america. Additionally, if you look at the specimen in question, there are plenty of cracks, the sort of which you'd expect in a fossil buried in sediment.

I know!!!! It's a skull of some kind!

The cave bear bones I've handled are all so young they still look dead. The official definition of "fossil" is "older than 10,000 years"; I wonder if that shouldn't be changed to 100,000, so that fossils reliably look like fossils.