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Tetrapod Zoology

Tetrapod Zoology

Amphibians, reptiles, birds and mammals - living and extinct

"San Diego Demonoid": you mean that dead opossum?

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By night, I work as a technical research scientist, writer of papers and so on, but by day I walk the beaches of the world, looking for partially decomposed mystery carcasses and identifying them. Kidding: of course I don’t, but you get the idea – thanks in no small part to the Montauk Monster flap of 2008, I’ve become known as the guy who identifies weird carcasses. In fact, so many queries of this sort come in via email that I don’t have time to blog about them anymore.

On the 1st of February I was emailed by the people at vice.com about a weird mammal carcass they’re calling the “San Diego Demonoid”. Loren Coleman (at Cryptomundo) has since referred to it as the “San Diego Diablo”. I suggest we call it “a dead opossum”, because that’s what it is and it’s nothing special. At least two photos were taken by Dylan Dessureault, the discoverer of the carcass. I looked at the photos and was mightily unimpressed by the dead Virginia opossum Didelphis virginiana I could see staring back at me. I passed this identification on to my friends in the sceptic community, and indeed Sharon Hill at Doubtful Newsblog and Ben Radford at DiscoveryNews have both covered the opossum identification of the carcass already.

As usual, there are some silly ideas out there: that it might be a dog, raccoon, tapir (!!!), or an escaped mutant from a lab (of course). The term Chupacabra has been used a lot, since it now seems to be a word that people associate with any ugly, long-snouted mammal that has pointed canines. And a popular idea this time round is that it might be a fake or work of art, perhaps composited from the remains of other animals.

I don’t want to be seen to be giving publicity to yet another of those waste-of-time, publicity-seeking “monster carcass” stories, but at the same time I feel it’s worth helping to spread an evidence-based identification of this carcass, since its true identity is so frikkin’ obvious.

Why is the identification “obvious”? The carcass is a mammal with a long, rat-like snout, a rather high number of small incisors, closely spaced premolars with pointed cusps, and especially long, curved upper canines. We can guess from the sand and seaweed (and from Castoro’s shadow and shoe-print in one of the photos) that it’s mid-sized – not tiny, not huge, but something like 60 cm long. Note that, unlike dogs, foxes and so on, it doesn’t have an obvious rhinarium (the area of dark, distinctly textured skin that surrounds the nostrils in such animals). These features all immediately screamed “opossum” to me. Partly this is because I’ve handled opossum skulls and am familiar with their surprisingly big upper canines and high number of incisors (there are five uppers and four lowers for each side) [opossum skull here borrowed from Cryptomundo]. Even the fur looks opossum-like (mammal carcasses typically slough fur after they’ve been decomposing in water for a while, and this explains the naked face). When you add all this to the fact that the Virginia opossum is a common, widespread mammal in California, we have an obvious and uncontroversial identification.

Incidentally, the Virginia opossum isn’t native to California. It was introduced there in about 1910 from Tennessee and swiftly became extremely abundant. There have been numerous other opossum introduction events across the west as well.

For previous Tet Zoo articles on the identification of carcasses, see...

The views expressed are those of the author and are not necessarily those of Scientific American.

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