Gruesome, bizarre mountain lion deformity found during legal hunt

The deformed mountain lion seems to have teeth growing out of its forehead. (Idaho Department of Fish and Game via AP)

You may have seen the above image trending on your social media website of choice: A female mountain lion, killed during a legal hunt in Idaho after attacking a dog, sprouting what appears to be an extra set of teeth out of the top of her head.

Some outlets are reporting that the phenomenon is "puzzling" to biologists – but that's a bit misleading. The only thing that makes this case truly puzzling is that no biologist has been able to examine the carcass directly. With only photos to go on, scientists are really just shooting in the dark. But no one is suggesting that the mountain lion in question has some kind of hitherto unknown ailment.

Based on the photo alone, experts have speculated that the teeth and whiskers might be the result of either a parasitic twin or a rare tumor called a teratoma. Parasitic twins can form when an embryo absorbs part or all of a would-be twin during development. Teratomas can appear quite similar, containing hair, teeth, and even more complicated bodily tissues, but they form when some of an embryo's own cells get tucked into the wrong place. Many human cases that get labeled as "parasitic twins" by distressed patients and the media are probably just mature, grotesque teratoma tumors.

Writing for Earth Touch News, Sarah Keartes points out that teratomas, while rare, are considered much more common than true parasitic twins. So without anything but photos to speculate over, it would make more sense to blame a tumor than an evil twin.

"The hunter is not required to turn the animal over to Fish and Game for further analysis," the IDFG said in a statement. But representatives have expressed hope that the hunter will come forward and turn the animal over for analysis.

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