Rhinoderma darwinii and R. rufum are two freaky frog species that Charles Darwin discovered while tromping around Chile and Argentina in the 1830s. Unfortunately, it’s looking like the latter is gone for good, thanks to invasive species and deforestation. Scientific American reports:

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The weird and unusual Chile Darwin’s frog (Rhinoderma rufum), whose tadpoles grew inside the vocal sacs of adult males, appears to be extinct: a four-year quest failed to turn up any evidence that the species still exists. The frogs were last seen in 1980.

That’s right: The frogs are “mouth-brooding” — the only genus to do that. So the next time you marvel at the wackiness of human childbirth, just be glad babies chose a hole to grow in other than the one used for karaoke and cheese fries.

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Researchers recently scoured more than 200 sites in Chile and Argentina in hopes of finding R. darwinii or R. rufum frogs. Although they never found any of the latter, they caught 648 of the R. darwinii frogs, including “120 brooding males, 111 non-brooding males, 218 females, and 199 juveniles.” Let’s hope the brooding males aren’t too angsty to get down with the females, and more importantly, that they look something like this:

Oh, Sherlock.

Hope isn’t entirely lost:

Although most of the frog’s historic range has either been destroyed or thoroughly searched, the species could still exist in some forgotten corner of northern Chile, the scientists say.

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