Monogamy in treefrogs & humans

Monogamy in humans, hominoids and tree frogs
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Air sac in a puddle frog species used for visual gesture more than vocalization, probably due to a 'tuned-in' aural predator abundance similar to Hawaiian crickets which lost their song due to predation:
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Some frogs lack vocal sacs, such as those from the genera Heleioporus and Neobatrachus, but these species can still produce a loud call. Their buccal cavity is enlarged and dome-shaped, acting as a resonance chamber that amplifies their call. The noise of flowing water overpowers any call, so some river frogs communicate by other means.

The main reason for calling is to allow males to attract a mate. Males call either individually or in a group called a chorus. Females of many frog species, for example Polypedates leucomystax, produce calls reciprocal to the males', which act as the catalyst for the enhancement of reproductive activity in a breeding colony.[39] A male frog emits a release call when mounted by another male. Tropical species also have a rain call that they make on the basis of humidity cues prior to a rain shower. Many species also have a territorial call that is used to chase away other males. All of these calls are emitted with the mouth of the frog closed.

A distress call, emitted by some frogs when they are in danger, is produced with the mouth open, resulting in a higher-pitched call. The effectiveness of the call is unknown; however, it is suspected the call intrigues the predator until another animal is attracted, distracting them enough for its escape.

Many species of frog have deep calls, or croaks. The English onomatopoeic spelling is "ribbit". wikipedia

Nature by number: spatial geometry in natural growth patterns

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New apith skeletons found
http://www.pnas.org/content/113/51/14769.short