Evolution and systematics

So similar in appearance are Australasian pseudo babblers and Asian scimitar babblers that both were formerly grouped together in the same tribe of the babbler family, Timaliidae. However, molecular evidence and examination of the skeleton have shown that the similarities are superficial. Pseudo babblers are divergent members of a quite different assemblage of crow-like songbirds that radiated massively within Australia at least 30 million years ago. Like other crow-like birds, pseudo babblers have a single pneumatised depression (fossa) in the head of the humerus. The sternum (breast bone) is shallowly keeled and processes on the pelvic girdle are much attenuated, both signs that pseudo babblers live more on leg than wing. They have other unique skeletal traits in the palate and skull that interact to support the bill when probing and digging.

The five living pomatostomid species belong to two genera. Garritornis contains a single species (G. isidorei, rufous babbler) endemic to the lowland rainforests of New Guinea. Pomatostomus comprises four species. Gray-crowned babblers (Pomatostomus temporalis) and Hall's babblers (P. halli) are centered in the woodlands of Torresian north Australia, and white-browed babblers (P. superciliosus) and chestnut-crowned babblers (P. ruftceps) are centered in similar habitat across southern Australia. The history of their evolution is unclear.

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