Tinamou - Taxonomy and Phylogeny

Taxonomy and Phylogeny

The family Tinamidae consists of about 47 species in 9 genera. They range in size from the Dwarf Tinamou at 15 cm (6 in) and 42 grams (1.5 oz) to the Gray Tinamou at 48 cm (17 in) and 1.6 kg (3.7 lbs). Although they look similar to other ground-dwelling birds like quail and grouse, the characters they share are the result of convergence and plesiomorphy rather than shared evolutionary innovations. Tinamids have no closer living relatives than the flightless ratites, and thus are placed in their own order, Tinamiformes. Their taxonomic names are based on the Galibi word for these birds, tinamu.

"Tinamidae" was defined as by Gauthier and de Queiroz (2001): "Tinamidae refers to the crown clade stemming from the most recent common ancestor of Tetrao major Gmelin 1789 and all extant birds sharing a more recent ancestor with that species than with Struthio camelus Linnaeus 1758 and Vultur gryphus Linnaeus 1758."

Of Gondwanan origin, tinamids are related to the ratites. Although the fossil record in South America is generally poor, the known tinamiform fossil record goes back 10 million years to the Miocene epoch. Together with the ratites, they make up Palaeognathae ("old jaws"), while all other living birds are members of Neognathae ("new jaws"). Unlike other palaeognaths, tinamids do have a keeled sternum, but like the other palaeognaths they have a distinctive palate.

Recent phylogenomic studies have shown tinamids as the sister group to Australasian and Oceanian ratites (i.e., cassowaries, emus, and kiwi), with South American rheas and African ostriches as successive outgroups. Tinamids themselves were shown to be monophyletic.

Research published in 2010 found that one of the closest ratite cousins of Tinamou was the moa from New Zealand and that the moa was more distantly related to the emu and cassowary than had been thought previously. See the entry for the moa.

Tinamous are divided into two subfamilies, Nothurinae, the aridland tinamous, and Tinaminae, forest tinamous.