Melanerpes aurifrons (Wagler 1829) is the extant golden-fronted woodpecker. Tongue bones extend over the back of the skull to over the nares. The skull is more robust than in related forms, a trait that makes wood pecking possible. Woodpeckers are related to nuthatches in the LRT and both arise from grackles, crows and jays.

Skull and skeleton images from Digimorph.org and used with permission.

Sitta europea (Linneaus 1758; in vivo image; 14 cm length) is the extant Eurasian nuthatch. This wren-sized insectivore is commonly found on tree trunks, sometimes inverted. They live in tree holes, usually made by their sisters the woodpeckers.

Sitta carolinensis (skull image) is the white-breasted nuthatch (14 cm length).

Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.

Wagner JG 1829. Beyträge und Bemerkungen zu dem ersten Band seins Systema Avium (Fortsetzung 1, III). Isis von Oken 22: 645–664, 736–762.

Golden-fronted_woodpecker
wiki/Eurasian_nuthatch