Eurypygiformes /jʊərɪˈpɪdʒɪfɔːrmiːz/ is an order formed by the kagus, comprising two species in the family Rhynochetidae endemic to New Caledonia, and the sunbittern (Eurypyga helias) from the tropical regions of the Americas.

According to Jarvis, et al.'s 2014 "Whole-genome analyses resolve early branches in the tree of life of modern birds", the group is distantly related to the Phaethontiformes.

[3] When seen as a gruiform, the kagu is generally considered related to the extinct adzebills from New Zealand and the sunbittern from Central and South America.

For example, Fain & Houde found these to be certainly sister taxa[4] and Furo et al. indicated a close phylogenetic relationship between them by cytotaxonomy; they suggest that their common ancestor was separated by the Gondwana vicariance in South America and New Caledonia, respectively.

[5] They and the mesites did not group with traditional Gruiformes in their study, but instead with their proposed clade Metaves, which also includes the hoatzin, pigeons, Caprimulgiformes, flamingos, tropicbirds, Apodiformes, sandgrouse and grebes.