The Gruiformes (/ˈɡruːɪfɔːrmiːz/ GROO-ih-for-meez)[citation needed] are an order containing a considerable number of living and extinct bird families, with a widespread geographical diversity.

Rails (Rallidae), flufftails (Sarothruridae), finfoots and sungrebe (Heliornithidae), adzebills (Aptornithidae), trumpeters (Psophiidae), limpkin (Aramidae), and cranes (Gruidae) compose the suborder Grues and are termed "core-Gruiformes".

The families of mesites or roatelos (Mesitornithidae), button-quails (Turnicidae), Australian plains-wanderer (Pedionomidae), seriemas (Cariamidae), and bustards (Otididae) each represent distinct and unrelated lineages.

Over the decades, many ornithologists suggested that members of the order were in fact more closely related to other groups (reviewed by Olson 1985, Sibley and Ahlquist 1990).

However, it was not until the work of Paton et al. (2004) and Fain and Houde (2004, 2006) that the correct placement of buttonquails within the shorebirds (order Charadriiformes) was documented on the basis of phylogenetic analysis of multiple genetic loci.

Using 12S ribosomal DNA sequences, Houde et al. (1997) were the first to present molecular genetic evidence of gruiform polyphyly, although apparently they were not convinced by it.

One locus, i.e., mitochondrial DNA, contradicts the strict monophyly of Coronaves (Morgan-Richards et al. 2008), but phylogeny reconstruction based on mitochondrial DNA is complicated by the fact that few families have been studied, the sequences are heavily saturated (with back mutations) at deep levels of divergence, and they are plagued by strong base composition bias.