Short answers, pulled from the story.
Max Fürbringer established the order Gruiformes on the 15th of May 1888. This event marked a turning point in ornithology when the German comparative anatomist grouped together a chaotic collection of wading and terrestrial birds. The classification was a pragmatic solution to a taxonomic crisis at that time.
The core Gruiformes include rails, flufftails, finfoots, sungrebe, adzebills, trumpeters, limpkins, and cranes. These groups are united under the suborder Grues and share skeletal and genetic markers that distinguish them from other former members. They are the only true Gruiformes according to modern genetic analysis.
The traditional order Gruiformes was reclassified because it lacked distinctive apomorphies or shared derived characteristics that would prove a common ancestry. Modern genetic analysis revealed that the order was a polyphyletic mess of unrelated species forced into a single box out of necessity. Scientists now recognize that the birds were not related at all despite the broad definition used for over a century.
The kagu and the sunbittern are each other's closest relatives yet they share no common ancestor with the true Gruiformes. DNA evidence has shown that these birds belong to a completely different lineage known as the suborder Eurypygae. The kagu is a flightless bird native to New Caledonia while the sunbittern is found in the tropical forests of Central and South America.
Molecular genetics revolutionized the classification of the Gruiformes by allowing scientists to analyze DNA sequences and reveal true evolutionary relationships. Studies by Houde et al. in 1997 and subsequent research by Fain and Houde in 2004 and 2006 demonstrated that the traditionally recognized order consists of five to seven unrelated clades. This genetic revolution forced ornithologists to abandon the traditional order and reclassify its members into new groups.
The limpkin is the only living member of the family Aramidae and is known for its diet of apple snails which it extracts using its long curved bill. The trumpeters live in the dense forests of South America and are large ground-dwelling birds known for their complex vocalizations and social behavior. These unique adaptations reflect the evolutionary history of the surviving members of the Gruiformes.