Rhea americana (extant) is the largest rhea of South America. The juvenile has a large thumb claw and unfused fingers that fuse with maturity. Essentially this is a giant tinamou.
Casuarius casuarius (Brisson 1760; up to 2m tall) The extant cassowary is one of the few birds with a bony crest or casque on its head. Derived from a tinamou like Rhynchotus, this flightless omnivore feeds mainly on fruit, shoots and small seeds. The crest shape variws with the individual. Females are larger and more brightly colored. The manus is a fused (undifferentiated) vestige.
Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.