#bathornithidae

https://extinctworld.in.ua/paracrax/

It was originally mistaken for a long-legged vulture (under the name Neocathartes) when first discovered in the 1940s, but later studies have shown it was actually one of the smaller members of the bathornithids -- close cousins of the more well-known South American “terror birds”, successfully occupying terrestrial predator niches alongside large carnivorous mammals.

That said, nothing is ever absolute in science, and taxonomy is constantly being reinterpreted and updated. So of course these birds could still turn out to be something else, such as bathornithids or an entirely new clade of large flightless Cariamiforme which were convergently similar to phorusrhacids. If more fossil material is found, or if somebody does further analysis and comparison of the existing specimens and comes to that sort of conclusion, then we’ll just have to revise their classification accordingly.