Andalgalornis

Andalgalornis is a genus of flightless predatory birds of the extinct family Phorusrhacidae (often called "terror birds") that lived in Argentina. The type and only species is A. steulleti.
"Andalgalornis" is known from an incomplete skeleton and some single bones found from sites in the Entre Ríos and Catamarca Provinces of northeast and northwest Argentina. The fossils were uncovered from the Late Miocene (Huayquerian in the SALMA classification) Ituzaingó Formation of the Paraná Basin.
Description.
"Andalgalornis" stood around one and a half meters tall. The subfamily to which the genus belonged, the Patagornithinae, contained species that were of quite slender build; it looked much like the larger phorusrhacid "Phorusrhacos", but it was more elegant and smaller and had a proportionally higher beak, the most massive in proportion to body size of all phorusrhacids. A recent analysis of CT scans of the skull of "Andalgalornis" suggests that the beak was strong dorsoventrally (in the vertical plane) but relatively weak mediolaterally on either side. The beak's weakness has led some to suggest that the bird could not have taken down large prey, but consumed smaller, more easily manageable prey that could be killed with weak bite forces. However, the beak's dorsoventral strength may have enabled "Andalgalornis" to quickly strike down on or slash its prey in a hunting strategy that involves a series of repeated blows. This is analogous to the feeding behavior of other weak-biting predators such as "Smilodon" or "Allosaurus", which also rely on vertical striking to kill large and dangerous prey.
A study of its neck vertebrae showed that they were built for striking.