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. The following cladogram shows the position of Andalgalornis following a 2015 analysis: 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. Phorusrhacids are though to have been ground predators or scavengers, and have often been considered apex predators that dominated Cenozoic South America in the absence of mammalian predators, though they did co-exist with some large, carnivorous borhyaenid mammals. Earlier hypotheses of phorusrhacid feeding ecology were mainly based on them possessing large skulls with hooked beaks rather than through detailed hypotheses and biomechanical studies, and such studies of their running and predatory adaptations were only tested from the beginning of the 21st century. Alvarenga and Elizabeth Höfling made some general remarks about phorusrhacid habits in a 2003 article. They were flightless, as evidenced by the proportional size of their wings and body mass, and wing-size was more reduced in larger members of the group. They pointed out that the narrowing of the pelvis, upper maxilla, and thorax may have been adaptations for hunting in regions with high vegetation, which would permit greater agility when moving between vertical obstacles. The narrow upper maxilla would also help catching small animals hidden among tree trunks or stones.