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.

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.

[6] A 2010 study by Degrange and colleagues of Andalgalornis, based on Finite Element Analysis using CT scans, estimated its bite force and stress distribution in its 37-centimetre-long (15 in) skull, and showed that it had lost a large degree of intracranial immobility (mobility of skull bones in relation to each other), as was also the case for other large phorusrhacids.

These researchers interpreted this loss as an adaptation for enhanced rigidity of the skull, and compared to the modern red-legged seriema and white-tailed eagle, the skull of the phorusrhacid showed relatively high stress under sideways loadings, but low stress where force was applied up and down, and in simulations of "pullback".

Due to the relative weakness of the skull at the sides and middle, these researchers considered it unlikely that Andalgalornis engaged in potentially risky behavior that involved using its beak to subdue large, struggling prey.