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Temporal range: Late Miocene - Early Pliocene
Skull of Andalgalornis steulleti.png
CT scan of the skull of P 14357, holotype of Andalgalornis ferox in the collections of the Field Museum of Natural History
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Cariamiformes
Family: Phorusrhacidae
Genus: Andalgalornis
Patterson & Kraglievich, 1960
Species: A. steulleti
Binomial name
Andalgalornis steulleti
(Kraglievich, 1931)
  • Phororhacos steulleti

Kraglievich, 1931

  • Phororhacos deautieri

Kraglievich, 1931

  • Andalgalornis ferox

Patterson & Kraglievich, 1960

  • Phorohacos deautieri

Kraglievich, 1931

Andalgalornis was a genus of flightless predatory birds of the 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 Miocene to Early Pliocene Andalgala Formation.



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.[1] 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.[2]


  1. ^ Degrange, F.J.; Tambussi, C.P.; Moreno, K.; Witmer, L.M.; Wroe, S. (2010). "Mechanical Analysis of Feeding Behavior in the Extinct "Terror Bird" Andalgalornis steulleti (Gruiformes: Phorusrhacidae)". PLoS ONE. 5 (8): e11856. doi:10.1371/journal.pone.0011856. PMC 2923598Freely accessible. PMID 20805872. 
  2. ^ Tambussi, C. P.; De Mendoza, R.; Degrange, F. J.; Picasso, M. B. (2012). Evans, Alistair Robert, ed. "Flexibility along the Neck of the Neogene Terror Bird Andalgalornis steulleti (Aves Phorusrhacidae)". PLoS ONE. 7 (5): e37701. doi:10.1371/journal.pone.0037701. PMC 3360764Freely accessible. PMID 22662194.