Phorusrhacos – a scary bird

Phorusrhacos – a ‘terror bird’

The owner of the nickname ‘terror bird’ and one of the biggest carnivorous birds of all times. Its nickname is thanks to i.e. extremely molded wings equipped with claws.

Although it cannot fly, the nature adapted it to living on the Earth. It was not only a capable walker but also a scary predator whose biggest weapon was powerful and strong beak. Below, we present the Miocene representative of land hunters – the Phorusrhacos that is ‘the owner of wrinkled jaws’.


  • Kingdom: Animalia
  • Clade: Dinosauria
  • Class: Aves
  • Order: Cariamiformes
  • Family: †Phorusrhacidae
  • Subfamily: †Phorusrhacinae
  • Genus: †Phorusrhacos
  • Species: Phorusrhacos longissimus
The Phorusrhacos – the skull was around 60cm long.

The discovery

The Argentinian paleontologist, Florentino Ameghino, discovered a piece of the jawbone in the stratum of the Santa Cruz Formation at the beginning of 1887. In the same year, Ameghino described the founding as the remainder of the toothless mammal. He suggested that mandibular sockets for blood vessels are characteristic for mammals; therefore, the wrong scientific classification. The paleontologist gave this discovery a name Phorusrhacos longissimus.

Phorusrhacos remains, which have been found, come from a few towns situated in the Argentinian province, Santa Cruz.

The Phorusrhacos and Glyptodon


The first part of the name – Phorusrhacos is derived from two Greek words: phoros which can be translated as ‘the bearer’ or ‘the carrier’ and rhakos which means ‘wrinkles’, ‘folds’, ‘scars’. The second part of the name probably refers to the wrinkled jaw surface although there are also other theories on this topic. The gender name – longissimus is derived from Latin and translated as ‘very long’, literally ‘the longest’. This term has the connection with the size of the found jaw.

In 1889 Ameghino changed the genus name to the one, which was more grammatically correct – Phororhacos. However, the original one Phorusrhacos has the scientific priority.

This name defined the mammal from the moment of the discovery. It was only in 1891 – 4 years after the discovery of the unusual jaw – that the Phorusrhacos was classified as the bird.

The biggest flightless birds: 1- African ostrich; 2- Gastornis / Diatryma; 3- The elephant bird (†Aepyornis maximus); 4- The giant moa (Dinornis); 5- Phorusrhacos; 6- Moa; 7- Australian rhea; 8- Darwin rhea; 9- Cassowary; 10 –Emu (Dromaius novaehollandiae) ; 11- Dodo (Raphus cucullatus)


These enormous and scary flightless birds existed on the Earth around 20-25 million years ago. The Phorusrhacos order fell into the early and middle Miocene period.


The Phorusrhacos country was present Patagonia area. Nowadays, it is not a well-populated region in South America, which is situated on the territory of Argentina and Chile.

The Phorusrhacos habitat was grasslands and woodlands.




Despite its big size, the Phorusrhacos was light – it was 2.5 m (8.2 ft) tall and its weight was around 130kg (290 lb). Its general built was similar to present flightless birds. Similarly to them, it had clearly reduced wings.

The Phorusrhacos characteristic feature was sharp hook-tipped claws on not big wings. It also had huge claws on its toes thanks to which it caught hunted animals.

The main function of claws on its feet and wings was catching the prey. Flightless birds are usually presented as the ones, which hunted for small and medium animals, which could be difficult to be caught with the claw of the upper limb. It cannot be excluded that the bird helped itself using untypical claws while eating and not hunting. The other likely feature of hooks is the adjustment to fights with other representatives of this species.

1-Kelenken guillermoi; 2- Phorusrhacos; 3- Titanis walleri; 4- Gastornis parisiensis

The beak

The Phorusrhacos had a powerful hook-tipped beak characteristic for predatory birds. This part of its body could be the main weapon killing the prey. However, how could this flightless bird use the beak as the deadly weapon? We have two theories for that:

  • The first theory is based on observations of currently living South American seriemas birds – the closest Phorusrhacos Present seriemas catch the prey using its beak and then, they hit it on the ground. The result is not only knocking it out or killing but also numerous breaks. Thanks to this, the predator finds it easier to swallow the hunted food. Seriema’s claws are also used to portion the meat out. Many paleontologists support the theory that the Phorusrhacos used to hunt and kill their preys in a similar way.
  • According to the second theory, the Phorusrhacos killed by precise hits in crucial body parts using its beak, mainly the skull. This function of the beak is indicated by the hooked curve. The bird would use it then as a pickax, with which it attacks the prey from the above. The powerful beak combined with its hit would cause the skull break and the brain injury that would result in a quick death of the hunted animal.

The diet and the hunting tactics

Although it had the impressive size, it hunted for small insects and mammals. Bigger animals were left for its heavier relatives such as Brontornis.

Weak and small wings did not help it hunting; this function was taken over by its long and strong legs. It could easily chase for its potential prey on open and vast areas. It would have no difficulty in catching up relatively fast and not big animals.

However, it is possible that during hunting, the Phorusrhacos stood close to bushes and thin trees to become similar to the harmless tree trunk. Such predator became unnoticed by small mammals. When the prey came close enough, the bird jumped out in front of it and gave it no time for reaction. When it caught the prey, it tore it off with its claws to have better access to meat. It cannot be denied that the Phorusrhacos also ate carcass.

Probably, that flightless bird did not have to run a lot after its preys. It could act more efficiently by surprise.


Detailed information / size

The Phorusrhacos

  • Body height from the bottom to the top of its head: up to about 2.5 m (8.2 ft)
    • the back was at the height of about 140 cm (4ft 7in)
  • Weight: 130kg (290 lb)
  • Speed: around 50km/h (31 mph), slower than an ostrich
  • Dating: 20-13 million years ago
  • Era: early Miocene – middle Miocene
  • Distribution: South America, Patagonia

The Phorusrhacos – interesting facts

  • The Phorusrhacos skull could be up to 60cm long.
  • Close Phorusrhacos relatives were also considered to be one of the biggest predatory birds of all times: Titanis walleri (North America), Kelenken guillermoi and mentioned in the article, Brontornis (Brontornis burmeisteri) lived in South America, just as the Phorusrhacos. Kelenken was the biggest predatory bird- it had the biggest skull of all birds and its height was over 3m.
  • According to one scientific theory, grand predatory birds coexisted with last dinosaurs during the cretaceous period and hunted for them contributing to the total extinction of the cretaceous salamanders.
  • In the film 10.000 BC, there are Phorusrhacos, next to mammoths and the saber-toothed cat (smilodon), in the scene presenting hunting for the main character.


Dinosaur Database

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