Phorusrhacidae

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Phorusrhacids Fossil range: 62–2 Ma PreЄ Є O S D C P T J K Pg N Middle Paleocene - Late Pliocene
Paraphysornis.
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Aves Order: Gruiformes Family: Phorusrhacidae Ameghino, 1889[1]
Synonyms
see text

Phorusrhacids ("Rag-Bearers"), or terror birds, were a family of large carnivorous flightless birds that were the dominant predators in South America during the Cenozoic, 62–2 million years (Ma) ago. They were roughly 1–3 meters (3–10 feet) tall. Their closest modern-day relatives are believed to be the 0.8 m-tall seriemas. Titanis walleri, one of the larger species, is known from Texas and Florida in North America. This makes the phorusrhacids the only known example of large South American predators migrating north during the Great American Interchange (which occurred after the volcanic Isthmus of Panama land bridge rose ca. 3 Ma ago). It was once believed that T. walleri only became extinct around the time of the arrival of humans in North America,^[2] but subsequent datings of Titanis fossils have failed to provide evidence for their survival more recently than 1.8 Ma ago.^[3][4]

A recently discovered species, Kelenken guillermoi from Middle Miocene some 15 million years ago, discovered in Patagonia in 2006 represents the largest bird skull yet found. The fossil has been described as being a 28-inch (71 cm), nearly intact skull. The beak is roughly 18 inches (460 mm) long and curves in a hook shape that resembles an eagle's beak. It is thought that this new species would easily be able to swallow dog-sized prey. Most species described as Phorusrhacidae birds were smaller, 2 to 3 feet (0.6 - 0.9m) tall, but the new fossil belongs to a bird that probably stood about 10 feet (3.0 m) tall (3 m). Although scientists cannot be sure, they predict that the large terror birds were extremely nimble and quick runners able to reach speeds of 30 mph (48 km/h).^[5]

Phorusrhacids are colloquially known as "terror birds", because their larger species were apex predators and the most fearsome carnivores of their habitat (before, during and after the arrival of saber-toothed cats 2.5 Ma ago). Their wings had evolved into meathook-like structures that likely could be stretched out like arms to perform a hacking motion which theoretically would help in bringing down prey. Most of the smaller and some of the larger species are believed to have been fast runners.

Contents 1 Systematics and taxonomy 2 Synonyms 3 Popular culture 4 References 5 Further reading 6 External links

[edit] Systematics and taxonomy

Following the revision by Alvarenga and Höfling (2003), there are now 5 subfamilies, containing 14 genera and 18 species:^[6]

• Subfamily Brontornithinae — gigantic species, standing over 2 metres (6.6 ft) high. Placement in Phorusrhacidae and/or monophyly disputed.
  • Genus Brontornis (Early - Middle Miocene)
  • Genus Paraphysornis (Late Oligocene/Early Miocene of São Paulo State, Brazil)
  • Genus Physornis (Middle - Late Oligocene of Santa Cruz Province, Argentina)
• Subfamily Phorusrhacinae — gigantic species 3 metres (9.8 ft) high, but somewhat smaller and decidedly more nimble than the Brontornithinae
  • Genus Devincenzia (Late Miocene - Early Pliocene of NE Argentina and Arroyo Roman, Uruguay)
  • Genus Kelenken (Middle Miocene of Río Negro province, Argentina (largest known phorusrhacid))
  • Genus Phorusrhacos (Early - Middle Miocene)
  • Genus Titanis (Early - Late Pliocene)
• Subfamily Patagornithinae — medium-sized and very nimble species, standing around 1.5 metres (4.9 ft) high
  • Genus Patagornis (Santa Cruz Early - Middle Miocene of Santa Cruz Province, Argentina) - includes Morenomerceraria^{[verification needed]}, Palaeociconia, Tolmodus
  • Genus Andrewsornis (Middle - Late Oligocene of S Argentina)
  • Genus Andalgalornis (Late Miocene - Early Pliocene)
• Subfamily Psilopterinae — small species, standing 70–100 centimetres (2.3–3.3 ft) high
  • Genus Psilopterus (Deseado Middle Oligocene - Arroyo Chasicó Late Miocene of S and E Argentina)
  • Genus Procariama (Late Miocene - Early Pliocene of Catamarca Province, Argentina)
  • Genus Paleopsilopterus (Middle Paleocene of Itaboraí, Brazil)
• Subfamily Mesembriornithinae — medium-sized species, standing between 1 and 1.5 m high
  • Genus Mesembriornis (Late Miocene - Late Pliocene)

Alvarenga and Höfling do not include the Sophiornithidae from Europe in the phorusrhacoids; these have meanwhile turned out to be primitive relatives of owls.^[7]

[edit] Synonyms

The family Phorusrhacidae have been described under a number of synonyms:

• Phororhacosidae Ameghino, 1889
• Pelecyornidae Ameghino, 1891
• Brontornithidae Moreno & Mercerat, 1891
• Darwinornithidae Moreno & Mercerat, 1891
• Stereornithidae Moreno & Mercerat, 1891
• Phororhacidae Lydekker, 1893 (unjustified emendation)
• Patagornithidae Mercerat, 1897
• Hermosiornidae Rovereto, 1914
• Psilopteridae Dolgopol de Saez, 1927
• Devincenziidae Kraglievich, 1932
• Hermosiorniidae Kraglievich, 1932 (unjustified emendation)
• Mesembriorniidae Kraglievich, 1932
• Hermosiornithidae Wetmore, 1934 (unjustified emendation)

[edit] Popular culture

While not as widespread as dinosaurs, phorusrhacids are popular in various forms of fiction. Terror birds are featured in Robert E. Howard's 1931 short story "The Gods of Bal-Sagoth", in the 2008 film 10,000 BC, in the 2001 multi-player online role-playing game RuneScape, and in the 2006 documentary-style mini-series Prehistoric Park. Phorusrhacos also appears in episode 5 of the 2001 BBC documentary Walking With Beasts.

[edit] References

1. ^ Ameghino, F (1889). "Contribuición al conocimiento de los mamíferos fósiles de la República Argentina" (in Spanish). Actas Academia Nacional Ciencias de Córdoba 6: 1–1028. 
2. ^ Baskin, J. A. (1995). "The giant flightless bird Titanis walleri (Aves: Phorusrhacidae) from the Pleistocene coastal plain of South Texas." Journal of Vertebrate Paleontology, 15(4): 842-844.
3. ^ McFadden, B., Labs-Hochstein, J., Hulbert, R.C. Jr., and Baskin, J.A. (2006). "Refined age of the late Neogene terror bird (Titanis) from Florida and Texas using rare earth elements." Journal of Vertebrate Paleontology, 26(3): 92A (Supplement). PDF abstract
4. ^ McFadden, B., Labs-Hochstein, J., Hulbert, R.C. Jr., and Baskin, J.A. (2007). "Revised age of the late Neogene terror bird (Titanis) in North America during the Great American Interchange." Geology, 35(2): 123-126. doi:10.1130/G23186A.1 PDF fulltext
5. ^ Anitei, Stefan, "The Largest Terror Bird - It had the largest bird skull" [1]
6. ^ Alvarenga, Herculano M.F.; Höfling, Elizabeth (2003). "Systematic revision of the Phorusrhacidae (Aves: Ralliformes)". Papéis Avulsos de Zoologia 43 (4): 55–91. 
7. ^ Mayr, Gerald (2005-04-15). "Old World phorusrhacids (Aves, Phorusrhacidae): a new look at Strigogyps ("Aenigmavis") sapea (Peters 1987)" (abstract). PaleoBios 25 (1): 11–16. Retrieved on 2008-07-04. 

[edit] Further reading

• Bertelli, Sara; Chiappe, Luis M; Tambussi, Claudia (2007). "A New Phorusrhacid (Aves: Cariamae) from the Middle Miocene of Patagonia, Argentina". Journal of Vertebrate Paleontology 27 (2): 409–419. doi:10.1671/0272-4634(2007)27[409:ANPACF]2.0.CO;2. 
• Chiappe, Luis M; Bertelli, Sara (2006). "Skull morphology of giant terror birds". Nature 443: 929. doi:10.1038/443929a. 

[edit] External links

• Hooper Museum
• Terror Birds: Bigger and Faster (Science)
• Darren Naish: Tetrapod Zoology: "terror birds"
• Darren Naish: Tetrapod Zoology: "Raven, the claw-handed bird, last of the phorusrhacids" includes links to other articles on phorusrhacids