Phorusrhacidae

Phorusrhacidae Temporal range: Middle Eocene – Late Pleistocene[1][2] ~43–0.1 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Reconstructed skeleton of Titanis walleri, Florida Museum of Natural History
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Cariamiformes
Superfamily:	†Phorusrhacoidea Ameghino, 1889
Family:	†Phorusrhacidae Ameghino, 1889[3]
Type species
†Phorusrhacos longissimus Ameghino, 1887
Subfamilies
†Phsyornithinae †Mesembriornithinae †Patagornithinae †Phorusrhacinae †Psilopterinae
Synonyms
Family synonymy Pelecyornidae Ameghino, 1891 Brontornithidae Moreno & Mercerat, 1891 Darwinornithidae Moreno & Mercerat, 1891 Stereornithidae Moreno & Mercerat, 1891 Patagornithidae Mercerat, 1897 Hermosiornidae Rovereto, 1914 Psilopteridae Dolgopol de Saez, 1927 Devincenziidae Kraglievich, 1932 Mesembriorniidae Kraglievich, 1932

Phorusrhacids, colloquially known as terror birds, are an extinct family of large carnivorous, mostly flightless birds^[a] that were among the largest apex predators in South America during the Cenozoic era. Their definitive fossil records range from the Middle Eocene to the Late Pleistocene around 43 to 0.1 million years ago,^[1][2] though some specimens suggest that they were present since the Early Eocene.

They ranged in height from 1 to 3 m (3 to 10 ft). One of the largest specimens from the Early Pleistocene of Uruguay, possibly belonging to Devincenzia, would have weighed up to 350 kilograms (770 lb).^[5][6] Their closest modern-day relatives are believed to be the 80-centimetre-tall (31 in) seriemas. Titanis walleri, one of the larger species, is known from Texas and Florida in North America. This makes the phorusrhacids the only known large South American predator to migrate north in the Great American Interchange that followed the formation of the Isthmus of Panama land bridge (the main pulse of the interchange began about 2.6 Ma ago; Titanis at 5 Ma was an early northward migrant).^[7]

It was once believed that T. walleri became extinct in North America around the time of the arrival of humans,^[8] but subsequent datings of Titanis fossils provided no evidence for their survival after 1.8 Ma.^[9] However, reports from Uruguay of new findings of phorusrachids such as a specimen of Psilopterus dating to 96,040 ± 6,300 years ago would imply that phorusrhacids survived in South America until the late Pleistocene.^[b]

Phorusrhacids may have even made their way into Africa and Europe, if the genus Lavocatavis from Algeria and Eleutherornis from France and Switzerland are included.^[10][11] However, the taxonomic placement of both taxa within phorusrhacids are considered highly questionable, and their remains are too fragmentary to be included in phylogenetic analyses.^[12][13][14] Possible specimens have also been discovered from the La Meseta Formation of Seymour Island, Antarctica, suggesting that this group had a wider geographical range in the Paleogene.^[15]

The closely related bathornithids occupied a similar ecological niche in North America across the Eocene to Early Miocene; some, like Paracrax, were similar in size to the largest phorusrhacids.^[16][17] At least one analysis recovers Bathornis as sister taxa to phorusrhacids, on the basis of shared features in the jaws and coracoid,^[18] though this has been seriously contested, as these might have evolved independently for the same carnivorous, flightless lifestyle.^[19]

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