''Andrewsornis'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus of giant flightless predatory birds of the family Phorusrhacidae or "terror birds" that lived in

Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...

Argentina. Fossils have been found in the

Sarmiento Formation The Sarmiento Formation (Spanish: ''Formación Sarmiento''), in older literature described as the Casamayor Formation, is a geological formation in Chubut Province, Argentina, in central Patagonia, which spans around 30 million years from the mid- ...

, and possibly the

Agua de la Piedra Formation The Agua de la Piedra Formation (FAP, Spanish names include ''Estratos de Agua de la Piedra'' and ''Complejo Volcano-sedimentario del Terciario inferior'')Combina et al., 1994, p.418 is a Late Oligocene (Deseadan in the SALMA classification) geol ...

.''Andrewsornis''
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org

Discovery and naming

The holotype of ''Andrewsornis'' ( FM-P13417) was discovered on September 18, 1923 by John Bernard Abbott in Patagonia, who was participating in the " Marshall Field Paleontological Expeditions", a series of expeditions to Argentina and Bolivia from 1922 to 1927 by the

Field Museum of Natural History The Field Museum of Natural History (FMNH), also known as The Field Museum, is a natural history museum in Chicago, Illinois, and is one of the largest such museums in the world. The museum is popular for the size and quality of its educational ...

.Alvarenga, H. M., & Höfling, E. (2003). Systematic revision of the Phorusrhacidae (Aves: Ralliformes). ''Papéis Avulsos de Zoologia'', ''43''(4), 55-91.Patterson, B. (1941). A new phororhacoid bird from the Deseado formation of Patagonia. This holotype consists of: an incomplete skull, the lower jaws, the proximal part of the coracoid and the second and ungual

phalanges The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. ...

of digit II from the

pes Pes (Latin for "foot") or the acronym PES may refer to: Pes * Pes (unit), a Roman unit of length measurement roughly corresponding with a foot * Pes or podatus, a * Pes (rural locality), several rural localities in Russia * Pes (river), a river ...

. The fossils date to the

Deseadan The Deseadan ( es, Deseadense) age is a period of geologic time (29.0–21.0 Ma) within the Oligocene epoch of the Paleogene to the Early Miocene epoch of the Neogene, used more specifically within the SALMA classification of South America. It fo ...

of the middle-upper Oligocene of the Deseado Formation of Cabeza Blanca ( Chubut, Argentina). Two other specimens, a mandibular symphysis and incomplete left femur were collected from strata of the same age in

Santa Cruz Province Santa Claus, also known as Father Christmas, Saint Nicholas, Saint Nick, Kris Kringle, or simply Santa, is a legendary figure originating in Western Christian culture who is said to bring children gifts during the late evening and overnigh ...

. Bryan Patterson gave these fossils the name ''Andrewsornis abbotti'' in 1941, the generic name refers to Charles William Andrews "... as a tribute to the excellence of his research into fossil birds in general and specifically to the Phororhacidae". The species name, ''abbotti'', refers to John Bernard Abbott, the discoverer of the holotype. Patterson described him as "an experienced collector and preparer, whom I am in favor of his instructions on the practical aspects of paleontology."

Description

''Andrewsornis'' is so far the largest member of the subfamily Patagornithinae, though it has also been found to be a Phorusrhacine. The genus is generally very similar to '' Phorusrhacos'', but differs in that: the skull is slightly flatter, front edge of the antorbital fenestra is strongly sloping, the lower jaw is 39 cm long and slimmer than ''Phorusrhacos. With a length of 10 cm, the symphysis mandibulae is more similar to that in ''

Andalgalornis ''Andalgalornis'' is a genus of flightless predatory birds of the extinct family Phorusrhacidae (often called "terror birds") that lived in Argentina. The type and only species is ''A. steulleti''. Taxonomy ''Andalgalornis'' is known from an in ...

'' and '' Patagornis''. The Fenestrae Mandibulares are longer and larger than in ''Patagornis'' and ''Andalgalornis,'' have an oval shape.

Classification

In 2003 during their redescription of phorusrhacidae, Herculano Alvarenga and Elizabeth Hofling created a new subfamily, Patagornithinae, with ''Patagornis'' as the type genus, that included ''Andrewsornis'' and ''Andalgalornis''. ''Andrewsornis'' is similar to ''Patagornis'' and ''

'' in that they all are medium-sized phorusrhacids with slender, lightly built bodies, long and narrow mandibular symphyses, and long and slender tibiotarsi and tarsometatarsi. However, a phylogenetic analysis in 2015 by Degrange ''et al'' found ''Andrewsornis'' in a merged Phorusrhacinae and in polytomy with ''

Physornis ''Physornis'' is an extinct genus of giant flightless predatory birds of the family Phorusrhacidae or "terror birds", most closely related to '' Paraphysornis'', that lived in Argentina. The type species is ''P. fortis''. It lived during t ...

'' and '' Phorusrhacos'' as well. The following phylogenetic tree shows the internal relationships of Phorusrhacidae under the exclusion of ''Brontornis'' as published by Degrange and colleagues in 2015, which recovers a clade that contains ''Physornis'', ''Phorusrhacos'' and ''Andalgalornis'', among others.

References

External links

Genus Taxonomy
Phorusrhacidae Extinct flightless birds Oligocene birds Paleogene birds of South America Deseadan Paleogene Argentina Neogene Argentina Fossils of Argentina Fossil taxa described in 1941 Golfo San Jorge Basin Sarmiento Formation {{paleo-bird-stub