''Soroavisaurus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

enantiornithean The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and cla ...

birds related to '' Avisaurus''. It lived during the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

of Argentina. The only known species, ''S. australis'', is known from

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s collected from the Lecho Formation (

Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval ...

age) of Estancia El Brete, in the southern tip of the province of

Salta Salta () is the capital and largest city in the Argentine province of the same name. With a population of 618,375 according to the 2010 census, it is also the 7th most-populous city in Argentina. The city serves as the cultural and economic ce ...

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

. A binominal name of this animal means "Southern sister Avisaur".

Description

The specimens are in the collection of the Fundación-Instituto Miguel Lillo, Tucumán. They are cataloged as PVL-4690, a -long left tarsometatarsus, and PVL-4048, which includes another left tarsometatarsus, -long and associated with the whole

hallux Toes are the digits (fingers) of the foot of a tetrapod. Animal species such as cats that walk on their toes are described as being '' digitigrade''. Humans, and other animals that walk on the soles of their feet, are described as being '' pl ...

, or digit I, and four intermediate phalanges. PVL-4048 was previously described as ''"Avisaurus sp."'' (see '' Avisaurus'').Chiappe, Luis M. (1993) "Enantiornithine (Aves) Tarsometatarsi from the Cretaceous Lecho Formation of Northwestern Argentina." "American Museum Novitates" December 27, 1993 Number 3083, 27pp. PVL-4048, the largest undoubted individual of ''Soroavisaurus'', indicates an animal with a length of , hip height of , and weight of . PVL-4033, a

tibiotarsus The tibiotarsus is the large bone between the femur and the tarsometatarsus in the leg of a bird. It is the fusion of the proximal part of the tarsus with the tibia. A similar structure also occurred in the Mesozoic Heterodontosauridae. These s ...

, probably belongs to a very large ''S. australis'', with a length of , hip height of , and weight of .

Phylogeny

The cladogram below is from Wang ''et al.'', 2022: Key to letters: ''b'' = '' Boluochia''
''c'' = ''

Cathayornis ''Cathayornis'' is a genus of enantiornithean birds from the Jiufotang Formation of Liaoning, People's Republic of China. It is known definitively from only one species, ''Cathayornis yandica'', one of the first Enantiornithes found in China. Se ...

''
''e'' = '' Enantiophoenix''
''f'' = '' Houornis''
''h'' = ''

Longipteryx ''Longipteryx'' is a genus of prehistoric bird which lived during the Early Cretaceous ( Aptian stage, 120.3 million years ago). It contains a single species, ''Longipteryx chaoyangensis''. Its remains have been recovered from the Jiufotang Form ...

''
''i'' = '' Parabohaiornis''
''j'' = '' Pterygornis''
''l'' = ''

Vorona ''Vorona'' ( ; Malagasy for "bird", ''V. berivotrensis'', "from Berivotra") is a monotypic genus of prehistoric birds. It was described from fossils found in a Maevarano Formation quarry near the village of Berivotra, Mahajanga Province, Madag ...

''
''m'' = '' Yuanjiawaornis''
''n'' = '' Yungavolucris''

Paleobiology

Due to their large size and strong talons, ''Soroavisaurus'' could occupy the same ecological niche as extanct

birds of prey Birds of prey or predatory birds, also known as raptors, are hypercarnivorous bird species that actively hunt and feed on other vertebrates (mainly mammals, reptiles and other smaller birds). In addition to speed and strength, these predat ...

, noticing prey from afar on the plains or in water.

References

Avisaurids Bird genera Maastrichtian life Cretaceous birds of South America Late Cretaceous animals of South America Cretaceous Argentina Fossils of Argentina Lecho Formation Fossil taxa described in 1993 Taxa named by Luis M. Chiappe {{paleo-bird-stub