''Enantiornis'' is a genus of

Enantiornithes 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 ...

. The

type Type may refer to: Science and technology Computing * Typing, producing text via a keyboard, typewriter, etc. * Data type, collection of values used for computations. * File type * TYPE (DOS command), a command to display contents of a file. * Ty ...

and only currently accepted species ''E. leali'' is from the Late Cretaceous Lecho Formation at

El Brete EL, El or el may refer to: Religion * El (deity), a Semitic word for "God" People * EL (rapper) (born 1983), stage name of Elorm Adablah, a Ghanaian rapper and sound engineer * El DeBarge, music artist * El Franco Lee (1949–2016), American po ...

, Argentina. It was described from specimen PVL-4035, a coracoid, proximal scapula and proximal

humerus The humerus (; ) is a long bone in the arm that runs from the shoulder to the elbow. It connects the scapula and the two bones of the lower arm, the radius and ulna, and consists of three sections. The humeral upper extremity consists of a roun ...

found close to each other and suspected to represent the left shoulder of a single individual.

Description

The genus and the larger group it belongs to, get their name from the reversed scapula-coracoid connection they possess compared to modern birds and the

hesperornithid Hesperornithes is an extinct and highly specialized group of aquatic avialans closely related to the ancestors of modern birds. They inhabited both marine and freshwater habitats in the Northern Hemisphere, and include genera such as '' Hesperorn ...

s that were their contemporaries: Enanti "opposite", ornis is "bird". Another left shoulder and wing, almost complete and found associated in one lump of rock, as well as a few isolated bones were also assigned to this species mainly based on size. It is among the largest enantiornithines discovered to date, with a length in life of around , hip height of , weight of , and wingspan comparable to herring gulls, around . Its ecological niche resembled that of a mid-sized vulture or

eagle Eagle is the common name for many large birds of prey of the family Accipitridae. Eagles belong to several groups of genera, some of which are closely related. Most of the 68 species of eagle are from Eurasia and Africa. Outside this area, just ...

Taxonomy and phylogeny

''E. leali'' was possibly fairly closely related to ''

Avisaurus ''Avisaurus'' (meaning "bird lizard") is a genus of enantiornithine bird from the Late Cretaceous of North America. Discovery ''Avisaurus archibaldi'' was discovered in the Late Cretaceous Hell Creek Formation of North America (Maastrichtian, fr ...

'', another genus of probably carnivorous enantiornithines, though its exact relationship is unclear. It was placed in a family of its own, Enantiornithidae. Other species from Asia that were previously placed in this genus are now split off. The former ''Enantiornis martini'' is now placed in ''

Incolornis ''Incolornis'' (meaning "inhabitant bird") is an extinct genus of basal birds from the Late Cretaceous (Coniacian, 89-86 mya). Remains have been found in the Bissekty Formation in Uzbekistan.Panteleyev, A.V. (1998) New species of enantiornithine ...

'', while the former ''Enantiornis walkeri'' is now tentatively assigned to '' Explorornis''. The reason for this is that these species were described when the diversity of enantiornithines was underestimated. As no hindlimb elements are known from ''Enantiornis'', it might include one of the El Brete enantiornithines known only from leg bones, namely '' Lectavis'', '' Soroavisaurus'' or '' Yungavolucris''. However, these apparently were all smaller than ''Enantiornis''. Hindlimb material tentatively assigned to '' Martinavis'' and '' Elbretornis'' seems somewhat and a lot too small, respectively, to represent ''Enantiornis''. The cladogram below is from Wang ''et al.'', 2022: Key to letters: ''b'' = ''

Boluochia ''Boluochia zhengi'' was an enantiornithine bird. It lived during the Early Cretaceous in the time span 121.6-110.6 mya ( late Aptian- early Albian) and is known from fossils found in the Jiufotang Formation of Liaoning province, People's Republ ...

''
''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''
''i'' = '' Parabohaiornis''
''j'' = '' Pterygornis''
''l'' = '' Vorona''
''m'' = '' Yuanjiawaornis''
''n'' = '' Yungavolucris''

References

Euenantiornitheans Maastrichtian life Cretaceous birds of South America Cretaceous Argentina Fossils of Argentina Lecho Formation Fossil taxa described in 1981 {{Theropod-stub