''Lavocatavis'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of prehistoric

bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

from the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

Algeria Algeria, officially the People's Democratic Republic of Algeria, is a country in the Maghreb region of North Africa. It is bordered to Algeria–Tunisia border, the northeast by Tunisia; to Algeria–Libya border, the east by Libya; to Alger ...

. A fossilized

femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the knee. In many quadrupeds, four-legged animals the femur is the upper bone of the hindleg. The Femo ...

was described from the Glib Zegdou Formation in

2011 The year marked the start of a Arab Spring, series of protests and revolutions throughout the Arab world advocating for democracy, reform, and economic recovery, later leading to the depositions of world leaders in Tunisia, Egypt, and Yemen ...

and is the only known specimen of ''Lavocatavis''. The species was designated ''L. africana''.

Discovery and naming

The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

of ''Lavocatavis'', UM HGL 51-55, consists of an almost complete right femur. It is reasonably well preserved in the middle, but fragmentary at both ends. It originates from layer HGL 51 of the Glib Zegdou Formation of Algeria. The generic epithet (meaning "Lavocat's bird") was named in honor of René Lavocat, the person who first reported the earth layer of the holotype.

Paleobiogeography

The oldest phorusrhacids are from South America and Antarctica, so if this genus were indeed a phorusrhacid, the ancestors of ''Lavocatavis'' might have migrated into Africa from the west. During the Eocene, the Atlantic Ocean separated South America from Africa by at least , ruling out a land migration. For a flightless terrestrial bird like ''Lavocatavis'', the only means of entering Africa would have been through rafting on

floating island A floating island is a mass of floating aquatic plants, mud, and peat ranging in thickness from several centimeters to a few meters. Sometimes referred to as ''tussocks'', ''floatons'', or ''suds'', floating islands are found in many parts of t ...

s or

island hopping Leapfrogging was an amphibious military strategy employed by the Allies in the Pacific War against the Empire of Japan during World War II. The key idea was to bypass heavily fortified enemy islands instead of trying to capture every island i ...

. Currents traveled westward in the South Atlantic during the early Paleocene, making it unlikely that phorusrhacoids traveled on floating islands. The ancestors of ''Lavocatavis'' most likely traveled between very large islands that existed on what are now the submerged

Rio Grande Rise The Rio Grande Rise, also called the Rio Grande Elevation or Bromley Plateau, is an aseismic ocean ridge in the southern Atlantic Ocean off the coast of Brazil. Together with the Walvis Ridge off Africa, the Rio Grande Rise forms a V-shaped str ...

and Walvis Ridge. However, it is also possible that the ancestors of ''Lavocatavis'' retained some of their flight ability and were able to travel between islands with more ease than flightless birds. If this was the case, ''Lavocatavis'' became flightless independently of other flightless phorusrhacoids, in a case of

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...

Classification

Along with '' Eleutherornis'', it has been considered as a possible member of the family

Phorusrhacidae Phorusrhacids, colloquially known as terror birds, are an extinct family of large carnivorous, mostly flightless birds that were among the largest apex predators in South America during the Cenozoic era. Their definitive fossil records range from ...

outside the Americas, but the taxonomic identity of both taxa is considered highly questionable.Supplementary Information
/ref> However, Gerald Mayr suggested that '' Eleutherornis'' more closely resembles other cariamiforms ''

Strigogyps ''Strigogyps'' is an extinct genus of prehistoric bird from the Middle Eocene to Early Oligocene of France and Germany. It was probably around the size of a large chicken or a guan, weighing not quite . Apparently, as indicated by the ratio of l ...

'' and '' ?Dynamopterus anthracinus'', while ''Lavocatavis'' is likely more related to a possible paleognath ''

Eremopezus ''Eremopezus'' is a prehistoric bird genus, possibly a palaeognath. It is known only from the fossil remains of a single species, the huge and presumably flightless ''Eremopezus eocaenus''. This was found in Upper Eocene Jebel Qatrani Formation ...

'', questioning the taxonomic placement of both taxa as phorusrhacids. Because the remains are too fragmentary, phylogenetic analysis cannot be conducted for both genera, and their relationships to phorusrhacids are only considered tentative.

References

Extinct flightless birds Eocene birds Fossil taxa described in 2011 Paleogene birds of Africa {{paleo-neornithine-stub