''Wilaru'' is an extinct

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 ...

of bird of uncertain phylogenetic placement from the

Late Oligocene The Chattian is, in the geologic timescale, the younger of two ages or upper of two stages of the Oligocene Epoch/ Series. It spans the time between . The Chattian is preceded by the Rupelian and is followed by the Aquitanian (the lowest stage ...

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

of Australia. It was originally classified as a stone-curlew, but subsequently it was argued to be a member of the extinct family

Presbyornithidae Presbyornithidae is an extinct group of birds with a global distribution. They had evolved by the late Cretaceous period and became extinct during the early Miocene. Initially, they were believed to present a mix of characters shown by waterbirds ...

instead. It is either the oldest known burhinid or the youngest known presbyornithid. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

is ''Wilaru tedfordi''; genus also includes the second species ''Wilaru prideauxi''. The type species was described 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 ...

material collected from Lake Pinpa, Lake Palankarinna and Billeroo Creek, in the

Lake Eyre Basin The Lake Eyre basin ( ) is a drainage basin that covers just under one-sixth of all Australia. It is the largest endorheic basin in Australia and amongst the largest in the world, covering about , including much of inland Queensland, large porti ...

of north-eastern

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

. The genus name ''Wilaru'' is the term for “stone curlew” in the Diyari language of the Lake Eyre region. The specific epithet of the type species honours American

palaeontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...

Richard H. Tedford (1929–2011) of the American Museum of Natural History, who led the 1971 expedition to Lake Pinpa during which much of the descriptive material was collected.

Description and ecology

Compared to other presbyornithids, ''Willaru'' appeared to have been specialised to a more terrestrial lifestyle, based on its tarsometatarsal morphology. In particular, the latter ''W. prideauxi'' appears to have been more specialised towards terrestriality than the earlier ''W. tedfordi'', being larger and more robust, indicating a clear speciation towards this lifestyle and therefore a direct species sequence. Like many modern waterfowl, the ''Willaru'' species had spurs and knobs on their carpals. Like the closely related modern-day screamers, these were almost certainly used to fight, indicating perhaps territorial habits, as opposed to the more gregarious nature of earlier presbyornithids. ''Willaru'' co-existed with several anatid and anseranatid species, indicating that there was little ecological competition. It is possible that a speciation towards terrestriality might have spared it from competition with more derived waterfowl, allowing it to live longer than other presbyornithids.

References

Fossil taxa described in 2013 Birds described in 2013 Oligocene birds Miocene birds Prehistoric birds of Australia Presbyornithidae {{Paleo-bird-stub