Wilaru Explained

Wilaru is an extinct genus of bird, possibly a presbyornithid, from Australia during the Late Oligocene to Early Miocene, around 24-22 million years ago. The type species is Wilaru tedfordi, and the second species is Wilaru prideauxi.

Discovery and naming

The type species, Wilaru tedfordi, was described from fossil material collected from Lake Pinpa, Lake Palankarinna and Billeroo Creek, in the Lake Eyre Basin of north-eastern South Australia. 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 W. tedfordi honours American palaeontologist 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.[1]

The second species, Wilaru prideauxi, was first named in 2016 after the Australian vertebrate paleontologist Gavin Prideaux, who worked on the geological strata where its specimen was discovered and on the Australian mammals from the Oligocene to Miocene epochs. W. prideauxi was properly named in 2020 after the authors republished the study as a correction with Zoobank Registration.[2] [3]

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.

Classification

It was originally classified as a stone-curlew, but subsequently it was argued to be the youngest member of the extinct family Presbyornithidae instead.[4] The discovery of a similar Eocene presbyornithid Murgonornis archeri also supported this taxonomic assignment.[3] However, Wilaru was recovered within various positions of Galloanserae based on phylogenetic analyses in 2024, making its identity as a presbyornithid questionable.[5]

Notes and References

  1. Book: Walter E. Boles. Melanie A. Finch . Rene H. Hofheins . Patricia Vickers-Rich . Mary Walters . Thomas H. Rich . amp . 2013 . A fossil stone-curlew (Aves: Burhinidae) from the Late Oligocene/Early Miocene of South Australia . Ursula B. Göhlich . Andreas Kroh . Paleornithological Research 2013. Proceedings of the 8th International Meeting of the Society of Avian Paleontology and Evolution, Vienna, 2012 . Naturhistorisches Museum Wien . 43–61 . 978-3-902421-82-1 .
  2. V.L.. De Pietri. R.P.. Scofield. N.. Zelenkov. W.E.. Boles. T.H.. Worthy. 2020. Correction to 'The unexpected survival of an ancient lineage of anseriform birds into the Neogene of Australia: the youngest record of Presbyornithidae'. Royal Society Open Science . 7 . 11 . 201430 . 10.1098/rsos.201430 . 33391810 . 2054-5703 . 7735352.
  3. Worthy . Trevor H. . De Pietri . Vanesa L. . Scofield . R. Paul . Hand . Suzanne J. . 2023-03-20 . A new Eocene species of presbyornithid (Aves, Anseriformes) from Murgon, Australia . Alcheringa: An Australasian Journal of Palaeontology . 47 . 4 . 416–430 . 10.1080/03115518.2023.2184491 . 257679005 . 0311-5518. free . 2023Alch...47..416W .
  4. V.L.. De Pietri. R.P.. Scofield. N.. Zelenkov. W.E.. Boles. T.H.. Worthy. 2016. The unexpected survival of an ancient lineage of anseriform birds into the Neogene of Australia: the youngest record of Presbyornithidae . Royal Society Open Science . 3 . 2 . 150635 . 10.1098/rsos.150635 . 4785986 . 26998335. 2016RSOS....350635D . 2054-5703 .
  5. Musser . G. . Clarke . J. A. . A new Paleogene fossil and a new dataset for waterfowl (Aves: Anseriformes) clarify phylogeny, ecological evolution, and avian evolution at the K-Pg Boundary . 2024 . PLOS ONE . 19 . 7 . e0278737 . 10.1371/journal.pone.0278737 . free . 39078833 . 11288464 .