Wilaru

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Wilaru
Temporal range: 26–22  Ma
Postcranial elements of Wilaru compared to Presbyornis pervetus.jpg
Postcranial elements of Wilaru compared to Presbyornis pervetus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Family: Presbyornithidae
Genus: Wilaru
Boles et al., 2013
Type species
Wilaru tedfordi
Boles et al., 2013
Other species
  • W. prideauxi
    De Pietri et al., 2020 [1]

Wilaru is an extinct genus of presbyornithid bird from Australia during the Late Oligocene to Early Miocene, around 26-22 million years ago. [2] The type species is Wilaru tedfordi, and the second species is Wilaru prideauxi. [3]

Contents

Discovery and naming

Postcranial elements of presbyornithids (Wilaru, Presbyornis and Teviornis) and southern screamer Postcranial elements of Presbyornithidae and southern screamer.jpg
Postcranial elements of presbyornithids (Wilaru, Presbyornis and Teviornis ) and southern screamer

The type species, Wilaru tedfordi, was described from fossil material collected from Lake Pinpa, Lake Palankarinna and Billeroo Creek, specfically in the Namba Formation of Lake Eyre Basin, 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. [4]

The second species, Wilaru prideauxi, was first named in 2016 after the Australian vertebrate paleontologist Gavin Prideaux, who worked on Lake Ngapakaldi of the Wipajiri Formation in South Australia where the specimen of W. prideauxi was discovered and on various Australian mammals which lived during the Oligocene to Miocene epochs. [3] W. prideauxi was properly named in 2020 after the authors republished the study as a correction with Zoobank Registration. [1] [2] The holotype of W. tedfordi is a left humerus (SAMA P48925), while the holotype of W. prideauxi is a right tarsometatarsus (SAMA P53136). [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. [3]

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. [3]

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. [3]

Classification

It was originally classified as a stone-curlew, [4] but subsequently it was argued to be the youngest member of the extinct family Presbyornithidae instead. [3] The discovery of a similar Eocene presbyornithid Murgonornis archeri also supported this taxonomic assignment. [2] A 2024 phylogenetic analysis recovered Wilaru within various positions of Galloanserae, making its identity as a presbyornithid questionable. [5] However, a 2025 study which reported a nearly complete skull of Vegavis revised the phylogenetic analyses of Galloanserae and recovered Wilaru as a member of the Presbyornithidae within Anseriformes. [6]

References

  1. 1 2 De Pietri, V.L.; Scofield, R.P.; Zelenkov, N.; Boles, W.E.; Worthy, T.H. (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. doi:10.1098/rsos.201430. ISSN   2054-5703. PMC   7735352 . PMID   33391810.
  2. 1 2 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. Bibcode:2023Alch...47..416W. doi: 10.1080/03115518.2023.2184491 . hdl: 1959.4/unsworks_83108 . ISSN   0311-5518. S2CID   257679005.
  3. 1 2 3 4 5 6 7 De Pietri, V.L.; Scofield, R.P.; Zelenkov, N.; Boles, W.E.; Worthy, T.H. (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. Bibcode:2016RSOS....350635D. doi:10.1098/rsos.150635. ISSN   2054-5703. PMC   4785986 . PMID   26998335.
  4. 1 2 Walter E. Boles; Melanie A. Finch; Rene H. Hofheins; Patricia Vickers-Rich; Mary Walters & Thomas H. Rich (2013). "A fossil stone-curlew (Aves: Burhinidae) from the Late Oligocene/Early Miocene of South Australia". In Ursula B. Göhlich & Andreas Kroh (eds.). Paleornithological Research 2013. Proceedings of the 8th International Meeting of the Society of Avian Paleontology and Evolution, Vienna, 2012 (PDF). Naturhistorisches Museum Wien. pp. 43–61. ISBN   978-3-902421-82-1.
  5. Musser, G.; Clarke, J. A. (2024). "A new Paleogene fossil and a new dataset for waterfowl (Aves: Anseriformes) clarify phylogeny, ecological evolution, and avian evolution at the K-Pg Boundary". PLOS ONE. 19 (7). e0278737. doi: 10.1371/journal.pone.0278737 . PMC   11288464 . PMID   39078833.
  6. Torres, Christopher R.; Clarke, Julia A.; Groenke, Joseph R.; Lamanna, Matthew C.; MacPhee, Ross D. E.; Musser, Grace M.; Roberts, Eric M.; O’Connor, Patrick M. (2025). "Cretaceous Antarctic bird skull elucidates early avian ecological diversity". Nature. 638 (8049): 146–151. doi:10.1038/s41586-024-08390-0. ISSN   1476-4687.