Cooyoo

{{Short description|Extinct genus of ray-finned fishes}}

{{italic title}}

{{Speciesbox

| image = Cooyoo_australis_23.jpg

| fossil_range = {{fossil range|106.2|100.5|Late Albian}}

| image_caption = Reconstruction according to specimen "Wandah"

| taxon = Cooyoo australis

| parent_authority = Bartholomai & Lees,{{Cite journal

| last = Bartholomai

|author2=Lees

| title = Cretaceous actinopterygian (Class Pisces) Cooyoo australis from Queensland

| journal = Memoirs of the Queensland Museum

| year = 1987}} 1987

| authority = (Woodward, 1894)

| synonyms = *†Portheus australis Woodward, 1894

• †Xiphactinus australis (Woodward, 1894)

}}

Cooyoo ("fish" in the Yirandhali language) is an extinct genus of ichthyodectid ray-finned fish known from the Lower Cretaceous. It contains a single species, C. australis, known from the Albian-aged Toolebuc and Allaru Formations of Queensland, Australia. C. australis was originally named by Arthur Smith Woodward as a species of Portheus (now a probable synonym of Xiphactinus) in 1894, which was later amended to Xiphactinus.

Some phylogenetic studies have recovered it as an indeterminate ichthyodectiform, but later ones have found it to either be a sister of Unamichthys, or more recently a true ichthyodectid related to Ichthyodectes.{{Cite journal |last=Cavin |first=Lionel |last2=Forey |first2=Peter L. |last3=Giersch |first3=Samuel |date=2013 |title=Osteology of Eubiodectes libanicus (Pictet & Humbert, ) and some other ichthyodectiformes (Teleostei): phylogenetic implications |url=https://www.tandfonline.com/doi/full/10.1080/14772019.2012.691559 |journal=Journal of Systematic Palaeontology |language=en |volume=11 |issue=2 |pages=115–177 |doi=10.1080/14772019.2012.691559 |issn=1477-2019}}{{Cite journal |last=Yabumoto |first=Yoshitaka |last2=Hirose |first2=Koji |last3=Brito |first3=Paulo M. |date=2020-03-15 |title=A new ichthyodectiform fish, Amakusaichthys goshouraensis gen. et sp. nov. from the Upper Cretaceous (Santonian) Himenoura Group in Goshoura, Amakusa, Kumamoto, Japan |url=https://www.tandfonline.com/doi/full/10.1080/08912963.2018.1497022 |journal=Historical Biology |language=en |volume=32 |issue=3 |pages=362–375 |doi=10.1080/08912963.2018.1497022 |issn=0891-2963}}{{Cite journal |last=Cavin |first=Lionel |last2=Berrell |first2=Rodney W. |date=2019-01-02 |title=Revision of Dugaldia emmilta (Teleostei, Ichthyodectiformes) from the Toolebuc Formation, Albian of Australia, with comments on the jaw mechanics |url=https://www.tandfonline.com/doi/full/10.1080/02724634.2019.1576049 |journal=Journal of Vertebrate Paleontology |language=en |volume=39 |issue=1 |pages=e1576049 |doi=10.1080/02724634.2019.1576049 |issn=0272-4634}}{{Cite journal |last=Berrell |first=Rodney W. |last2=Boisvert |first2=Catherine |last3=Trinajstic |first3=Kate |last4=Siversson |first4=Mikael |last5=Alvarado-Ortega |first5=Jesús |last6=Cavin |first6=Lionel |last7=Salisbury |first7=Steven W. |last8=Kemp |first8=Anne |date=2020-04-02 |title=A review of Australia’s Mesozoic fishes |url=https://www.tandfonline.com/doi/full/10.1080/03115518.2019.1701078 |journal=Alcheringa: An Australasian Journal of Palaeontology |language=en |volume=44 |issue=2 |pages=286–311 |doi=10.1080/03115518.2019.1701078 |issn=0311-5518}}

Cooyoo was a dominant predator of the Eromanga Sea. As with all other ichthyodectids, it was a predator of smaller fish, and had large conical teeth to easily catch them.{{Cite news |last=Robertson |first=Joshua |date=2015-07-17 |title=100 million-year-old fossils shed new light on Australia’s ancient inland sea |url=https://www.theguardian.com/science/2015/jul/17/100-million-year-old-fossils-shed-new-light-on-australias-ancient-inland-sea |access-date=2024-06-12 |work=The Guardian |language=en-GB |issn=0261-3077}} In contrast, Cooyoo itself was a prey item for larger animals, as a skull has been found with potentially fatal bite marks, which are referable to a polycotylid plesiosaur, an ornithocheiroid pterosaur, or most likely the ichthyosaur Platypterygius.{{Cite journal |last=Wretman |first=Lovisa |last2=Kear |first2=Benjamin P. |date=2014-04-03 |title=Bite marks on an ichthyodectiform fish from Australia: possible evidence of trophic interaction in an Early Cretaceous marine ecosystem |url=http://www.tandfonline.com/doi/abs/10.1080/03115518.2014.848692 |journal=Alcheringa: An Australasian Journal of Palaeontology |language=en |volume=38 |issue=2 |pages=170–176 |doi=10.1080/03115518.2014.848692 |issn=0311-5518}}

Cooyoo was initially described from a complete specimen with length about {{convert|1.1|m|ft}}, and other fossil remains have been found including near-complete skulls.{{Cite news |date=2015-07-17 |title=Fossils of giant fish unearthed in outback Qld |url=https://www.abc.net.au/news/2015-07-17/ancient-fish-fossils-unearthed-in-outback-qld/6626890 |access-date=2024-06-12 |work=ABC News |language=en-AU}} In 2011, a {{convert|2.5|m|ft}} long intact fossil, nicknamed "Wandah", was discovered in north-west Queensland. According to Rob Levers, Kronosaurus Korner museum founder and chairman, it was possible to detect the fish in the stomach of that specimen. Cooyoo is the largest bony fish known from the Eromanga Sea.{{Cite web |title=Kronosaurus Korner - Fish |url=https://www.kronosauruskorner.com.au/museum/collections/fish |access-date=2023-07-06 |website=www.kronosauruskorner.com.au}}{{Cite news |date=2023-02-28 |title=Tourists unearth 100 million-year-old marine predator in western Queensland |url=https://www.abc.net.au/news/2023-03-01/richmond-cooyoo-australis-fish-fossil-rare-find/102031456 |access-date=2023-03-03 |work=ABC News |language=en-AU}}