Richmondichthys is an extinct genus of large prehistoric marine ray-finned fish known from the Early Cretaceous. It contains a single species, R. sweeti from the late Albian-aged Allaru and Toolebuc Formations of Queensland, Australia.[1][2]
| Richmondichthys Temporal range:
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|---|---|
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| Holotype specimen | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | †Aspidorhynchiformes |
| Family: | †Aspidorhynchidae |
| Genus: | †Richmondichthys Bartholomai, 2004 |
| Species: | †R. sweeti
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| Binomial name | |
| †Richmondichthys sweeti (Etheridge Jr. & Woodward, 1891)
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| Synonyms | |
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At over 2 metres (6.6 ft) in length,[3] it is the largest known member of the Aspidorhynchidae, a group of primarily marine ray-finned fishes that were dominant throughout the latter half of the Mesozoic. It was initially described as a member of the aspidorhynchid genus Belonostomus,[4] with other fossil material being variously referred to Aspidorhynchus and Vinctifer, until it was described in its own genus in 2004, being named after the town of Richmond.[2]
Richmondichthys differs from other aspidorhynchid genera both in its immense size, lack of a prominent rostrum, and the lack of teeth while having hinged cheek bones. The latter appears to be an adaptation to filter-feeding for a planktivorous lifestyle, suggesting that Richmondichthys fed either by gulping plankton or moving through plankton swarms while ballooning its cheeks, in contrast to the predatory nature of other aspidorhynchids. It was heavily armored, potentially as a defense against predatory reptiles and fish. Unlike other aspidorhynchid genera which are known to have had wide distributions, Richmondichthys appears to have been restricted to the Eromanga Sea.[2]
In 2014, a complete specimen of Richmondichthys, nicknamed "Jeppy", was discovered near Marathon. Previously, the species was only known from skulls and fragmentary body remains. Following a decade of study, the fossil was returned to the Kronosaurus Korner museum in Richmond to be put on display.[3][5]
References
edit- ^ "PBDB Taxon". paleobiodb.org. Retrieved 2024-06-11.
- ^ a b c Bartholomai, Alan.; Bartholomai, Alan (2004). "The large aspidorhynchid fish, Richmondichthys sweeti (Etheridge Jnr and Smith Woodward, 1891) from Albian Marine deposits of Queensland, Australia". Memoirs of the Queensland Museum. 49 (2): 521––536.
- ^ a b "Scientists hope to rehome 110-million-year-old fish with scales like a crocodile and the diet of a whale". ABC News. 2023-05-10. Retrieved 2024-06-11.
- ^ Vic.), Royal Society of Victoria (Melbourne (1888). Transactions of the Royal Society of Victoria. Royal Society of Victoria.
- ^ "Australia's largest and most complete fossil of its kind returns to its outback home". ABC News. 2024-06-09. Retrieved 2024-06-11.