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| Ferruaspis brocksi McCurry, Gill, Baranov, Hart, Slatyer & Frese, 2025 |
ABSTRACT
Osmeriformes represent an important component of freshwater ecosystems in Australia and New Zealand and yet are poorly represented in the fossil record in these countries. Here we describe a new species of fossil osmeriform from the Miocene of New South Wales. Australia. Phylogenetic analyses place the species as an early diverging member of the southern radiation of Osmeriformes. The fossils are embedded and mineralized in the iron oxide-hydroxide mineral goethite, resulting in an unusual degree of preservation. Preserved stomach contents indicate an opportunistic benthopelagic diet, evidenced by the remains of numerous phantom midge larvae (Chaoborus abundans), two insect wings, and a bivalve. Another bivalve (Unionidae) was found attached to the tail of one of the specimens. The distribution of melanophores indicates that the species was counter-shaded with two lateral stripes. Discovering this species west of the Great Dividing Range, with a population that includes a range of body sizes, suggests that at least this population if not the species spent its entire life in fresh water, unlike most extant Osmeriformes. The description of Ferruaspis brocksi highlights the ability of specimens with preserved soft tissues to reveal aspects of the paleobiology of extinct species.
SYSTEMATIC PALEONTOLOGY
TELEOSTEI Müller, 1846
EUTELEOSTEI Greenwood et al., 1967
OSMERIFORMES sensu Nelson, 2016
FERRUASPIDAE fam. nov.
Diagnosis: Slender, fusiform fish with an adipose fin. Distinguished from Stokellia and Retropinna and most Galaxiidae by the position of the dorsal fin that is positioned above pelvic fins in Ferruaspis and further posteriorly in other species. Distinguished from members of Retropinnidae, that have 17 or 18 primary caudal fin rays, by the presence of 19 primary caudal fin rays, the absence of a horny ventral keel, the slender structure of the last few neural spines and an absence of fusion of the first hypural and parhypural. Distinguished from Osmeridae, that possess 7–14 dorsal fin rays, by the presence of 16 dorsal fin rays as well as the tapered posterior margin of the anal fin. Distinguished from Galaxiidae, that have <16 primary caudal rays, by the number of primary caudal rays and a greater depth of the body.
FERRUASPIS gen. nov.
FERRUASPIS BROCKSI gen. et sp. nov.
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| Ferruaspis brocksi Habitus and fin positions (holotype AM F.154511). A, photograph of AM F.154511; B, C, line drawings showing the positions of the various fins, eye, and stomach. Scale bar equals 8 mm. |
Etymology—‘Ferru,’ from ferrum (Latin), meaning ‘iron,’ in relation to the iron-rich matrix that it was found in and ‘aspis,’ (Greek) meaning ‘shield,’ commonly applied to fossil fish. The specific epithet is named for Professor Jochen J. Brocks of Canberra, Australia, who discovered several of the specimens.
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| A school of Ferruaspis is chased by the extinct platypus, Obdurodon. Artwork: Alex Boersma |
Matthew R. McCurry, Anthony C. Gill, Viktor Baranov, Lachlan J. Hart, Cameron Slatyer and Michael Frese. 2025. The Paleobiology of A New osmeriform Fish Species from Australia. Journal of Vertebrate Paleontology. e2445684. DOI: doi.org/10.1080/02724634.2024.2445684
