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Taxonomy from Lynne Bean 2021. Archaeomaene tenuis can be easily distinguished from the much more common Cavenderichthys talbragarensis by the more posterior dorsal fin. Diagnosis for Archaeomaene tenuis from Bean 2021 (modified from Woodward 1895): “ Same as family with the following additional characteristics. The supraorbital sensory canal has branched (ramified) tubules [*]. The dorsal fin is placed opposite to the anal fin. Pelvic, dorsal and anal fins are without fringing fulcra [*]. There are six uroneurals; the epaxial margin of the caudal fin has a few long basal fulcra and long fringing fulcra extending along the whole margin; both leading margins of the caudal fin have a single principal ray. Scales are elasmoid cycloidal [*]. (An asterisk [*] notes a uniquely derived character or autapomorphy of the genus).” Line drawing from Bean 2021, p. 116: References: Woodward, A.S., 1895. The fossil fishes of the Talbragar Beds (Jurassic?). Geological Survey of New South Wales, Palaeontology. Memoir 9: 1‒27. Bean, Lynne (2021) Revision of the Mesozoic freshwater fish clade Archaeomaenidae, Alcheringa: An Australasian Journal of Palaeontology, 45:2, 217-259, DOI: 10.1080/03115518.2021.1937700 Bean, Lynne (2021) The morphological revisions of freshwater fish from Late Jurassic - Early Cretaceous sites in Australia and other Gondwanan continents leads to new phylogenetic hypotheses of relationships among stem teleosts. Thesis (PhD) DOI: 10.25911/5JM5-WY12

One of the common coniferous plant fossils found at the Talbragar site is Agathis jurassica. The genus Agathis is extant, representing a small group of some 21 species mainly distributed in Australasia, belonging to the same family (Araucariaceae) as Wollemia. Together with a fishtail. Key references: White. M.E., 1981a. Fish beds reveal lush fossil forest. Australian Natural History 20 (7), 227-230. White. M.E., 1981b. Revision of the Talbragar Fish Bed Flora (Jurassic) of New South Wales. Records of the Australian Museum 33 (15), 695-721. Woodward, A.S., David, T.W.E. and Pittman, E.F., 1895. The fossil fishes of the Talbragar Beds (Jurassic?), with a note on their stratigraphical relations. Memoir Geological Survey of New South Wales, Palaeontology 9, 1-27. Frese M, Gloy G, Oberprieler RG, Gore DB (2017) Imaging of Jurassic fossils from the Talbragar Fish Bed using fluorescence, photoluminescence, and elemental and mineralogical mapping. PLoS ONE 12(6): e0179029. https://doi.org/10.1371/journal. pone.0179029

Diagnosis for the genus (emended from Bean 2006, based on a unique combination of characters): "Small fusiform teleost of standard length reaching 98 mm and about 150 mm maximum length. Snout length approximately half of the orbital diameter; cranial length is 90% of body height. All cranial bones without ornamentation; at least two large pores of the supraorbital canal on each frontal bone. Quadrate-mandibular articulation below anterior half of orbit; hyomandibula without preopercular process; four short and broad sensory tubules on lower limb of preopercle, one at angle and one on dorsal limb. Anterior ceratohyal short; with six thin acinaciform branchiostegal rays; with four to six spathiform branchiostegal rays associated with the posterior ceratohyal. Thirty-eight to 45 vertebrae, 25 with autogenous neural arches in abdominal region and 16 with fused neural and hemal arches in caudal region; 22–26 pairs of ribs; epipleural bones in mid-body region. With 12 or 13 pectoral rays and 9 pelvic rays. Seven or eight hypurals; small diastema between hypurals 2 and 3; dorsal lobe of caudal fin has 7–10 epaxial procurrent rays; ventral lobe has two segmented procurrent rays and 4–6 unsegmented procurrent rays. " Line drawing from Bean & Arratia 2019, p. 16: References: Bean, Lynne (2006) The leptolepid fish Cavenderichthys talbragarensis (Woodward, 1895) from the Talbragar Fish Bed (Late Jurassic) near Gulgong, New South Wales. Records of the Western Australian Museum 23: 43-76 (2006). Werner W. Schwarzhans, Timothy D. Murphy & Michael Frese (2019) Otoliths in situ in the stem teleost Cavenderichthystalbragarensis (Woodward, 1895), otoliths in coprolites, and isolated otoliths from the Upper Jurassic of Talbragar, New South Wales, Australia, Journal of Vertebrate Paleontology, DOI: 10.1080/02724634.2018.1539740. Bean, L. B. & Arratia, G., (2019). Anatomical revision of the Australian teleosts Cavenderichthys talbragarensis and Waldmanichthys koonwarri impacting on previous phylogenetic interpretations of teleostean relationships. Alcheringa 44, 121–159. ISSN 0311-5518.