A new tristichopterid (Osteolepiformes: Sarcopterygii) from the Mandagery Sandstone (Late Devonian, Famennian) near Canowindra, NSW, Australia

Abstract

AbstractA new member of the Tristichopteridae (=Eusthenopteridae), Mandageria fairfaxi gen. et sp. nov., is described from the Late Devonian (Famennian) Mandagery Sandstone outcropping near Canowindra, NSW, Australia. It is represented by several complete or partial heads and bodies, preserved as natural moulds. Mandageria shares derived characters with the Late Famennian tristichopterid Eusthenodon wängsjöi from East Greenland; the pineal plate series is large and kite-shaped and is posterior to the middle of the parietals, the intertemporal does not contact the posterior supraorbital, a posterior process of the premaxilla divides the apical fossa, the anteriormost premaxillary tooth is enlarged, the postorbital is excluded from the orbit by a supraorbital–lacrimal contact, and the coronoids lack marginal teeth except posteriorly. Mandageria fairfaxi differs from Eusthenodon in superficial fusion of the supratemporal, tabular and postparietals, in the lateral extrascapulars being separated by only 2–3 mm in the midline anteriorly, and in having proportionately smaller scales. It also has an elongate supracleithrum, which is probably autapomorphic. The postcranial skeleton is comparable to that of the Frasnian genus Eusthenopteron, but differs in the more posterior position of the median fins, the poorly ossified vertebral column, and the flattened ectepicondyle. Mandageria fairfaxi is the second osteolepiform described from Canowindra (the first, Canowindra grossi) and, other than the now-reinterpreted Marsdenichthys, the first tristichopterid described from Australia.