Marine invertebrate fossils from the Permian–Triassic boundary beds of two core sections in the northern Perth Basin, Western Australia

Marine macroinvertebrate fossils from two petroleum exploration cores, Apium-1 and Redback-2, are described, and found to contain two separate assemblages. The assemblage from the Apium-1 core was recovered from an ca 5-m-thick interval (2756.35–2751.28 m) in the basal Hovea Member (‘inertinitic interval’) of the Kockatea Shale and includes the following forms: ?Spinomarginifera sp., Cimmeriella sp., ?Etherilosia sp., Elivina sp., Cleiothyridina sp., and Paeckelmanelloidea gen. et. sp. indet. (all brachiopods). The age of this assemblage is interpreted as Changhsingian, as constrained by its association with the palynofloral Dulhuntyispora parvithola Zone. The assemblage from the Redback-2 core was recovered from the ‘sapropelic interval’ of the Hovea Member of the Kockatea Shale between 3806 m and 3786 m and comprises the following forms: Lingulidae gen. et sp. indet. (brachiopod), Claraia perthensis Dickins & McTavish, Crittendenia cf. australasiatica (Krumbeck), ?Paralledon sp. (bivalves), ?Otoceras sp. (ammonoid), Microconchus utahensis Zaton, Taylor & Vinn (microconchid) and Magniestheria mangaliensis (Jones) (spinicaudatan). Among these, the first local appearances of the lingulid species, ?Otoceras sp. and M. mangaliensis are associated with the palynofloral Protohaploxypinus microcorpus Zone and are interpreted as latest Changhsingian in age. Other occurrences of the Redback-2 fossil assemblage overlap with the palynofloral Kraeuselisporites saeptatus Zone and are considered to be of earliest Triassic (Griesbachian) age.