Article: Maastrichtian non-heteromorph ammonites from the Miria Formation, Western Australia
R. A. Henderson and K. J. McNamara
Twenty-two species of non-heteromorph ammonites, distributed among fourteen genera, are described from the Miria Formation, Western Australia. The species Kitchinites spathi, Gunnarites raggatti, Kossmaticeras (Natalites) brunnschweileri, Neograhamites carnarvonensis, and Brahmaites (Brahmaites) kossmati, and the subspecies Pachydiscus (Pachydiscus) neubergicus dissitus and P. (P.) jacquoti australis are described as new. Pachydiscus species shared with Western Europe date the Miria Formation as Maastrichtian, consistent with its age assignment based on Foraminifera. The Kossmaticeratidae is the most diverse family, contributing more than a third of the species. Maastrichtian records for the kossmaticeratid genera Gunnarites, Maorites, Kossmaticeras (Natalites), Grossouvrites, and Neograhamites, which previously had been thought to range no higher than Campanian, are new. The age attributable to the Miria Formation ammonite assemblage is reviewed in relation to standard Maastrichtian ammonite faunas from Western Europe.