Austrotoma excavata

The shell features a subsutural fold that ranges from weak to moderate in prominence. Its spiral sculpture is restricted entirely to the base, while axial ribs appear only on the early whorls of the spire. The shoulder angle is sharply defined, characterized by a broad, smooth keel. ^{[2] [3]}

Fossils have been found in Middle Miocene strata at Kaipara, New Zealand.</ref name="Powell" />

• Beu, A.G. & Maxwell, P.A. (1990) Cenozoic Mollusca of New Zealand. New Zealand Geological Survey Paleontological Bulletin, 58, 1–518.
• Maxwell, P. A. (2009). Cenozoic Mollusca. Pp 232-254 in Gordon, D. P. (ed.) New Zealand inventory of biodiversity. Volume one. Kingdom Animalia: Radiata, Lophotrochozoa, Deuterostomia. Canterbury University Press, Christchurch.