The sediments of most common occurrence in the Auckland area are the Waitemata Group; interbedded mudstones and sandstones (turbidite sequences) with less common coarse volcanic derived grits and breccias: termed the Parnell Grit (after the type locality, behind the Parnell baths.)

It was in this type of formation that the specimen was found. The shark's teeth collected from the Parnell Grit has been identified by Dr Ian Keyes as Notorynchus primigenius (Agassiz). It is a member of the Family Hexanchidae which in living forms have 6 - 8 gill slits and the nearest living relative of the fossil would be Notorynchus cepedianus known as the "broadnosed 7-gill shark".