Very similar concretions, which are as much as 3 meter (9 ft) in diameter and called "Koutu Boulders", litter the beach between Koutu and Kauwhare points along the south shore of the Hokianga Harbour of Hokianga, North Island, New Zealand.
The type specimen was found in an iron-cemented sandstone concretion near Salina.
The specimen, cataloged as MLP 93-I-3-1, was found in the Cape Lamb deposits of Vega Island, Antarctica, in 1992, but was only described as a new species in 2005 because it consists of the very delicate remains of one bird embedded in a concretion, which had to be meticulously prepared for study.