A diverse Late Pliocene fossil fauna and its paleoenvironment at Māngere, Auckland, New Zealand

ABSTRACT

Excavations at Māngere Wastewater Treatment Plant, Auckland, in 2020 provided New Zealand’s richest and most diverse fossil faunas of mid-Pliocene age (Waipipian Stage, 3.7–3.0 million years old). The vast excavated heap of sandy shell was extensively searched and sieved resulting in the recovery of 266 fossil taxa, (particularly rich in Mollusca including 77 Bivalvia, 105 Gastropoda, 32 Foraminifera, 13 Ostracoda, 11 Bryozoa). The fauna includes several undescribed taxa and additional warm-water Pliocene records for New Zealand. The fauna is most similar in composition and age to the fauna obtained from the Otahuhu Brewery well in the late 1940s. The fauna contains a mixture of taxa from many different shallow marine habitats, from intertidal and subtidal rocky shores and intertidal and shallow subtidal soft sediment flats to exposed and semi-exposed subtidal sandy habitats down to depths of 30–40 m. The shelly deposit is inferred to have accumulated in a current swept subtidal channel during one of the mid-Pliocene warm periods when sea level was high and had flooded an incised river valley that flowed from east to west across the Auckland region.

KEYWORDS:

• Pliocene
• Mollusca
• Foraminifera
• Ostracoda
• Otahuhu Formation
• Mangere Shellbed

Acknowledgements

We thank Watercare (Ron Boyle), Alex Parma and Charles Sweeney (Ghella Abergeldie Joint Venture) and Grant Reid (Waiau Pa Bulk Haulage) for allowing and facilitating access to the shelly sediment excavated during construction of shafts for the Central Interceptor; Dennis Gordon and Seabourne Rust for identifying bryozoans obtained from sediment inside the apertures of the fossil Maoristylus and Archaeostylus shells and attached to other larger shells. Eric Scott for providing a suite of imaged specimens he collected from Māngere, including several additional records. Felix Marx for identifying some of the marine vertebrate specimens. Bruce Marshall for examining and identifying some of the limpet specimens. We thank all the fossickers who have contributed additional specimens to make up this final list, particularly Eric and Heather Scott and Glenys and Kelvin Stace. Jill Kenny is thanked for allowing use of her draft work on the borehole stratigraphies of the Auckland area. Jennifer Carol of Auckland Museum and Eric Scott are thanked for photographing the specimens in Figures 5 and 6. We thank Austin Hendy and Kerry Walton and editor Liz Kennedy for their reviews that greatly improved the manuscript. On behalf of Auckland Museum and T.F.S., N.C. and W.B. we thank Watercare for their funding which allowed for a much fuller assessment of the fossil fauna and the collection of a suite of better-preserved specimens. We dedicate this publication to our late colleague and co-author, Dr Alan Beu, who was extremely excited with the myriad of additional warm-water fossil molluscs that were being added to New Zealand’s known Pliocene fauna and he had intended to describe and name a number of the new species.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article and the specimens are lodged in the collections of Auckland War Memorial Museum.

Additional information

Funding

Watercare funded the work by TFS and NC. Auckland War Memorial Museum supported WB and the work by TFS and NC. BWH and AGB received no funding support.