The New ZealandZoophycosrevisited: Morphology, ethology, and paleoecology

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Abstract
Large, well‐preserved Zoophycos specimens are abundant and widespread in the Amuri Limestone Group (Upper Cretaceous‐lower Oligocene) on the South Island of New Zealand. Although several previous workers have offered detailed descriptions of Zoophycos in the group, their hypotheses concerning its mode of production have flaws. We propose a new ethologic explanation of Zoophycos that avoids pitfalls of previously published explanations. The Amuri Zoophycos represents a complex spreite of spreites (= spreiten), which consists of a spiralled set of numerous, overlapping, protrusive, Rhizocorallium‐like spreite tongues. These tongues are repetitive excavations produced by an infaunal deposit feeder probing progressively downward and outward in the sediment. The causative burrow is a U‐shaped tube that evidently was produced for circulating oxygenated water in the burrow while the burrower fed within the sediment. The complete Zoophycos structure is a composite burrow system of many overlapping U‐shaped burrows, only one of which was inhabited by the Zoophycos progenitor at any given time. Each Rhizocorallium‐like spreite tongue is mainly protrusive; but the entire Zoophycos system is retrusive, because the earliest spreite tongues were emplaced deep in the sediment and subsequent spreite tongues were added in an upward spiral.

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