ABSTRACT

Cidaroid sea urchin remains (isolated radioles and rare plates) are described from marine strata of the Harnetts Formation (New Zealand Waitakian Stage (=Late Chattian – Early Aquitarian)), part of the Otaua Group (Late Oligocene – Early Miocene) outcropping in the Waimamaku Valley, in the South Hokianga district, Northland, New Zealand. Abundant large and robust spines (radioles), assigned here to two previously known Indo-Pacific genera Stereocidaris and Phyllacanthus, form part of a distinctive, transported shallow shelf component of a macrofossil assemblage occurring in grit horizons within the deep marine (bathyal) sandstone sequence. Cidaroid spine morphology allows for tentative identification of fossil taxa to species level. Several test fragments, namely large but worn interambulacral plates, have also been collected from the type locality and a possible nearby outlier of Harnetts Formation. These outcrops are locally significant as the only known exposures of the geographically restricted unit, incorporated into the Northland Allochthon during its emplacement.

摘要

Cidaroid 海胆遗骸（孤立的放射线和稀有板块）来自 Harnetts 地层（新西兰怀塔基阶（=晚查特阶 - 早海基阶））的海相地层，Otaua 群（晚渐新世 - 早中新世）的一部分在Waimamaku 山谷，位于新西兰北部地区的南霍基安加区。大量大而健壮的刺（radioles），在这里分配给两个以前已知的印度太平洋属Stereocidaris和Phyllacanthus，形成发生在深海（深海）砂岩序列内的砂砾层中的大型化石组合的独特的、运输的浅层陆架组分的一部分。Cidaroid 脊柱形态允许将化石类群初步鉴定到物种水平。几个测试碎片，即大而磨损的 interambural plates，也从模式产地和 Harnetts 组附近可能的离群点收集到。这些露头在当地具有重要意义，因为地理上受限的单位唯一已知的暴露，在其进驻期间并入 Northland Allochthon。