Two new isocrinids are described from the Lower Cretaceous Agrio Formation of the Neuquén Basin, west-central Argentina. Isocrinus (Chladocrinus) covuncoensis new species is based on several beautifully preserved specimens from Valanginian beds of the Pilmatué Member. It is characterized by a small size, multiramose crown with six arm divisions, 240 arm tips, mostly isotomous branching, seven (or rarely eight) secundibrachials, smooth and stout column, short noditaxis, and pentalobate columnals. The species occurs in a 30 m thick interval of cross-bedded sandstones and mixed clastic-carbonate sediments that represent the migration of large, tidally influenced, subaqueous dunes developed in the offshore. Sudden burial of crinoids that dwelled on the dune toes and interdunes, possibly by the acceleration of the lee face migration, provided the exceptional preservation of specimens and thus this finding can be considered as a local crinoid Konservat Lagerstätte. Isocrinus (Chladocrinus) pehuenchensis new species is described from a single articulated specimen preserved in a silty calcareous concretion collected from a late Hauterivian concretion level of the Agua de la Mula Member. It is characterized by isotomous branching, eight or nine secundibrachials (IIBr), slender column ornamented with medial ridge of fine tubercles, interradius acuminated with fine tubercles on its tip, short noditaxis, and pentastellate columnals. It is associated with low-energy fall-out deposits in the offshore. The excellent state of preservation was due to an early cementation process by carbonate that enhanced lithification around the specimen.UUID: http://zoobank.org/4763ae70-9d0a-4015-b1c9-6a7ceeedfb1a

中文翻译：

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南美洲中生代第一个铰接有茎的海百合：阿根廷中西部内乌肯盆地下白垩统的两个新物种

在阿根廷中西部的内乌肯盆地的下白垩统 Agrio 组中描述了两个新的 isocrinids。等角(角鲨属)柑桔新物种是基于来自皮尔马图成员瓦朗吉尼河床的几个保存完好的标本。它的特点是体积小，多枝冠，有六个臂部，240 个臂尖，大部分是等分枝，七个（或很少八个）第二臂，光滑而粗壮的柱，短节节和五叶柱。该物种出现在 30 m 厚的交叉层状砂岩和混合碎屑碳酸盐沉积物中，这些沉积物代表了近海发育的大型、受潮汐影响的水下沙丘的迁移。居住在沙丘脚趾和沙丘间的海百合的突然埋葬，可能是由于背风面迁移的加速，提供了标本的特殊保存，因此这一发现可以被认为是当地的海百合 Konservat Lagerstätte。等角(角鲨属)大黄蜂新物种是从保存在粉质钙质结核中的单个关节标本中描述的，该标本收集自 Agua de la Mula 成员的晚期 Hauterivian 结核水平。其特征是等分枝，八或九个第二臂（IIBr），细长的柱状体，内侧有细小瘤脊，桡骨间渐尖，顶端有细小瘤，节节短，呈五星状柱状。它与近海的低能量沉降沉积物有关。良好的保存状态是由于碳酸盐的早期胶结过程增强了标本周围的岩化。UUID：http://zoobank.org/4763ae70-9d0a-4015-b1c9-6a7ceeedfb1a