Natural History Museum Luxembourg, Department of Paleontology, 25 rue Mnster, 2160 Luxembourg City, Luxembourg..
Department of Geosciences, Smith College, Northampton, MA 01063, USA..
Zootaxa. 2021 Nov 24;5071(3):369-383. doi: 10.11646/zootaxa.5071.3.4.
The Lower Triassic fossil record of brittle stars is relatively rich, yet most records published to date are based on poorly preserved or insufficiently known fossils. This hampers exhaustive morphological analyses, comparison with recent relatives or inclusion of Early Triassic ophiuroid taxa in phylogenetic estimates. Here, we describe a new ophiuroid from the Lower Triassic of Nevada, preserved as phosphatized skeletal parts and assigned to the new taxon Ophiosuperstes praeparvus gen. et sp. nov Maxwell, V. Pruss. S.B. This unusual preservation of the fossils allowed for acid-extraction of an entire suite of dissociated skeletal parts, including lateral arm plates, ventral arm plates, vertebrae and various disk plates, thus unlocking sufficient morphological information to explore the phylogenetic position of the new taxon. Bayesian phylogenetic inference suggests a basalmost position of O. praeparvus within the Ophintegrida, sister to all other sampled members of that superorder. The existence of coeval but more derived ophiuroids suggests that O. praeparvus probably represents a member of a more ancient stem ophintegrid group persisting into the Early Triassic.
下三叠统海星的化石记录相对丰富，但迄今为止发表的大多数记录都是基于保存不佳或知之甚少的化石。这阻碍了详尽的形态分析、与现代近亲的比较或在系统发育估计中纳入早三叠世蛇尾类群。在这里，我们描述了一种来自内华达州下三叠统的新型蛇尾类，保存在磷质骨骼部分中，并被指定为新分类群 Ophiosuperstes praeparvus gen. et sp. nov Maxwell, V. Pruss. S.B. 这种不寻常的化石保存方式允许对一整套分离的骨骼部分进行酸提取，包括侧臂板、腹臂板、脊椎和各种盘状板，从而解锁了足够的形态信息来探索新分类群的系统发育位置。贝叶斯系统发育推断表明，O. praeparvus 在 Ophintegrida 中处于最基础的位置，是该超目所有其他采样成员的姐妹群。同时存在同时代但更衍生的蛇尾类群表明，O. praeparvus 可能代表一个更古老的蛇尾类群的成员，在早三叠世仍然存在。
