Data from: A new crustacean from the Herefordshire (Silurian) Lagerstätte, UK, and its significance in malacostracan evolution

Cascolus ravitis gen. et sp. nov. is a three-dimensionally preserved fossil crustacean with soft parts from the Herefordshire (Silurian) Lagerstätte, UK. It is characterized by a head with a head shield and five limb pairs, and a thorax (pereon) with nine appendage-bearing segments followed by an apodous abdomen (pleon). All the appendages except the first are biramous and have a gnathobase. The post-mandibular appendages are similar one to another, and bear petal-shaped epipods that probably functioned as a part of the respiratory–circulatory system. Cladistic analysis resolves the new taxon as a stem-group leptostracan (Malacostraca). This well-preserved arthropod provides novel insights into the evolution of appendage morphology, tagmosis and the possible respiratory–circulatory physiology of a basal malacostracan.

卡斯库拉斯·拉维蒂（Cascolus ravitis）新属新种（gen. et sp. nov.）是一种产自英国赫里福德（志留纪）特异埋藏化石库（Lagerstätte）、保存有软躯体结构的三维甲壳类化石。该类群具有带头甲与5对附肢的头部，以及由9个具附肢体节构成的胸部（胸节区，pereon），其后接续无附肢的腹部（腹节区，pleon）。除第一对附肢外，其余附肢均为双枝型，且具有颚基（gnathobase）。大颚后的附肢形态均一，且生有花瓣状上肢（epipods），该结构可能作为呼吸-循环系统的组成部分行使功能。支序分类分析（cladistic analysis）结果显示，这一新类群隶属于软甲纲（Malacostraca）薄甲目（Leptostraca）的干群（stem-group）类群。这一保存完好的节肢动物，为基干软甲类（basal malacostracan）的附肢形态演化、体区分化（tagmosis）以及潜在的呼吸-循环生理学机制提供了全新的研究视角。