A unique, large-sized stem-Odonata (Insecta) found in the early Pennsylvanian of New Brunswick (Canada)

A stem-relative of dragon- and damselflies, Brunellopteron norradi Béthoux, Deregnaucourt and Norrad gen. et spec. nov., is documented based on a specimen found at Robertson Point (Grand Lake, New Brunswick, Canada; Sunburry Creek Formation; early Moscovian, Pennsylvanian) and preserving the basal half of a hindwing. A comparative analysis of the evolution of wing venation in early odonates demonstrates that it belongs to a yet poorly documented subset of species. Specifically, it displays a MP+CuA fusion, a CuA+CuP fusion, and a CuP+AA fusion, but lacks the ‘extended’ MP+Cu/CuA fusion and the ‘extended’ (CuP/CuA+CuP)+AA fusion which occurrence is typical of most Odonata, including Meganeura-like species. The occurrence of intercalary veins suggests that its closest relative might be Gallotypus oudardi Nel, Garrouste and Roques, 2008, from the Moscovian of northern France.

Methods
The two reflectance transformation imaging (RTI) files provided in this dataset document the specimen NBMG 21589, deposited at the New Brunswick Museum (Palaeontology collection; Saint John, New Brunswick, Canada). Each RTI file was generated using 42 photographs, themselves taken using a ca. 30-cm diameter automated light dome driving a digital camera Canon EOS 5D Mark III coupled to a Canon MP-E 65 mm macro lens (Canon, Tokyo, Japan) . Original photographs were optimized using Adobe Photoshop CS6 (Adobe Systems, San Jose, CA, USA) before RTI-processing, itself achieved using the RTIbuilder software (Cultural Heritage Imaging).

本研究基于在加拿大新不伦瑞克省格兰德湖罗伯逊点（孙伯里溪组，宾夕法尼亚纪莫斯科阶早期）发现的一枚保存有后翅基部半段的标本，对蜻蜓与豆娘的基干类群新属新种Brunellopteron norradi Béthoux、Deregnaucourt及Norrad进行了正式记述。通过对早期蜻蜓目昆虫翅脉演化的比较分析，可知该种隶属于一类迄今研究报道尚少的类群。具体而言，该种具有MP+CuA融合、CuA+CuP融合以及CuP+AA融合的特征，但缺失“延伸型”MP+Cu/CuA融合与“延伸型”(CuP/CuA+CuP)+AA融合——后者为多数蜻蜓目昆虫（包括巨脉蜻蜓类群）的典型特征。其具闰脉的特征表明，该种的近缘类群可能是产自法国北部莫斯科阶地层的Gallotypus oudardi Nel、Garrouste及Roques, 2008。

方法
本数据集附带的两份反射变换成像（reflectance transformation imaging, RTI）文件，对应保存于加拿大新不伦瑞克省圣约翰市新不伦瑞克博物馆古生物馆藏的标本NBMG 21589。每份RTI文件均由42张照片合成：这些照片通过直径约30厘米的自动光照穹顶，搭载搭配佳能MP-E 65mm微距镜头（日本东京佳能公司）的佳能EOS 5D Mark III数码相机拍摄完成。在进行RTI处理前，原始照片已通过Adobe Photoshop CS6（美国加利福尼亚州圣何塞奥多比系统公司）完成优化，RTI处理则采用RTIbuilder软件（文化遗产成像项目组）完成。