跳蚤作为重要的病媒昆虫，对人类健康和家畜生产造成很大的危害。因化石材料稀少，人们对跳蚤的起源及早期演化知之甚少，学者们对中生代蚤类的分类位置也争议很大。本项目将基于我国东北中生代晚期侏罗纪（距今约1.65亿年）和白垩纪（距今约1.25亿年）采集的蚤类化石标本，着重开展形态学、分类学和系统学研究。从历史演化的角度，对蚤类特殊的结构（如刺吸式口器、外生殖器、刚毛分布、触角等）进行细致的功能形态分析，探索蚤类与宿主的协同演化关系；结合现生跳蚤的形态特征数据，利用团队收藏的长翅目、膜翅目等全变态昆虫化石材料，开展系统发育分析，揭开蚤目的系统发育关系和历史演化过程，探索蚤目的起源和分化时间节点。为恢复和重建蚤目的自然演化历史提供证据。

Fleas, as important insect vectors, are harmful to human’s health and livestock production. Due to scarce fossil materials, the origin and early evolution of fleas are still not clear, and entomologists have different views about the taxonomy and phylogenetic positions of Mesozoic fleas. Based on flea fossils collected from the Middle Jurassic (about 165 Mya) and Early Cretaceous (about 125 Mya) of northeastern China, the proposed research will focus on the morphology, systematics and phylogeny analyses of Siphonaptera. We will carry out functional morphology analyses of some special structures of fleas, such as sucking mouthparts, external genitals, setae, antenna, etc., and explore the co-evolutionary relationships between fleas and their hosts. Compared with the morphological characters of extant fleas, together with the features of abundant holometabolous insect fossils, such as scorpionflies and wasps in our collections, we plan to conduct phylogenetic analyses, demonstrate fleas’ phylogenetic relationships and historical evolutional process, and search for the origin and diversified time nodes of Siphonaptera. The results will provide evidences for elucidation and reconstruction the natural history of Siphonaptera.