近期《自然》期刊发表了一项研究，发现螯肢亚门（其下包括蜘蛛及蝎子）的神经系统与已灭绝的大附肢纲（头部伸出可怕呈爪状肢体的古代生物）最相似。
大附肢纲属已绝灭节肢动物，拥有现代动物没有的庞大呈爪状肢体，其进化历程一直备受争议。中国昆明云南大学侯先光教授、美国亚利桑那大学Nicholas Strausfeld教授与他们的团队发现了一副保存完好，属于中国5.2亿年前早寒武世时期的大附肢动物化石。他们重塑出此动物的神经系统，包括头部和躯干的神经分节，这神经系统是目前为止最完整的寒武世动物的神经系统。结果表明，大附肢纲酷似螯肢亚门，其下包括蜘蛛、蝎子及他们的近亲。(生物谷Bioon.com)
生物谷推荐的英文摘要
Nature doi:10.1038/nature12520
Chelicerate neural ground pattern in a Cambrian great appendage arthropod
Gengo Tanaka,Xianguang Hou,Xiaoya Ma,Gregory D. Edgecombe& Nicholas J. Strausfeld
Preservation of neural tissue in early Cambrian arthropods has recently been demonstrated, to a degree that segmental structures of the head can be associated with individual brain neuromeres. This association provides novel data for addressing long-standing controversies about the segmental identities of specialized head appendages in fossil taxa. Here we document neuroanatomy in the head and trunk of a ‘great appendage’ arthropod, Alalcomenaeus sp., from the Chengjiang biota, southwest China, providing the most complete neuroanatomical profile known from a Cambrian animal. Micro-computed tomography reveals a configuration of one optic neuropil separate from a protocerebrum contiguous with four head ganglia, succeeded by eight contiguous ganglia in an eleven-segment trunk. Arrangements of optic neuropils, the brain and ganglia correspond most closely to the nervous system of Chelicerata of all extant arthropods, supporting the assignment of ‘great appendage’ arthropods to the chelicerate total group. The position of the deutocerebral neuromere aligns with the insertion of the great appendage, indicating its deutocerebral innervation and corroborating a homology between the ‘great appendage’ and chelicera indicated by morphological similarities. Alalcomenaeus and Fuxianhuia protensa demonstrate that the two main configurations of the brain observed in modern arthropods, those of Chelicerata and Mandibulata, respectively, had evolved by the early Cambrian.
