title: Fuxianhuiid ventral nerve cord and early nervous system evolution in Panarthropoda.
abstract: Panarthropods are typified by disparate grades of neurological organization reflecting a complex evolutionary history. The fossil record offers a unique opportunity to reconstruct early character evolution of the nervous system via exceptional preservation in extinct representatives. Here we describe the neurological architecture of the ventral nerve cord (VNC) in the upper-stem group euarthropod Chengjiangocaris kunmingensis from the early Cambrian Xiaoshiba Lagerstätte (South China). The VNC of C. kunmingensis comprises a homonymous series of condensed ganglia that extend throughout the body, each associated with a pair of biramous limbs. Submillimetric preservation reveals numerous segmental and intersegmental nerve roots emerging from both sides of the VNC, which correspond topologically to the peripheral nerves of extant Priapulida and Onychophora. The fuxianhuiid VNC indicates that ancestral neurological features of Ecdysozoa persisted into derived members of stem-group Euarthropoda but were later lost in crown-group representatives. These findings illuminate the VNC ground pattern in Panarthropoda and suggest the independent secondary loss of cycloneuralian-like neurological characters in Tardigrada and Euarthropoda.
authors.affiliation: Yunnan Key Laboratory for Paleobiology, Yunnan University, Kunming 650091, China;
authors.forename: Jie
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, United Kingdom;
authors.forename: Javier
authors.initials: J
authors.lastname: Ortega-Hernández
authors.affiliation: Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, United Kingdom;
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Butterfield
authors.affiliation: Yunnan Key Laboratory for Paleobiology, Yunnan University, Kunming 650091, China; Developmental Neurobiology Group, Biocenter, Ludwig-Maximilians-Universität, 82152 Martinsried, Germany; GeoBio-Center Ludwig-Maximilians-Universität, Munich 80333, Germany;
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Developmental Neurobiology Group, Biocenter, Ludwig-Maximilians-Universität, 82152 Martinsried, Germany;
authors.forename: George S
authors.initials: GS
authors.lastname: Boyan
authors.affiliation: Yunnan Key Laboratory for Paleobiology, Yunnan University, Kunming 650091, China;
authors.forename: Jin-Bo
authors.initials: JB
authors.lastname: Hou
authors.affiliation: College of Resources and Environmental Engineering, Guizhou University, Guiyang 550003, China.
authors.forename: Tian
authors.initials: T
authors.lastname: Lan
authors.affiliation: Yunnan Key Laboratory for Paleobiology, Yunnan University, Kunming 650091, China; xgzhang@ynu.edu.cn.
authors.forename: Xi-Guang
authors.initials: XG
authors.lastname: Zhang
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002681:China; D005580:Fossils; D017952:Ganglia, Invertebrate / Q000033:anatomy & histology; D009420:Nervous System / Q000033:anatomy & histology*; D010802:Phylogeny; D013045:Species Specificity; D058467:Tardigrada / Q000033:anatomy & histology*
keywords: Cambrian Explosion; Onychophora; Xiaoshiba Lagerstätte; phylogeny; stem-group Euarthropoda