[homology-note] "(...) at some stage of its development, every chordate exhibits five uniquely derived characters or synapomorphies of the group: (...) (4) a single, tubular nerve cord that is located dorsal to the notochord (...).[well established][VHOG]" xsd:string {date_retrieved="2012-09-17", external_class="VHOG:0001384", ontology="VHOG", source="ISBN:978-0030223693 Liem KF, Bemis WE, Walker WF, Grande L, Functional Anatomy of the Vertebrates: An Evolutionary Perspective (2001) p.28", source="http://bgee.unil.ch/"}