Burgess Shale fossils illustrate the origin of the mandibulate body plan
Nature
545(7652): 89-92
Publication
Supplementary file including systematic paleontology section is at https://static-content.springer.com/esm/art%3A10.1038%2Fnature22080/MediaObjects/41586_2017_BFnature22080_MOESM1_ESM.pdf