MEI Shi - long , 1991 . Middle and Late Cambrian conodont and trilobite biostratigraphy in Wanxian, Hebei . Unpublished Ph. D thesis of Peking University.
1. tiny fossil cone-shaped tooth of the most primitive vertebrate: the conodont
2. small (2 in) extinct eellike fish with a finned tail and a notochord and having cone-shaped teeth containing cellular bone; late Cambrian to late Triassic; possible predecessor of the cyclostomes
