Contents

29 May 1992
Vol 256, Issue 5061

About The Cover

Photomicrograph of a longitudinal section through an element of the conodont Cordylodus showing features that imply that conodonts have a vertebrate affinity. The light-colored birefringent crown is interpreted as cellular bone and the spherules in dark basal filling as calcified cartilage. Cordylodus was extant from the late Cambrian to earliest Ordovician. See page 1308 and the Perspective on page 1285. (Background) Photograph of the soft-bodied specimen of the conodont Clydagnathus (Mississippian) discovered in 1982 in Edinburgh, Scotland. [Photomicrograph: I. J. Sansom; photograph: J. K. Ingham]