Nature 380, 702 - 704 (25 April 1996); doi:10.1038/380702a0

Histology of the first fish

M. P. Smith^*, I. J. Sansom^* & J. E. Repetski^†

^*School of Earth Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
^†US Geological Survey, MS 970, National Center, Reston, Virginia 22092, USA

THE first description of Anatolepis Bockelie & Fortey was from early Ordovician sediments of Ny Friesland, Spitsbergen^1,2, but the genus is now known from many localities in North America and Greenland, ranging in age from the Late Cambrian period to the Early Ordovician^3–6. Although initially interpreted as an agnathan fish^2,3 that predated other representatives⁷, this has been widely disputed because the available histological data were unconvincing^6,8–10 and the scales fell outside the known morpho-logical range of other accepted early vertebrates^9–11. Further doubt was cast upon the vertebrate affinity of Anatolepis when specimens from East Greenland were interpreted as the cuticular fragments of aglaspid arthropods⁶, although this interpretation has also been refuted¹². Here we report on the morphology and histology of large collections of Anatolepis, and demonstrate the presence of dentine, a tissue unique to vertebrates, confirming that the taxon is both a vertebrate and the oldest known fish.

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