Scales of thelodont and shark-like fishes from the Ordovician of Colorado

Ivan J. Sansom*, Moya M. Smith, M. Paul Smith

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

102 Citations (Scopus)


THE phylogeny of primitive vertebrates has been investigated over the past fifteen years1-3, and there has been a notable increase in the amount of data by which such phylogenies can be tested4-7. Stratigraphic data should provide constraints to such analyses, and we record here descriptions of putative shark and thelodont scales from the Harding Sandstone (Caradoc, Late Ordovician) of Colorado. The fossil record of sharks is extended back from the Llandovery (lower Silurian) by some 25 million years and that of thelodonts by 10 million years from the Ashgill (Late Ordovician). The new data indicate that a major radiation of lower vertebrates took place during the Ordovician.

Original languageEnglish
Pages (from-to)628-630
Number of pages3
Issue number6566
Publication statusPublished - 15 Feb 1996

ASJC Scopus subject areas

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