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Science 10 July 1987:
Vol. 237. no. 4811, pp. 190 - 192
DOI: 10.1126/science.237.4811.190
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Articles

A Reassessment of Astraspis desiderata, the Oldest North American Vertebrate

DAVID K. ELLIOTT 1

1 Department of Geology, Northern Arizona University, Flagstaff, AZ 86011.

The fossil evidence for the early evolution of vertebrates consists of the remains of agnathans, jawless vertebrates, from the Ordovician of Australia, North America, and Bolivia. Because of the fragmentary nature of the material, it has not been possible to reconstruct these animals sufficiently well to understand their relation to each other and to later vertebrates. Though two genera have been known from the Harding Sandstone of North America since 1892, there are still only three articulated specimens known, two of Astraspis desiderata and one of Eriptychius americanus. The most recently found specimen of Astraspis was reexamined and found to show the orbit, a series of eight branchial openings and a complete tail, structures hitherto undescribed in any Ordovician vertebrate. A reconstruction ofAstraspis shows, on the basis of the series of branchial openings, that it is a primitive craniate and not a heterostracan as previously thought.

Submitted on March 19, 1987
Accepted on June 3, 1987


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
The Sequence Stratigraphic and Environmental Context of Primitive Vertebrates: Harding Sandstone, Upper Ordovician, Colorado, USA.
J. L. ALLULEE and S. M. HOLLAND (2005)
Palaios 20, 518-533
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