The Paleontology of North America

Hemichordates and Chordates from North America

See images from the:

Monograptus priodon From the Silurian in California © 2004 UCMP	Orthograptus From the Ordovician in West Virginia © 2003 Thomas Kammer	Graptolites From the Ordovician in New Jersey © 2003 Otto S. Zapecza
Dictyonema From the Devonian in New York © 2000 Karl Wilson