Other
Black Hills Institute of Geological Research, Inc.: Ammonoids
Ammonoids, more commonly referred to as Ammonites, are the extinct ancestors of today's octopus, squid and nautilus. This page provides excellent information about these creatures, as well as diagrams and pictures.
Smithsonian Institution
National Museum of Natural History: Paleobiology: Green River Fossil Collections
Search the collection of 35,000 fossiliferous rocks found within the Green River Formation of Colorado and Utah. View some of these 50 million year old insect fossils in a linked slide show.
Smithsonian Institution
National Museum of Natural History: Paleobiology: Green River Insects
Interactive photo search of the collection of 35,000 fossiliferous rocks found within the Green River Formation of Colorado and Utah.
Indiana University
Indiana Univ. Bloomington: Geo Notes: Crinoids: Ancient Versus Modern Forms [Pdf]
Presents some facts about crinoids, a marine animal abundant during the Paleozoic Era, with many fossil species present in Indiana. This animal can still be found in the Caribbean Sea today.