In view of the exceptional stratigraphic value of Late Carboniferous ammonoids, it seems worthwhile to bring together the available information in regard to the known occurrences of these fossils in our State. However, they are rare indeed here, in comparison with the regions to the south, in spite of the fact that marine beds of Pennsylvanian age are widespread in the southern and central portions of Iowa. Their dearth in this area is presumably due to an abnormal salinity of the waters in which the sediments accumulated, rather than to a land barrier. Altogether I have been able to locate only half-a-dozen specimens from our Pennsylvanian strata. These came from four localities, and they represent only three species.
Proceedings of the Iowa Academy of Science
©1949 Iowa Academy of Science, Inc.
Miller, A. K.
"Iowa Pennsylvanian Goniatites,"
Proceedings of the Iowa Academy of Science, 56(1), 225-228.
Available at: https://scholarworks.uni.edu/pias/vol56/iss1/29