Recently in the process of experiment on limestones from the Cedar Valley formation near Iowa City, Iowa, 0.5 n. hydrochloric acid was used to decompose the carbonates present. In the residues obtained by filtration and washing of the resulting product there were discovered some organic remains almost microscopic in size which were very similar in appearance to those of the jaws of certain groups of recent marine annelids. Further investigations revealed several complete specimens and a number of fragments which show that these remains probably are distributed quite generally through the Cedar Valley limestones. They are now known to occur not only at the horizon of the first discovery but also somewhat higher in position in the same locality and at a different horizon at Mid River several miles up Iowa River.
Proceedings of the Iowa Academy of Science
©1923 Iowa Academy of Science, Inc.
Searight, Walter V.
"Fossil Annelid Jaws from the Iowa Devonian,"
Proceedings of the Iowa Academy of Science, 30(1), 433-436.
Available at: https://scholarworks.uni.edu/pias/vol30/iss1/69