Date of Degree
PhD (Doctor of Philosophy)
Christopher A. Brochu
The Jasper Hiemstra limestone quarry outside of Delta, Iowa, preserves an aquatic and terrestrial fauna from the Late Mississippian of Midwestern North America. Stratigraphic and paleontological data demonstrate that the quarry correlates with the Ste. Genevieve Formation, approximately 330 million years (Ma) ago. The site formed in a karst terrain with at most minor marine influence. Numerous invertebrate and as-yet undefined vertebrate taxa are preserved. Three new vertebrate taxa are described here for the first time. Eustreptogyracanthus iaspius is a gyracanth gnathostome that possesses unique sculpturing on the pectoral fins. It is associated with scales and elements of the pectoral girdle, similar to those seen elsewhere in the group. Floydus punicellus is a rhizodontid sarcopterygian that possesses a partially ossified brain case, enlarged pelvis, sculptured underside to the postparietals and anteroposterior lateral line enervation of the postparietals and supratemporals. Aliuslater inmuri is an actinopterygian that possesses an unusual upper jaw. Previous workers have found evidence for a consistant tetrapod province around the world over a period of time that includes the Hiemstra Quarry's deposition, but the present analysis does not find strong support for this hypothesis.
Ste. Genevieve Formation, St. Louis Formation, Actinopterygii, Rhizodontida, Gyracanthida
xiii, 161 pages
Includes bibliographical references (pages 152-161).
Copyright 2006 Daniel Snyder