Andy Rich ‘20 Investigates Taphonomy and Biodiversity of Fish Fossils from the Middle Devonian Milwaukee Formation
Andy Rich ’20 sought to fill in the knowledge gap around the poorly exposed Milwaukee Formation by analyzing the taphonomic and taxonomic features of the fish fauna curated in the museum collections. Andy’s advisor was Jay Zambito.
The Devonian Milwaukee Formation dolostone crops out in a single exposure along the Milwaukee River in the City of Milwaukee. Fossils from this unit were originally discovered by quarry workers who were excavating the argillaceous dolostone for the Milwaukee Cement Company, but most of the original quarry is now covered. The Milwaukee Formation is rich in both invertebrate and vertebrate fossils. Vertebrate fossils are entirely fish remains and include Sarcopterygii, Chondrichthyes, and Placodermi. This study aims to decipher the biodiversity of the Milwaukee Formation based on the fossil assemblage composition and to reconstruct the depositional environment through taphonomic analysis.
This research project began by accessing the collections of the Milwaukee Public Museum and the University of Wisconsin - Milwaukee. All of the fish fossils from the Milwaukee Formation of both collections were compiled into a comprehensive data set that looks at the taphonomic and taxonomic features of each fossil specimen. This data set is composed of 675 specimens. Preliminary taxonomic analysis indicates placoderms dominated the fauna, and taphonomic study shows the environment of deposition likely had low background energy that was periodically disturbed by storms.