Devonian age strata exposed in east-central Iowa preserve coral-rich biostromes and bioherms. Preservation of these fossils is highly variable, suggesting fundamental differences in the conditions under which these assemblages accumulated. We have further explored this issue by comparing differences in preservation exhibited by common Devonian corals (Hexagonaria sp. Favosites sp. and Zaphrentis sp.) collected from a bioherm preserved in the Solon Member of the Little Cedar Formation. The same taxa were collected from the stratigraphically higher Rapid Member of the Little Cedar Formation exposed at a different locality.
††† Species were removed and analyzed for a variety of physical and biological attributes, including abrasion, bioerosion, and fragmentation. Comparison of taphonomic characteristics exhibited by corals between bioherms and biostromes, as well as between corals preserved in the Rapid and Solon members suggest two different types of preservation exhibited on similar taxa. Corals collected from the Solon bioherm show little evidence of abrasion, encrusting and boring suggesting that they were removed from the taphonomicilly active zone (TAZ) by rapid burial while still alive or by reef succession. Corals collected from the Rapid member biostrome showed significant abrasion and fragmentation, but very little encrustation and boring. This suggests that the biostrome accumulated largely by physical process and was subsequently buried rapidly.
James Levingston, ’00 Salem, MO
Majors: Physics and Geology
Sponsor: Benjamin Greenstein