New look at ammonoid taphonomy, based on field experiments with modern chambered nautilus

Research Article| November 01, 2005 New look at ammonoid taphonomy, based on field experiments with modern chambered nautilus Ryoji Wani; Ryoji Wani 1 Department of Geology, National Science Museum, 3-23-1 Hyakunincho, Shinjuku-ku, Tokyo 169-0073, Japan Search for other works by this author on: GSW Google Scholar Tomoki Kase; Tomoki Kase 1 Department of Geology, National Science Museum, 3-23-1 Hyakunincho, Shinjuku-ku, Tokyo 169-0073, Japan Search for other works by this author on: GSW Google Scholar Yasunari Shigeta; Yasunari Shigeta 1 Department of Geology, National Science Museum, 3-23-1 Hyakunincho, Shinjuku-ku, Tokyo 169-0073, Japan Search for other works by this author on: GSW Google Scholar Roberto De Ocampo Roberto De Ocampo 2Geology Division, National Museum of the Philippines, P. Burgos Street, Manila 1000, Philippines Search for other works by this author on: GSW Google Scholar Author and Article Information Ryoji Wani 1 Department of Geology, National Science Museum, 3-23-1 Hyakunincho, Shinjuku-ku, Tokyo 169-0073, Japan Tomoki Kase 1 Department of Geology, National Science Museum, 3-23-1 Hyakunincho, Shinjuku-ku, Tokyo 169-0073, Japan Yasunari Shigeta 1 Department of Geology, National Science Museum, 3-23-1 Hyakunincho, Shinjuku-ku, Tokyo 169-0073, Japan Roberto De Ocampo 2Geology Division, National Museum of the Philippines, P. Burgos Street, Manila 1000, Philippines Publisher: Geological Society of America Received: 11 Mar 2005 Revision Received: 22 Jun 2005 Accepted: 28 Jun 2005 First Online: 02 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2005) 33 (11): 849–852. https://doi.org/10.1130/G21712.1 Article history Received: 11 Mar 2005 Revision Received: 22 Jun 2005 Accepted: 28 Jun 2005 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Ryoji Wani, Tomoki Kase, Yasunari Shigeta, Roberto De Ocampo; New look at ammonoid taphonomy, based on field experiments with modern chambered nautilus. Geology 2005;; 33 (11): 849–852. doi: https://doi.org/10.1130/G21712.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Field experiments with Nautilus pompilius in the Philippines have uncovered two previously unknown postmortem phenomena: (1) waterlogging of the phragmocone does not occur until the mantle tissue detaches from the shell due to decomposition, and (2) the phragmocones of empty shells flood with seawater rapidly due to low internal gas pressure (<0.9 atm). The latter is more significant for small shells, because of the lower total gas pressure in their phragmocones compared to larger shells, and the smaller limit of seawater volume that still allows flotation. The limiting diameter for shells to sink from only the latter mechanism (lower internal gas pressure) is ∼200 mm. Ammonoids generally have body chambers longer than N. pompilius, but the ratio of body chamber volume to phragmocone volume for most ammonoids is the same as for N. pompilius. This ratio is the determining factor that allowed ammonoid shells either to float or sink from pressure compensation alone. This strongly suggests that (1) their limiting shell diameters approximate that of N. pompilius (i.e., ∼200 mm), (2) such shells sank rapidly close to their habitats, even if they initially floated, and (3) only large shells had the potential to drift postmortem over long distances. These findings are crucial to interpreting the early taphonomic history of extinct ammonoids. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.