The Preservation of Body Tissues, Shell, and Mandibles in the Ceratitid Ammonoid Austrotrachyceras (Late Triassic), Austria

Ammonoid Habitats and Life History

“…Shell-wall duplication was interpreted by Birkelund (1981) in Gaudryceras as indication that its juvenile shell was exceptionally covered by the mantle. Additionally, in situ fossil buccal masses are commonly located near the centre of the body chamber, supporting a jaw-function rather than an operculum-function (Schindewolf 1958;Lehmann 1976Lehmann , 1980Lehmann , 1988Kennedy and Cobban 1976;Tanabe 1983;Morton and Nixon 1987;Tanabe and Fukuda 1987;Mapes 1987;Bandel 1988;Nixon 1988Nixon , 1996Seilacher 1993;Westermann 1996;Kennedy et al 2002;Wippich and Lehmann 2004;Doguzhaeva et al 2007;Keupp 2007;Landman et al 2007b. As shown by Wani (2007), in situ preservation of buccal masses in the body chamber of ammonoids coincides with the in situ deposition of the ammonoid shell itself (Chamberlain et al 1981;Wani et al 2005).…”

“…The cephalopod/aptychi ratio provides a useful criterion to evaluate the postmortem transport of ammonoids (Olóriz et al 1996;Lukeneder and Tanabe 2002;Reboulet et al 2003;Doguzhaeva et al 2007;Schlögl et al 2011). Accumulated ammonoid shells can be affected by resedimentation processes generating fragmentation ( sensu Fernández-López 1991Fernández-López andMeléndez 1994, 1995;Olóriz et al 1996;Fernández-López et al 1999;Landman and Klofak 2012).…”

The Body Chamber Length Variations and Muscle and Mantle Attachments in Ammonoids

“…Lack of phosphorus in the mantle matter and in the mandibles reveals that the preservation of the non-biomineralized soft tissue was not controlled by a phosphorus-rich medium. Contrary to the mantle and mandibles, the shell wall in Austrotrachyceras is calcareous; it is composed of O (65-80 %), C (25 %), Ca (8-16 %), Sb (2 %), Mo (2 %), Mg, K (each 1 %), and S, Si, Mn, Fe (each < 1 %) (Doguzhaeva et al , 2007b. The low oxygen depositional environment (Griffith 1977) responsible for carbonization of the mantle and the mandibles of Austrotrachyceras also favored the preservation of the muscular mantle, ink sacs and arm-hooks of the coleoid Phragmoteuthis bisinuata (Doguzhaeva et al 2007b, Doguzhaeva andSummesberger 2012).…”

Exploration of the Oxynoticeratidae ornamental morphospace using the discrete cosine transform (DCT) to analyze rib patterns

“…Test of hypothesis 4.-This hypothesis is currently not test− able because it requires soft−tissue preservation, which is rare in ammonoids and only occurs in exceptional preservational conditions (Cloos 1967;Riegraf et al 1984;Lehmann 1985;Tanabe et al 2000;Doguzhaeva et al 2004;Landman et al 2010). The presence of tubes in the pits somewhat contra− dicts this hypothesis because in so far as is known, the mantle musculature does not form strands of this size or form in Re− cent nautilids (see, e.g., Klug et al 2008a), and blood vessels would not have a dead end (the tubes are ending at the inside of the ammonoid shell).…”