Soft-tissue preservation in the Middle Jurassic ammonite Cadoceras from Central Russia

Abstract

The findings of fossilized ammonite soft tissues are extremely rare, so each specimen may be important for understanding the anatomy of these cephalopods. This paper deals with soft tissue fragments and imprints preserved in the rear part of the body chamber of the Middle Jurassic ammonite Cadoceras stupachenkoi from Central Russia. At the base of the body chamber of this ammonite in front of the last septum, a mantle fragment with clearly visible longitudinal fibers and imprints of the palliovisceral ligament are preserved. In front and slightly to the side of the mantle fragment, a small area with branched structures is located; probably, these structures are fragments of gills. In general, the structure of the soft tissues in the rear part of the ammonite body looks very similar to that of modern nautilids, with one exception: mantle fibers are not directed forward as observed in Nautilus, but to the mid-ventral line, probably to the ventral muscle.

Taphonomic history and trophic interactions of an ammonoid fauna from the Upper Triassic Polzberg palaeobiota

“…The area and outline of the black mass correlates with similar lateral attachment scars of muscle for the hyponome retractor in Jurassic ammonoids from Russia 39 , see 40 . Similar structures were described as ventrolateral muscle scars in Cretaceous Aconeceras from Russia 41 .…”

Failed prey or peculiar necrolysis? Isolated ammonite soft body from the Late Jurassic of Eichstätt (Germany) with complete digestive tract and male reproductive organs

“…In all cephalopods, the gills are attached to the posterior part of the mantle cavity (Lehmann and Weitschat 1973 ; Lehmann 1981 , 1985 ; Reitner 2009 ; Sasaki et al 2010 ; Klug et al 2015 , 2019 ; Mironenko 2015a ). From ammonites, only very few good records of gill remains are available from the Mesozoic (Lehmann and Weitschat 1973 ; Lehmann 1985 ; Mironenko 2015a ). In all cases, the gills are located ventrally in the posterior mantle cavity.…”

“…Most ammonoid materials preserving remains of the soft parts come from conservation deposits worldwide. These include specimens from the Late Devonian of Morocco (Klug et al 2016a , b ), the Early Carboniferous of Bear Gulch (Landman et al 2010 ; Klug et al 2019 ; Mapes et al 2019 ), the Late Carboniferous of Paraguay (Closs 1967a , b ; Bandel 1988 ; Lehmann et al 2015 ), the Permian of the USA (Tanabe et al 2000 ); the Early Triassic of Greenland (Lehmann 1985 ), the Middle Triassic of Germany (Klug and Jerjen 2012 ), the Late Triassic of Austria (Doguzhaeva et al 2004 ), the Early Jurassic of Germany (Lehmann and Weitschat 1973 ; Wetzel 1979 ; Lehmann 1985 ; Riegraf et al 1984 ) and Great Britain (Lehmann and Weitschat 1973 ), the Middle Jurassic of Russia (Mironenko 2015a ), the Late Jurassic of Germany (Schweigert and Dietl 1999 ; Mapes et al 2019 ), as well as the Late Cretaceous of Lebanon (Wippich and Lehmann 2004 ) and of Germany (Klug et al 2012 , 2015 ).…”

First discovery of the soft‐body imprint of an Oligocene fossil squid indicates its piscivorous diet

“…Phosphatization is the main type of preservation of soft-bodied marine animals including coleoids, in all currently known Konservat-Lagerstätten localities, such as Jurassic Posidonia Shales, Oxford Clay Formation, Solnhofen Plattenkalks, etc., their bodies are phosphatized (Donovan & Fuchs 2016). Soft tissues of ammonites, such as their mantle and muscle fragments (Mironenko 2015;Klug et al 2021b) and siphuncle blood vessels (Tanabe et al 2000;Mironenko 2017), are also replaced with phosphatic minerals, although the preservation of ammonite bodies is usually incomplete, with very rare exceptions (Klug et al 2021b).…”