An ammonite–fish association from the Kimmeridgian (Upper Jurassic) of La Rochelle, western France

Abstract

International audienceA partially disarticulated actinopterygian fish preserved in a large three-dimensional ammonite body chamber is described from the Kimmeridgian of western France. Taphonomic observations on the degree of preservation of the fish and the development of epibiont organisms on the inner wall of the shell indicate a rather long time interval before sediment totally filled the body chamber. The fish, referred to an indeterminate Macrosemiidae, probably used this empty ammonite (Rasenioides, Aulacostephanidae) shell as a refuge, or possibly for spawning and/or brooding. It can be assumed that ammonite shells may have constituted common shelters for demersal fishes living in an open-marine shelf environment, near to a muddy bottom devoid of rocks

Exceptionally Preserved Late Jurassic Gastropod Egg Capsules

“…Similar egg capsule deposition was previously noted in Early Jurassic (Pliensbachian) gastropods by Kaiser and Voigt (1983). This should not be surprising as empty ammonite shells provided a suitable cryptic space, both for spawning as well as sheltering (e.g., Fraaije 2003;Vullo et al 2009;Klompmaker and Fraaije 2012;Wilson and Taylor 2012). Deposition of the egg capsules in such places also certainly promoted their survival as they were well protected from other animals and extrinsic physical factors.…”

Animal Behavior Frozen in Time: Gregarious Behavior of Early Jurassic Lobsters within an Ammonoid Body Chamber

“…The presence of fish in mollusk and cephalopod shells is often proposed to be for protective reasons for the fish themselves (e.g. [11] , [12] , [70] , [71] , [72] ), but fish also may have been actively hunting for prey hidden inside shells. There are numerous examples of predatory fish in ammonoid shells.…”

“…There are numerous examples of predatory fish in ammonoid shells. For example, the presence of a macrosemiid fish, most likely a predatory fish, in a Late Jurassic (Kimmeridgian) ammonoid shell is known [72] and four Early Jurassic ammonoids from Germany and England contained one predatory fish ( Dapedium sp. and Pholidophorus sp.)…”

Gastropod egg capsules preserved on an Early Cretaceous ammonite from Daghestan, Russia

“…Such inquilinism, or usage of the empty shells by other animals for hiding, spawning or moulting, has been described several times. For example, Jurassic and Cretaceous ammonite shells were commonly used by crustaceans (e.g., Fraaye and J€ ager 1995; Klompmaker and Fraaije 2012; Landman et al, 2014), including hermit crabs (Fraaije 2003), as well as fishes (Vullo et al, 2009). However, except hermit crabs that certainly used the shells for protection, the role of ammonite shells in the case of other animals is uncertain and the authors usually propose several alternatives.…”