An Ichthyosaur Carcass-Fall Community From the Posidonia Shale (Toarcian) of Germany

Evaluating the Existence of Vertebrate Deadfall Communities from the Early Jurassic Posidonienschiefer Formation

“…The oryctocoenosis described in [17] represents the sole multitaxon assemblage consisting of a large number of individuals associated with an ichthyosaur carcass from the Posidonienschiefer Formation. In addition to elements attributed to the enrichment-opportunist stage, such as an ophiuroid and ammonites, a well-developed reef stage consisting of four epifaunal bivalve genera and a crinoid was described.…”

“…However, both the presence of the ammonites and the bivalves Parainoceramya dubia (formerly Pseudomytiloides dubius) and Bositra require reappraisal, as these might represent chance associations: these taxa are relatively abundant in the Posidonienschiefer Formation, and are frequently encountered without being associated with vertebrate carcasses. Dick [17] listed additional examples of marine reptile deadfall communities from the Posidonienschiefer Formation, but many of these may be spurious for similar reasons discussed for the Coelodiscus associations. One ichthyosaur specimen, SMNS 80234, represents a notable exception, being associated with two partially articulated ophiuroids potentially representing enrichment opportunists.…”

“…While the latter approach was not systematic, it is clear that such associations are relatively uncommon and thus anecdotal findings are worthy of mention. Previous authors have considered macroinvertebrates within 10 cm of the bones to be associated with the deadfall community [11,17]. This approach is extremely conservative, as in recent whale fall communities, the area enriched by the decaying carcass can extend 1-3 m around the carcass, and this is also the case for smaller actinopterygian bait parcels [1,2].…”

“…Hexanchid shark and ichthyosaur teeth preserved in association with marine reptile carcasses have been interpreted as representing the mobile scavenger stage [14,15]. Ophiuroids were reported as associated with the enrichment opportunist stage in Lower and Upper Jurassic marine reptile carcasses [16,17]; oysters and serpulid worms have been documented as important components of the reef stage on many marine reptile carcasses spanning the Jurassic; e.g., [16,18,19]. The most complete Jurassic fall succession was reported in [11] on an Upper Jurassic ichthyosaur carcass.…”

A new specimen ofPalvennia hoybergeti: implications for cranial and pectoral girdle anatomy in ophthalmosaurid ichthyosaurs

“…5 ; Delsett et al, 2016 ). The specimen was covered with crinoid, ophiuroid, and bivalve remains, possibly indicating prolonged exposure on the sea bottom in oxygenated bottom waters as an “ichthyosaur fall,” and scavenging might be a cause for the partly disarticulated status ( Dick, 2015 ; Delsett et al, 2016 ). The elements of the rostrum (splenials, dentaries, and premaxillae) and the anterior part of the nasals are preserved together with the teeth anteriorly.…”