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In his recent discussion on the taphonomy of ichthyosaurs, van Loon (2013) supported—at least partially—the view of Reisdorf et al. (2012) and emphasized that explosion of vertebrate carcasses on the sea floor should not be considered as a taphonomically reasonable scenario. Carcass explosion is thus not a process that can be used to explain both the disarticulation of certain ichthyosaur skeletons and the displacement of their bones in the geological record. Van Loon (2013), however, did suggest that, as an alternative hypothesis, implosion could have led to the displacement of bones on the sea floor. Van Loon (2013) focussed his explanation of the implosion hypothesis on the example of a maternal ichthyosaur having embryonic ichthyosaurs around and within its body cavity (Staatliches Museum fur Naturkunde Stuttgart, specimen number SMNS 50 007). Reisdorf et al. (2012) outlined that

Some well-preserved ichthyosaurs found in the Early Jurassic Posidonienschiefer Formation at Holzmaden (Germany) have puzzled palaeontologists for a long time: their skeletons are exceptionally well preserved and their bones are almost all in situ, but the bones of their embryos are scattered, partly beyond the body limits of the mother. This has been explained initially by bottom currents and later by a displacement of already disarticulated embryos during the expulsion of putrefaction gases through the disrupted body wall of the mother. It was postulated recently that this latter hypothesis is not tenable. It is argued here that both hypotheses are not tenable in their original form, but that carcass implosion may explain the various enigmatic features.

What happens after the death of a marine tetrapod in seawater? Palaeontologists and neontologists have claimed that large lung-breathing marine tetrapods such as ichthyosaurs had a lower density than seawater, implying that their carcasses floated at the surface after death and sank subsequently after leakage of putrefaction gases (or ‘‘carcass explosions’’). Such explosions would thus account for the skeletal disarticulation observed frequently in the fossil record. We examined the taphonomy and sedimentary environment of numerous ichthyosaur skeletons and compared them to living marine tetrapods, principally cetaceans, and measured abdominal pressures in human carcasses. Our data and a review of the literature demonstrate that carcasses sink and do not explode (and spread skeletal elements). We argue that the normally slightly negatively buoyant carcasses of ichthyosaurs would have sunk to the sea floor and risen to the surface only when they remained in shallow water above a certain temperature and at a low scavenging rate. Once surfaced, prolonged floating may have occurred and a carcass have decomposed gradually. Our conclusions are of significance to the understanding of the inclusion of carcasses of lung-breathing vertebrates in marine nutrient recycling. The postmortem fate has essential implications for the interpretation of vertebrate fossil preservation (the existence of complete, disarticulated fossil skeletons is not explained by previous hypotheses), palaeobathymetry, the physiology of modern marine lung-breathing tetrapods and their conservation, and the recovery of human bodies from seawater.