Ichthyosaur embryos outside the mother body: Not due to carcass explosion but to carcass implosion

Abstract

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. © 2013 The Author(s).