Dead ichthyosaurs did not explode!

[Ben Creisler <bcreisler@gmail.com>]

From: Ben Creisler
bcreisler@gmail.com

A new study and a link to a new article:

Achim G. Reisdorf, Roman Bux, Daniel Wyler, Mark Benecke, Christian
Klug, Michael W. Maisch, Peter Fornaro and Andreas Wetzel (2012)
Float, explode or sink: postmortem fate of lung-breathing marine vertebrates.
Palaeobiodiversity and Palaeoenvironments (advance online publication)
DOI: 10.1007/s12549-011-0067-z
http://www.springerlink.com/content/952610xv7h737814/

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.

News story and blog links:
http://www.guardian.co.uk/education/2012/feb/13/dinosaur-ichthyosaur-vertical-fossil-exploding?newsfeed=true

http://www.wired.com/wiredscience/2012/02/boom-goes-the-ichthyosaur/