BOOM Goes the Ichthyosaur? | Wired Science | Wired.com
The ichthyosaurs of Holzmaden, Germany are among the most exquisite fossils ever discovered. Many of their skeletons have been left in stunning, articulated detail, and the very outlines of their ichthyosaurian bodies were preserved by the bacteria which decomposed their carcasses after the marine reptiles had settled to the bottom of the Jurassic sea. It was specimens like these, which clearly showed the outlines of dorsal fins and tail flukes supported by downward-kinked tails, that caused paleontologists to see ichthyosaurs are swift, reptilian tuna mimics and not the slow, paddle-bearing lizards envisioned by 19th century naturalists.
But what happened between the time the Holzmaden ichthyosaurs died and when they sank to the ocean bottom? Did the predators fall through the water column as soon as they died, or did they float until the gases from decomposition exploded their bodies and scattered their bones? That is what paleontologists Achim Reisdorf and co-authors consider in a new paper given one of the more evocative titles in recent memory, “Float, explode or sink: postmortem fate of lung-breathing marine vertebrates.”
The problem of how ichthyosaurs went to pieces is difficult to approach. For one thing, the marine reptiles died out tens of millions of years ago – ichthyosaurs swam the world’s oceans from 245 to 90 million years ago, disappearing before the end-Cretaceous extinction rocked the world. Direct observation is right out. And ichthyosaurs don’t have any close living relatives among the reptiles, nor has any reptilian lineage converged on the ichthyosaur body plan.