What happens to giant marine animals, like whales, when they die and sink? Well once the soft parts have been scavenged, you might imagine the bones would remain and the sea floor would be littered with skeletons. However, these bones provide a potential resource and life always evolves to exploit an opportunity. Introducing the Zombie worm, or Osedax if you want their proper name. These worms bore into bones and extract the lipids and fats. Well, new fossil discoveries by Silvia Danise and Nick Higgs show that these worms have been doing this for at least 100 million years. By examining the bones of marine reptiles from the Cretaceous they have identified the tell-tale markings of Osedax. Where did the authors find these remarkable fossils? In a museum's collection of course. Even if it is in a museum, a fossil can still have a myriad of secrets to reveal.
We report fossil traces of Osedax, a genus of siboglinid annelids that consume the skeletons of sunken vertebrates on the ocean floor, from early-Late Cretaceous (approx. 100 Myr) plesiosaur and sea turtle bones. Although plesiosaurs went extinct at the end-Cretaceous mass extinction (66 Myr), chelonioids survived the event and diversified, and thus provided sustenance for Osedax in the 20 Myr gap preceding the radiation of cetaceans, their main modern food source. This finding shows that marine reptile carcasses, before whales, played a key role in the evolution and dispersal of Osedax and confirms that its generalist ability of colonizing different vertebrate substrates, like fishes and marine birds, besides whale bones, is an ancestral trait.