An analysis of the mouthparts of 505-million-year-old fossils suggests that the animals could be among the world's earliest molluscs.
Martin Smith of the University of Toronto, Canada, analysed more than 300 fossils belonging to two early invertebrate groups, Odontogriphus and Wiwaxia, that have been variously classified as molluscs, annelids or a common ancestor. The fossils are from British Columbia's Burgess Shale, which provides a record of an explosion in new body forms that occurred around the Cambrian era (542 million to 488.3 million years ago).
The mouthparts of many of the fossils — rows of jagged teeth that rest on a grooved tongue — resemble those of modern-day molluscs. The teeth might have worked like a file, allowing the animals to grind soft tissues, the author suggests.
Proc. R. Soc. B http://dx.doi.org/10.1098/rspb.2012.1577 (2012)