Do fossil tracks in ancient sediments reflect animal activity?
Modern trails produced by cm-sized, globular amoebas on the sea floor off the Bahamas coast (Matz et al., 2008: Current Biology, 18, 1849) may provide clues about the origin of some Precambrian fossil traces, including the controversially old Stirling Range trails in Western Australia. Curtin geologist Birger Rasmussen and Swedish colleague Stefan Bengtson speculate that the ability of modern giant amoebas to generate trails, which are uncannily similar to those discovered in the ca. 2 billion-year-old Stirling Ranges, raises the possibility that such trails do not necessarily indicate the presence of animals (Science 2009, vol. 323, 346-7 “New and ancient trace makers”). The latter point has been hotly debated since Rasmussen and colleagues established the age of the rocks hosting the Stirling Range trace fossils using the John de Laeter Centre SHRIMP facilities (Science, 2002: vol. 296, 1112-1115; Precambrian Research, 2004: vol. 133, 329-337), but left open the question about what m
