Extraordinary Preservations: More Than Rare Stills In the Movie of Life

Fossil deposits that retain evidence of soft-bodied organisms provide a much more complete representation of ancient communities than does the normal fossil record. Research on these deposits has moved from the fringes of paleontology to center stage. In addition to revealing novel morphologies and documenting stratigraphic ranges, these extraordinary preservations yield critical data on major events in the history of life. Their importance has increased with the current focus on the origin and early evolution of metazoans and patterns of biodiversity through time.

Discoveries of extraordinary fossils have had a substantial impact over the last 100 years. Most important have been deposits that illuminate significant evolutionary events. The Burgess Shale was discovered just a year after the foundation of the Paleontological Society and, together with other Cambrian deposits (e.g. Chengjiang, Sirius Passet), has revolutionized our understanding of the Cambrian explosion. The remarkable fossils of the Ediacaran Period include large-bodied organisms, some of them (vendobionts) apparently unrelated to metazoans, that predate the events of the Cambrian. Extraordinary preservations have also yielded evidence of early stages in the colonization of land (e.g. Devonian Rhynie Chert), and the origins of vertebrate flight (e.g. Jurassic Solnhofen Limestone). In other cases evidence of soft parts has resolved long standing debates about the affinities of enigmatic groups. The first description of a complete conodont animal, for example, was published 25 years ago, and conodonts have turned out to be central to debates about the origin of the vertebrate skeleton. Specimens from the Cretaceous of Liaoning, China have confirmed that some dinosaurs were feathered. Extraordinary preservations from newly exploited taphonomic settings, such as phosphorites (Doushantuo embryos) and concretions in volcanic ash (Silurian of Herefordshire), using modern tomographic techniques, continue to yield essential data on the history of life.