The Burgess Shale
520 million years ago a community of strange animals living on and around the sea bed were buried under a mud slide, in what is now British Columbia. Very unusually, the geological processes which turned this mud into rock did not destroy the soft parts of these animals, but preserved them in fine detail. For the first time, the soft parts of animals such as trilobites could be studied, but far more dramatically, a wide range of seemingly bizarre and unique soft-bodied animals were preserved. The Burgess Shale, as this rock is now called, gives us a special insight into life in the Lower Cambrian.
Many of these creatures are so unlike animals alive today, or known from fossils, that researchers working on them had difficulty working out exactly how they might have looked. The Burgess Shale has become famous for the remarkably bizarre range of creatures found in it, and for the scientific debate about what they mean. Was life at the time of the Burgess Shale very different from later times ... or is the Burgess Shale just giving us a clue to what might be missing from all faunas?
The images show an artist's impression of Pikaia (top), one of the first creatures with a spinal cord, and Hallucigenia, a paradoxical creature whose form remained a mystery to paleontologists for many years.