310 LAGERSTAă TTEN Table A small selection of conservation Lagerstatten with age, location, and brief comments on the environmental conditions and preservation of soft parts (sp.) Lagerstaătten Age Location Brief comments Doushantuo Formation Chengjiang Latest Proterozoic Early Cambrian South China Burgess Shale Orsten Middle Cambrian Late Cambrian Soom Shale Late Ordovician Herefordshire Silurian Yunnan Province, China British Columbia, Canada Southern Sweden, Germany and Poland Cape Province, South Africa Herefordshire, UK One deposit in carbonaceous shales, another in phosphorites phosphatisation of sp Burgess Shale type fauna, microturbidites various mineral replacement of sp and possible organic remains Burgess Shale type fauna, obrution and anoxia, kerogenised organic films and clay mineral replacement of sp Anthraconite limestone nodules in bituminous shale, apatite (phosphatic) coating and replacement of sp Hunsruck Slate Rhynie Chert Early Devonian Western Germany Early Devonian Eastern Scotland Pennsylvanian Carboniferous Middle Triassic Illinois, USA Mazon Creek Monte San Giorgio Posidonia Shale Solnhofen Limestone Santana Formation Grube Messel Baltic Amber Lower Jurassic Upper Jurassic Lower Cretaceous Mid Eocene Late Eocene Early Oligocene Southern Switzerland Holzmaden region, Germany Southern Germany NE Brazil West Germany Baltic, NW Europe Euxinic and anoxic bottom and porewaters, clay mineral replacement of sp Calcite nodules in volcanic ash deposit after decay three dimensional animal void infilled by calcite Obrution by microturbidites pyrite replacement of sp Plants and arthropods engulfed in Si rich hotspring water silicification of sp Rapid burial in oxygen depleted sediment and siderite nodules sp represented as highly compressed, light on dark impressions Bottom waters anoxic, but surface waters normal marine rare phosphatised sp., mostly articulated skeletons Anoxic bottom waters, soupy sediment and occasional sediment blanketing, sp of belemnites, cephalopods Hypersaline, oxygen depleted bottom waters, soupy sediment obrution and microbial mats Soft parts mostly impressions rare phosphatisation of sp and organic residues Hypersaline waters, soupy sediment, and mass mortalities many carbonate concretions and sp phosphatised Quiet, anoxic lacustrine waters silhouettes of sp made of autolithified, sideritic bacterial films Amber is fossilized resin from trees, which traps arthropods; resin stops bacterial and fungal decay and acts as desiccant and antibiotic sediment layer(s) rather than being constrained to special, localized settings, as is the case for conservation traps Scavenging by macro-organisms is a ubiquitous event in most environments and leads to disarticulation, and sometimes wide dispersal of the animal hard parts, and the removal of soft parts Terrestrial and aquatic environments abound with macroscavengers and they may devour soft tissues in surprisingly little time For example, a fish carcass introduced to a cold (4 C), dysaerobic seabed off the coast of California was stripped of soft parts and disarticulated in 2–3 days by brittle stars Clearly, one of the most important prerequisites for exceptional preservation is the precludement of macroscavengers from carcasses and plants This may be accomplished in a variety of ways, some of which are illustrated below, using examples from fossil conservation Lagerstaă tten Obrution Catastrophic, rapid burial, by turbidites or tempestites, may help to preserve nonmineralised tissues because it protects the animal (which may be buried dead or alive) from macroscavengers and bioturbators, (see Trace Fossils) and it tends to induce anoxia (see below) However, whilst there are fewer bacteria with depth, and anaerobic bacteria are less efficient at breaking down organic carbon, a rapidly buried carcass still requires other processes to occur to inhibit or circumvent the decay of organic remains Sediment smothering often produces an ecological bias because it will affect bottom-living organisms more than nektonic ones In the Phyllopod Bed of the Middle Cambrian Burgess Shale (British Columbia, Canada) there is evidence to suggest that much of the biota was catastrophically buried, such as graded beds and variable orientations of specimens relative to bedding (Figure 2) Furthermore, Phyllopod Bed sediments are parallel laminated (i.e., undisturbed) suggesting that, owing to anoxia, conditions in the sediment porewaters were inimical to bioturbators and scavengers Soupy substrates Burial owing to high rates of sedimentation is not the only way of rapidly covering a