Paleontological resources (i.e., fossils) represent a direct link with past organisms and ecosystems and as such are the primary source of evidence about the biological history of our planet.
Fossils include the remains (such as bones, teeth, shells, and wood) or traces (such as footprints, trackways, burrows, and impressions) of organisms that lived during past geological periods. For practical purposes, the temporal division between fossils and subfossils is placed at the Pleistocene/Holocene boundary; approximately 10,000 years before the present.
Fossils are typically buried in layered sedimentary rocks and can be collected and studied when those rocks are exposed at the Earth's surface. Natural exposures occur in eroding sea cliffs, valley slopes and desert badlands. Artificial exposures occur in graded road cuts, roadways, building pads, utility line trenches, and basement excavations. The conditions responsible for creating artificial exposures of sedimentary rock layers are also responsible for destruction of paleontological resources.
Because paleontological resources are an important part of our natural heritage, their destruction is considered by state and federal directives to represent a negative environmental impact.
Fortunately, such negative impacts can be mitigated. Typical mitigation programs include on-site monitoring of active excavations, discovery and recovery of exposed fossils, transportation of recovered specimens to a professional preparation/conservation laboratory, laboratory-based preparation and curation of recovered fossils in regional repositories/museums where they are available for present and future generations of citizens, students, and professional scientists.
The San Diego Natural History Museum assumes the substantial responsibility to maintain fossils collected by PaleoServices staff in perpetuity for the enjoyment and education of future generations. In addition, many salvaged fossils are being studied by researchers both here in California and across the country. Numerous scientific papers have been published on these salvaged specimens.