If you can identify the fossil fairly well you can often give a reasonable estimate based on the known age range of that animal. If you know where the fossil was collected you can often give a reasonable estimate based on the age range of the rock unit. Over the past 200 years research has narrowed the age brackets for many animals and for many rock units such as those in southern California. Fossils that are less than about 50,000 years old can sometimes be dated directly by measuring the amount of carbon-14, a radioactive isotope of carbon, that remains in the fossil. This technique is referred to as Carbon-14 radiometric dating. Usually, older fossils cannot be dated directly, but radiometric techniques can sometime be applied to rocks containing fossils or to rocks above or below the fossils to bracket their age. There are many age scales devised from different sources of data such as microscopic marine plankton and the geomagnetic polarity record. These age scales are combined in correlation charts to refine the age brackets for fossil animals and rocks.
Genuine fossil eggs are exciting, but very rare because eggs are fragile in life and rarely preserved in the fossil record. Upon finding a somewhat rounded rock, many people are convinced they have discovered a fossil egg. We will gladly provide our opinion as to whether you have a genuine egg or other fossil. Please send us photos of your specimens before bringing them to the Museum. Also, make sure you include a ruler or some other object for scale in your photograph so we can determine the size of the specimen.
We cannot provide appraisal values for any fossils nor do we buy or sell fossils. Reproductions of some of our specimens, casts of the original fossils, are available through various companies.
Our department houses over 150,000 vertebrate fossil specimens, representing every class of vertebrates. Our Cenozoic marine vertebrate collections are particularly extensive. The enormous collection of Rancho la Brea specimens is housed and managed separately at the Page Museum in Hancock Park.
Almost all vertebrate fossils occur in sedimentary rocks whose particles are transported and deposited by water or wind. Vertebrate fossils can also be found in asphalt deposits (including the local La Brea tarpits), in coal, in ice or permafrost, and even encased in amber.
Vertebrate fossils are discovered by people looking at exposures of sedimentary rocks, trying to spot a portion of bone or other indication of a fossil. The sedimentary rocks can be exposed either by natural weathering or by digging or excavating. You do not need formal training to look for fossils, but most people need some experience to recognize fossil bones when only a small portion is visible.
Both the fossils and the rock material that surrounds them can range from very soft to hard as concrete. For most vertebrate fossils it takes both knowledge and skill to prepare them so that they are available for research or display. Differing tools and techniques are used to prepare the fossils according to their size, their state of preservation, and the type of rock or matrix encasing them. Most frequently mechanical tools are used to pick, dig, pluck, chisel, or grind away the rock. Some rocks can be dissolved in acid, freeing fossils embedded within them.