Purchased specimens should always be obtained from a reputable dealer. When buying a specimen, you should ask the dealer to demonstrate, in writing, that they are in possession of full and unencumbered title to the specimen, and that the specimen was obtained by them in full compliance with all the relevant local, state, Federal, and international laws, including those of the country of origin.
There has been an increase in the use of the Internet for the sale and purchase of fossil specimens. As with any valuable item purchased over the Internet, the buyer must use particular caution. Documentation on the ownership, provenance and legality of the specimen should be required in advance.
In their Policy Statement regarding the sale of vertebrate fossils online, The Society of Vertebrate Paleontology states “The barter, sale, or purchase of scientifically significant vertebrate fossils is not condoned, unless it brings them into or keeps them within a public trust. We are deeply concerned by the on-line, auction sale of vertebrate fossils, as the nature of the process cannot assure that scientifically significant fossils are deposited into not-for-profit scientific and educational institutions.”
There is, unfortunately, a thriving market in illegally collected (and often illegally exported) fossils, and if you fail to check the provenance of the specimen properly, you are running the risk of acquiring stolen goods. If you are acquiring the specimen for a personal collection you should remember that a specimen with solid paperwork documenting its provenance is inherently more valuable scientifically.
It’s a good idea to require that the seller sign a specimen, which is a document containing a description of the object(s) involved and the precise conditions of transfer. Copies of all invoices, bills of sale, and receipts relating to the purchase should be kept on file permanently.
For more information on specimen data and documentation see Specimen data.