Export bans: China, Mongolia, Brazil, Argentina, Morocco

China declares fossils, especially vertebrates, part of the national heritage. The Regulations on the Protection of Paleontological Fossils (2011) require State Council approval for any export of key protected fossils; in practice the feathered dinosaurs, Jehol birds and Keichousaurus that appear on the market left without it. Buying them exposes the buyer to seizure and, for a dealer, to trafficking charges.

Mongolia's constitution and its heritage laws make all fossils state property; export has been prohibited since the 1920s. The 2012–2013 Tarbosaurus bataar case, in which a skeleton sold at auction in New York was seized and returned, established that US courts will act on Mongolian claims. Assume any Mongolian dinosaur material offered for sale is contraband.

Brazil's Decree-Law 4,146 (1942) makes fossil deposits national property; extraction needs authorisation from the national mining agency and export is not permitted. The Crato and Santana formation fish, insects and pterosaurs that fill European and American collections were exported illegally, and Brazilian authorities have been requesting repatriation with growing success.

Argentina's Law 25,743 (2003) declares paleontological heritage the property of the state or the provinces and prohibits export without authorisation, which is not given for commercial purposes. Patagonian dinosaur material and Argentine ammonites offered without documents fall under it.

Morocco is different in kind: its trilobites, ammonites and phosphate shark and mosasaur teeth are exported in quantity through a regulated trade with customs paperwork, and this is lawful. Moroccan heritage law (22-80, as amended) nonetheless covers fossils, and scrutiny of significant vertebrate material — Spinosaurus, Kem Kem dinosaurs — has increased. Keep the customs and invoice trail for every Moroccan lot.

For all five: a specimen that left the country before the relevant law took effect can be legal to own and sell, and the documentary evidence of that date — old collection labels, auction catalogues, customs stamps — is what makes it so. Stratum's import date and import documentation fields exist for this.