Size alone dictates that invertebrate and microfossil collections face particularly difficult issues. Current Status Of Paleontological Collections Size . National and global compilations of the data that are available are incomplete. This compilation did not, however, include adequate data from several countries with large collections, including Belgium, China, Germany, and India. These are clearly only partial numbers.
Collections held by the petroleum industry are also very difficult to assess.
The total number may therefore be around 12-16 million samples. Surveys of non-U.S. industrial collections are scarcer. A world-wide number of 100 million samples in all industrial collections is therefore not inconceivable. Collections held by private individuals are even more difficult to inventory. This would amount to a total of 2.5 million specimens.