At many excavation sites, paleontologists find more material than they are able to dig out during one field season. Large skeletons, in particular, may require years of work, and there is always the risk that when the scientists return next year, the precious bones will be missing. Sometimes this is due to the destructive power of wind and rain, but as researchers from the Cleveland Museum of Natural History found out, fossil poachers can also cause a skeleton to disappear.
In 2005, paleontologist Michael Ryan (who also writes at Palaeoblog) discovered in Mongolia the nearly complete remains of Tarbosaurus, a close relative of North America's
When he returned in 2006, the skeleton was still there, but Ryan still wasn’t able to dig it up. A full excavation was planned for the following year, and arrangements were made to feature the skeleton as the centerpiece of a new exhibit at the Cleveland Museum of Natural History. By the time the 2007 field season arrived, the bones were gone, and a broken vodka bottle, a few cigarettes, and some marks of crude excavation in the rock made it clear that the skeleton had been poached.
As Ryan notes in a blog post on Cleveland.com, poaches are not getting rich off the fossils. The money they get from the sale of the bones is paltry to what such remains eventually earn on the black market. Education and restrictions of exporting fossils might help curtail the loss of fossils, but because they can be sold for even a paltry amount of extra income in a poor region, some skeletons will be here today and gone tomorrow.