Codex Selden
"The Codex Selden (also known as the Codex Añute) is a Mexican manuscript of Mixtec origin. The codex is an account of the genealogy of the Jaltepec dynasty from the tenth to the sixteenth century. The Codex Selden is actually a fragment of a much longer document. Although it was completed after the arrival of the conquistadors in the Mixtec region, it is considered as one of the six pre-Hispanic Mixtec codices that survived the Spanish conquest of Mexico.
The Codex belonged to the English jurist John Selden, who died in 1654 and left his collection of books and manuscripts at the University of Oxford. It is kept at the Bodleian Library in Oxford.
In the 1950s, an accidental scratch revealed that the Selden Codex might overlay an earlier document later covered over with a layer of gypsum and chalk, a palimpsest. But given the fragility of the Codex, the faint tracings seen through the scratch could not be further revealed. Traditional x-ray techniques would not be effective since the tracings were organic in composition."
In 2016, researchers reported that they had successfully unveiled the underlying pre-Columbian writing using a newer scanning technique. Early analysis of the writing suggests that the original writing includes a history of the Mixtec culture with hitherto unknown details." (Wikipedia)