Due to a beginning tuberculosis, he traveled to Brazil in 1825 and spent the following three and a half years collecting specimens of plants, birds and insects in the area around Rio de Janeiro, and writing about ants, snails and birds of the region [REF].
In his Discours sur les révolutions de la surface du globe (1825), Cuvier theorized that the extinction of species was caused by natural catastrophes in certain regions of the world.