Mythbusting evolutionary issues on South American Gomphotheriidae (Mammalia: Proboscidea)

• The Gomphotheriidae analyzed sample is the largest ever included in a revision study.
• Cuvieronius hyodon and Notiomastodon platensis are the only South American gomphotheres.
• Stegomastodon is not recorded in South America.
• Amahuacatherium peruvium is not a valid taxon and its age is uncertain.
• Both Gomphotheriidae taxa are recorded in Tropical Andes and lowlands.

Despite more than two centuries of study, the South American Gomphotheriidae (SAG) taxonomy, phylogeny and biogeography are still problematic. The current knowledge about SAG is outdated and a revision of the classic concepts is necessary. Here, we analyzed a very large sample of Gomphotheriidae remains from North and South Americas. A taxonomic revision based on well-preserved diagnostic materials allowed the recognition of Notiomastodon platensis and Cuvieronius hyodon to South America, which are distributed from lowland to highland localities in this continent. Nevertheless, SAG remains of 66% of analyzed localities are not significantly diagnostic at specific level. Amahuacatherium peruvium diagnostic features are considered invalid and within the morphological variability range expected for N. platensis. The genus Stegomastodon is recognized as absent from South America and morphologically distinct of SAG taxa. The oldest record of SAG indicates that the arrival of this family in South America probably occurred during the Plio-Pleistocene, after the closure of the Isthmus of Panama.