Molecular phylogenetics unveils the ancient evolutionary origins of the enigmatic fairy armadillos

► First molecular data ever obtained for the rare Chacoan fairy armadillo (Calyptophractus retusus) from a museum specimen. ► Fairy armadillos are monophyletic and represent a major armadillo subfamily (Chlamyphorinae) grouping with Tolypeutinae. ► Ancient divergence date (∼17 Mya) supports their classification in two distinct genera Calyptophractus and Chlamyphorus. ► Vicariant origin of fairy armadillos likely triggered by Middle Miocene marine incursions in the Paraná river basin. ► Phylogenetic distinctiveness and rarity in the wild argue in favor of high conservation priority for fairy armadillos.