Gobi’s Nail-Sized Fossil Redraws Early Mammal History
A 1-centimeter jaw fragment from Mongolia’s Gobi Desert has been named Ravjaa ishiii, a new genus and species of zhelestid eutherian mammal dating to about 90 million years ago. Despite its tiny size, the fossil—found in the Bayanshiree Formation and analyzed with 3D CT imaging—exhibits distinctive tall molars and jaw features that justify placing it as a new early relative of placental mammals, potentially the oldest zhelestid known. Reported in Acta Palaeontologica Polonica, the discovery suggests these mammals were already exploiting flowering-plant resources during the Late Cretaceous and highlights the Bayanshiree Formation’s rarity for mammal fossils.
