Eomaia

Eomaia scansoria is an extinct genus of early mammal from the Early Cretaceous period, known from a well-preserved fossil found in the Yixian Formation of Liaoning Province, China. The genus contains a single species, Eomaia scansoria. The name Eomaia means “dawn mother,” highlighting its place among early placental-type mammals, while scansoria refers to its scansorial or climbing lifestyle.

Discovery and dating

The holotype of Eomaia scansoria was described in the mid-2000s, based on a nearly complete skeleton preserved in sediment. The specimen dates to roughly 125 million years ago, placing it among early mammals that lived alongside flowering plants and various dinosaurs in a Cretaceous ecosystem. The discovery contributed to understanding of the timing and nature of early mammalian evolution in East Asia.

Taxonomy and anatomy

Eomaia is regarded as an early mammal that falls near the base of the therian lineage, a group that later split into marsupials and placentals. Its anatomy shows a mosaic of primitive and more derived traits characteristic of early therians, including features in the skeleton and dentition that inform discussions of how and when key mammalian characteristics evolved. The fossil preserves a fairly complete body plan, with limbs and joints that suggest a mode of life involving climbing or grasping.

Significance

As one of the earlier well-preserved mammal fossils from the Cretaceous of China, Eomaia scansoria provides evidence for the early diversification of therian mammals and helps illuminate the sequence of anatomical changes in early mammalian evolution. Its fossil record supports the view that many therian features had begun to emerge by the Early Cretaceous, contributing to broader debates about mammalian ancestry and diversification.