The Yeso Group is an important Lower Permian sequence in New Mexico that records a major early marine advance from the south and the transition from arid continental landscapes to shallow marine environments. Exposed across the Rio Grande Rift, the Pecos River valley, and in the subsurface of the Raton Basin, it shows a strong north-to-south shift from desert dune and sand-sheet deposits to shoreline, sabkha, evaporite, and marine shelf settings. Though not especially fossil-rich, it has yielded marine microfossils, tetrapod footprints, plant remains, and an incomplete eupelycosaur skeleton. Its subsurface beds also became a major carbon dioxide reservoir of economic importance.