Cuatro Cienegas Footprints

Two sets of well-preserved human footprints discovered in tufa sediments within the Cuatrociénegas Basin represent the oldest known footprints in Mexico [1]. U-series dating yielded ages of 10,550 ± 30 years BP for the older, isolated prints and 7,240 ± 130 years BP for a trackway containing eleven in situ footprints [1]. The older footprints' precise location remains unknown [1], while the younger trackway provides evidence of human movement across the basin during the Early Holocene. Oxygen and carbon isotope analysis indicates the tufa with in situ footprints formed during a transition to warmer and drier conditions.