Walking in mud: Remarkable Pleistocene human trackways from White Sands National Park (New Mexico)

Human tracks at White Sands National Park record more than one and a half kilometres of an out‐ and‐back journey and form the longest Late Pleistocene‐age double human trackway in the world. An adolescent or small adult female made two trips separated by at least several hours, carrying a young child in at least one direction. Despite giant ground sloth and Columbian Mammoth transecting them between the outbound and return journeys, the human tracks show no changes indicative of predator/prey awareness. In contrast, the giant ground sloth tracks show behaviour consistent with human predator awareness, while mammoth tracks show no such apparent concern. The human footprints are morphologically variable and exhibit left‐right asymmetry, which might be due to child carrying. We explore this morphological variability using methods based on the analysis of objective track outlines, which add to the analytical toolkit available for use at other human footprint sites. The sheer number of tracks and their remarkable morphological variability have implications for the reliability of inferences made using much smaller samples as are more common at typical footprint sites. One conclusion is that the number of footprints required to make reliable biometric inferences is larger than often assumed

The morphological affinity of the Early Pleistocene footprints from Happisburgh, England, with other footprints of Pliocene, Pleistocene, and Holocene age.

Fossil hominin footprints provide a direct source of evidence of locomotor behavior and allow inference of other biological data such as anthropometrics. Many recent comparative analyses of hominin footprints have used 3D analytical methods to assess their morphological affinities, comparing tracks from different locations and/or time periods. However, environmental conditions can sometimes preclude 3D digital capture, as was the case at Happisburgh (England) in 2013. Consequently, we use here a 2D geometric morphometric approach to investigate the evolutionary context of the Happisburgh tracks. The comparative sample of hominin tracks comes from eight localities that span a broad temporal range from the Pliocene to Late Holocene. The results show disparity in the shapes of tracks ascribed to hominins from the Pliocene (presumably Australopithecus afarensis), Pleistocene (presumably Homo erectus and Homo antecessor), and Holocene (Homo sapiens). Three distinct morphological differences are apparent between time samples: changes in adduction of the hallux, changes in the shape and position of the medial longitudinal arch impression, and apparent changes in foot proportions. Linear dimensions classified the potential H. antecessor tracks from Happisburgh as being most similar to the presumed H. erectus prints from Ileret. We demonstrate using 2D geometric morphometric methods and linear dimensions that the Happisburgh tracks are morphologically similar to other presumed Homo tracks and differ from the Laetoli footprints. The probable functional implications of these results fit well with previous comparative analyses of hominin tracks at other sites