Iron technology developed independently in several parts of the world, including India and Africa.
Travois tracks
Parallel tracks have been found in fossilised mud at White Sands National Park, New Mexico, USA, and interpreted as the marks left by a travois: a timber frame used by Native Americans for transporting goods. Particularly associated with Indigenous peoples of the Great Plains region of North America, a travois is made by joining two long poles and a third shorter one to create an A-shaped frame. The shorter pole forms a platform to support the load, and the open end of the frame is typically attached to a harness and pulled by a horse.
In this case, the travois was pulled by humans, whose footprints have also survived in the fossilised mud. These have been dated to between 23,000 and 21,000 years ago using several different techniques, namely radiocarbon dating of seeds from the aquatic plant Ruppia cirrhosa and of pollen collected from the same stratigraphic horizons as the Ruppia seeds, along with optically stimulated luminescence ages of sediments from within the human footprint- bearing sequence (https://doi.org/10.1126/science.adh5007).
