White Sands fossil footprints
The White Sands fossil footprints are a set of fossilized human footprints discovered in 2009 in the White Sands National Park in New Mexico. In 2021 they were radiocarbon dated, based on seeds found in the sediment layers, to between 21,000 and 23,000 years ago.[1] That date range is currently the subject of scientific debate, but if it is correct, the footprints would be one of, if not the oldest record of humans in the Americas. The earlier theory held that human settlement of the Americas began at the end of the last Ice Age, about 13,000 years ago.[2][3][4]
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The 61 footprints are located at the shore of an ice age era lake in the Tularosa Basin.[5] The prints were found in seven soil layers and provide evidence of human occupation spanning approximately 2000 years. The prints have "good anatomical definition (i.e. visible heal impressions, medial longitudinal arches and toe pads)".[1] They are flatter-footed than those that are left by people who habitually wear shoes and, in this respect, are similar to fossil footprints found in Namibia. They appear to have been made, for the most part, by teenagers and children, with few large adult footprints being found in any of the excavated surfaces. The tracks are associated with those of extinct megafauna, such as Columbian mammoths and ground sloths.[1]
In 2022, skeptics noted that age estimates relied on carbon dating Ruppia cirrhosa seeds, whose parent plants can intake carbon from groundwater, thereby potentially resulting in dates thousands of years too old,[4][6] with a study accounting for this effect suggesting that the maximum age of the footprints is likely only 15,500–13,500 is calibrated years Before Present, comparable with many other archaeological sites across the Americas.[7] A 2023 study that included radiocarbon dating of pollen and optically stimulated luminescence dating (OSL dating) of quartz grains within the footprint layers corroborated the original dates obtained from the seeds,[6][8] though these dates have also been considered uncertain by other authors, who suggest that they represent maximum ages, rather than true age estimates, due to the OSL dating being only taken from a layer below the footprints, and the potential for old pollen to be eroded and redeposited into younger layers.[9]
References
[edit]- ^ a b c Bennett, Matthew R.; Bustos, David; Pigati, Jeffrey S.; Springer, Kathleen B.; Urban, Thomas M.; Holliday, Vance T.; Reynolds, Sally C.; Budka, Marcin; Honke, Jeffrey S.; Hudson, Adam M.; Fenerty, Brendan; Connelly, Clare; Martinez, Patrick J.; Santucci, Vincent L.; Odess, Daniel (2021-09-24). "Evidence of humans in North America during the Last Glacial Maximum". Science. 373 (6562): 1528–1531. Bibcode:2021Sci...373.1528B. doi:10.1126/science.abg7586. ISSN 0036-8075. PMID 34554787. S2CID 237616125.
- ^ Zimmer, Carl (September 23, 2021). "Ancient Footprints Push Back Date of Human Arrival in the Americas". The New York Times. ISSN 0362-4331. Retrieved April 8, 2022.
- ^ Gershon, Livia (September 24, 2021). "Prehistoric Footprints Push Back Timeline of Humans' Arrival in North America". Smithsonian Magazine. Retrieved April 8, 2022.
- ^ a b Madsen, David B.; Davis, Loren G.; Rhode, David; Oviatt, Charles G. (2022-10-14). "Comment on "Evidence of humans in North America during the Last Glacial Maximum"". Science. 375 (6577). American Association for the Advancement of Science: eabm4678. doi:10.1126/science.abm4678. PMID 35025634. Retrieved 2023-08-23.
- ^ "The discovery of ancient human footprints in White Sands National Park and their link to abrupt climate change". United States Geological Survey. Earth Science Matters Newsletter. Retrieved 23 April 2022.
- ^ a b Johnson, Carolyn (October 5, 2023). "Ancient footprints upend timeline of humans' arrival in North America". The Washington Post. Retrieved October 6, 2023.
- ^ Rachal, David M.; Dello-Russo, Robert; Cuba, Matthew (January 2024). "The Pleistocene footprints are younger than we thought: correcting the radiocarbon dates of Ruppia seeds, Tularosa Basin, New Mexico". Quaternary Research. 117: 67–78. Bibcode:2024QuRes.117...67R. doi:10.1017/qua.2023.74. ISSN 0033-5894. S2CID 266946359.
- ^ Pigati, Jeffrey S.; Springer, Kathleen B.; Honke, Jeffrey S.; Wahl, David; Champagne, Marie R.; Zimmerman, Susan R. H.; Gray, Harrison J.; Santucci, Vincent L.; Odess, Daniel; Bustos, David; Bennett, Matthew R. (2023). "Independent age estimates resolve the controversy of ancient human footprints at White Sands". Science. 382 (6666): 73–75. Bibcode:2023Sci...382...73P. doi:10.1126/science.adh5007. PMID 37797035. S2CID 263672291.
- ^ Steffen, Martina L. (2024-02-21). "New age constraints for human entry into the Americas on the north Pacific coast". Scientific Reports. 14 (1): 4291. doi:10.1038/s41598-024-54592-x. ISSN 2045-2322. PMC 10881565. PMID 38383701.
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