Research ArticleANTHROPOLOGY

Footprints preserve terminal Pleistocene hunt? Human-sloth interactions in North America

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Science Advances  25 Apr 2018:
Vol. 4, no. 4, eaar7621
DOI: 10.1126/sciadv.aar7621
  • Fig. 1 Map showing WHSA, Alkali Flat, and the study site.

    Digital elevation model is from the Shuttle Radar Topography Mission 1–arc sec data with the surficial geology taken from U.S. Geographical Survey maps.

  • Fig. 2 Trackways and prints at WHSA.

    (A and B) Unexcavated sloth track. The track outlines are only visible during specific moisture conditions. (C) Flailing circle made by a sloth reaching forward with its forelimbs and leaving knuckle and claw impressions. (D) Human unshod right foot, unexcavated, and 30 mm below current surface. (E) Superimposed human and sloth track. (F to H) Unshod human feet. (I) Sloth pes track. (J and K) Human tracks superimposed in sloth tracks, indicating contemporaneity. (L and M) Manus claw impression of a sloth.

  • Fig. 3 WHSA chronology.

    (A) Summed probability density curves for extinction dates for ground sloth (8) and dates of human occupations in Southwestern United States (9, 10). Track creation probably occurred in the overlap. (B) Sequence of events on Alkali Flat.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/4/eaar7621/DC1

    fig. S1. Bluff section on the western edge of Alkali Flat adjacent to the study site.

    fig. S2. Cross sections through tracks and geotrenches.

    fig. S3. Map of part of the study site.

    fig. S4. Map of excavated tracks in part of the study site.

    fig. S5. Orthorectified mosaic of part of the study site.

    fig. S6. 3D point cloud models of excavated human tracks.

    fig. S7. 3D point cloud models of excavated tracks.

    fig. S8. 3D point cloud models of excavated tracks.

    fig. S9. 3D point cloud models of excavated tracks.

    fig. S10. Size and age estimations for excavated and unexcavated elongated tracks at and in the vicinity of the study site.

    fig. S11. (A) Orthorectified mosaic of part of the study site showing two “flailing circles” as well as sloth and human composite tracks. (B) Interpretation of trackway trajectories are based on ghost and excavated tracks.

    fig. S12. Tortuosity of sloth tracks in presence/absence of human tracks.

    table S1. Radiocarbon and OSL dates from WHSA.

    table S2. Measurements and interpretations of excavated tracks at WHSA.

  • Supplementary Materials

    This PDF file includes:

    • fig. S1. Bluff section on the western edge of Alkali Flat adjacent to the study site.
    • fig. S2. Cross sections through tracks and geotenches.
    • fig. S3. Map of part of the study site.
    • fig. S4. Map of excavated tracks in part of the study site.
    • fig. S5. Orthorectified mosaic of part of the study site.
    • fig. S6. 3D point cloud models of excavated human tracks.
    • fig. S7. 3D point cloud models of excavated tracks.
    • fig. S8. 3D point cloud models of excavated tracks.
    • fig. S9. 3D point cloud models of excavated tracks.
    • fig. S10. Size and age estimations for excavated and unexcavated elongated tracks at and in the vicinity of the study site.
    • fig. S11. (A) Orthorectified mosaic of part of the study site showing two “flailing circles” as well as sloth and human composite tracks. (B) Interpretation of trackway trajectories are based on ghost and excavated tracks.
    • fig. S12. Tortuosity of sloth tracks in presence/absence of human tracks.
    • table S1. Radiocarbon and OSL dates from WHSA.
    • table S2. Measurements and interpretations of excavated tracks at WHSA.

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