Pairwise p-values (corrected for type I error) from t-tests of differences in surface (3D) asymmetry between style groups.

<p>Pairwise p-values (corrected for type I error) from t-tests of differences in surface (3D) asymmetry between style groups.</p

Pairwise p-values (corrected for type I error) from t-tests of differences in flake scar (2D contour) asymmetry between style groups.

<p>Pairwise p-values (corrected for type I error) from t-tests of differences in flake scar (2D contour) asymmetry between style groups.</p

P-values and robust gamma rank correlation coefficients between physical dimensions of the projectile points in the sample and log asymmetry values for respectively 2D contours of flake scar patterns (left) and 3D biface surfaces (right).

<p>P-values and robust gamma rank correlation coefficients between physical dimensions of the projectile points in the sample and log asymmetry values for respectively 2D contours of flake scar patterns (left) and 3D biface surfaces (right).</p

Distribution of log asymmetry values for 2D contours of flake scar patterns (top) and 3D biface surfaces (bottom) by style group.

<p>Distribution of log asymmetry values for 2D contours of flake scar patterns (top) and 3D biface surfaces (bottom) by style group.</p

Flake scar contours from the front and back sides were obtained as isoheight contours created by intersecting the 3D surface model with two x−y planes, each offset a distance of ¼ total specimen thickness in the positive or negative z-direction.

<p>See Sholts et al. (2012) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0179933#pone.0179933.ref007" target="_blank">7</a>] for a full description of this process.</p

Geographic distribution of the eastern projectile points used in this study, with major sites listed.

<p>Map created by author JAMG using the ArcGIS 10.3.1 software.</p

Results of F-tests for variance differences between log-transformed measures of surface (3D) asymmetry by style group.

<p>Results of F-tests for variance differences between log-transformed measures of surface (3D) asymmetry by style group.</p

Time periods and morphological definitions for the styles of projectile points analyzed in this study, adapted from [5].

<p>Chronology estimated from discussions in [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0179933#pone.0179933.ref029" target="_blank">29</a>] and [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0179933#pone.0179933.ref018" target="_blank">18</a>]. Attribute list summarized from [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0179933#pone.0179933.ref029" target="_blank">29</a>] and slightly revised for this study. Calibrated ages are presented as mean ages calculated from the CalPal online tool [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0179933#pone.0179933.ref030" target="_blank">30</a>].</p

Results of F-tests for variance differences between log-transformed measures of flake scar (2D contour) asymmetry by style group.

<p>Results of F-tests for variance differences between log-transformed measures of flake scar (2D contour) asymmetry by style group.</p

Three-dimensional models and their associated flake scar contours (superimposed flake scars from front and back faces) for projectile points of each style group.

<p>From left to right: Clovis US, Clovis East, Bull Brook, Debert-Vail, Michaud-Neponset Barnes, and Crowfield. Specimens displaying both high (top row) and low (bottom row) flake scar asymmetry are shown.</p