Robert Z Selden Jr, lithics, stone tools, biface, Gahagan, Gahagan Mound, Caddo, Louisiana, archaeology, archeology, illustration, flake scar, geometric morphometrics, shape, form, allometry, asymmetry

TAS blog post on Gahagan biface shape and new preprint on SocArXiv

A blog post associated with a project that John E. Dockall and I have been working on was recently added to the Texas Archeological Society’s website, and can be viewed here.

Illustrations of Gahagan bifaces from the Gahagan Mound site in Northwest Louisiana. We are now looking at flake scar and beveling morphology associated with Gahagan biface retouch and refurbishment by Caddo knappers.Illustrations of Gahagan bifaces from the Gahagan Mound site in Northwest Louisiana. We are now looking at flake scar and beveling morphology associated with Gahagan biface retouch and refurbishment by Caddo knappers.

The post provides a preview of morphological similarities and differences associated with Gahagan bifaces found in Caddo burial contexts, which are currently thought to have been produced in central Texas. The preprint has been uploaded to SSRN and SocArXiv while the associated article is in review. Links to the SocArXiv preprint and other readings associated with this project are included below.

Preprint of 2019 article:

Selden Jr., Robert Z. and John E. Dockall. 2019. “A Comparison of Gahagan Biface Morphology across Caddo Features at the Gahagan Mound, George C. Davis, and Mounds Plantation Sites.” SocArXiv https://doi.org/10.31235/osf.io/fyw2d

2019 Conference poster:

Selden Jr., Robert Z., John E. Dockall, and Harry J. Shafer. 2019. “Lithic Morphological Organization: Gahagan Bifaces from Texas and Louisiana.” Stephen F. Austin State University, accessed March 1, 2019. https://scholarworks.sfasu.edu/crhr/266/

2018 DAACH article and preprint:

Selden Jr., Robert Z., John E. Dockall, and Harry J. Shafer. 2018. “Lithic Morphological Organisation: Gahagan Bifaces from the Southern Caddo Area.” Digital Applications in Archaeology and Cultural Heritage 10:e00080. https://doi.org/10.1016/j.daach.2018.e00080

Selden Jr., Robert Z., John E. Dockall, and Harry J. Shafer. 2018. “Lithic Morphological Organisation: Gahagan Bifaces from the Southern Caddo Area.” SocArXiv https://doi.org/10.31235/osf.io/u7qfr

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3D Geometric Morphometrics of Projectile Points – Populating Splines

 

As we continue to think through the various spline configurations (see previous post here), I have been constructing a number of models based primarily on the efforts of previous analyses for both 2D and 3D geometric morphometrics. While this is representative merely of a (very) humble beginning, experimenting with the reconstruction of configurations used in other analyses could help us to better understand how we might begin to move toward a replicable consensus configuration (certainly some great examples out there).

ZSpline_1

In this example, I am using the framework of two splines that were created as a 3D mesh sketch in Design X (above). I then added 10 equidistant sections (below) between the top and bottom of the projectile point. While those would most likely be cut where they intersect with the splines above prior to populating point data, I wanted to see where the–equidistant–points would populate along the various profiles.

ZSpline_4

In this case, it may work best to cut each of the 10 sections where they intersect either the exterior or interior profiles (or both), prior to populating the LM/sLM data. I did not populate the 10th section (very near the point of the projectile) for this example, simply because it was almost impossible to view the location of Point 2 (which is defined by the confluence of the vector and the poly-vertices of the mesh at the tip of the projectile) when that particular section was populated.

ZSpline_2

Another question that we will need to ask ourselves sooner than later, is where do we reach a point of saturation or diminishing returns with regard to the number of LM/sLM data points? There is still much left to think about, and we will continue to move toward the definition of a replicable consensus configuration as we work through replicating (as closely as possible) the numerous configurations that have been used in the past.

Our tactics differ from many of our colleagues, due primarily to our efforts to devise a configuration aimed at performing an initial “sort” at the assemblage level–different configurations would then be used for each of the identified categories based on more specific attributes. In the coming months, I hope to share some of our minor successes, and–no doubt–numerous failures as we continue to work toward a suitable configuration.

As always, your comments and constructive criticisms are welcome. You can comment by clicking on Leave a Comment below, or you can email me directly at selden3d@gmail.com. 

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