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

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.

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.

Selden Jr., Robert Z., John E. Dockall, and Harry J. Shafer. 2018. “Lithic Morphological Organisation: Gahagan Bifaces from the Southern Caddo Area.” SocArXiv


Geometric Morphometrics and a 3D Caddo Vessel from the Sam Kaufman Site at SMU

While yes, this post contains a great interactive figure of an incredible Caddo vessel from the Sam Kaufman site (curated at Southern Methodist University #SMU), I wanted to take a moment to bring us full-circle, and return to the reason that I am scanning all of these vessels. Some time ago, I began getting fascinated by the high degree of variability in Caddo vessel shape and size, and have since also noticed some degree of variation in asymmetry.

At the same time that my interest in this topic began to increase, I also quickly realized just how much room for growth that there was in terms of applying geometric morphometrics to archaeological problems. It took time to get through the literature; and I kept finding new articles and book chapters listed in the references of my readings that had escaped the reach of my initial literature review.

Since I had been tinkering with social networking, I reached out to a colleague to assist me in building a citation network. That network has since been completed, and proved to be an invaluable asset in terms of not only centralizing the archaeological literature associated with geometric morphometrics, but it helped me to identify those works in the geometric morphometric literature that are most often cited (InDegree) and most important (identified using Google’s PageRank algorithm) to the overall network (click here to view the interactive network).

Directed bipartite citation network for studies of geometric morphometrics in archaeology.

Having made my way through the literature, I began to think through the various methods of landmark and semilandmark applications that were available (based on the numerous research questions that could be asked of these data), and quickly found that the configurations were really only limited by my 3D modeling abilities. At that point, I ventured up to Lakewood, Colorado to spend some time working with the crew at Geomagic, where I learned how to use and employ the various features of Geomagic Design X and Control X (more here). Using these tools, I was able to devise a method of applying landmarks in a replicable manner using reference geometry that was built around the 3D mesh of the ceramic vessel. This first iteration of the landmark and semilandmark configuration worked very well for addressing some of my initial questions (see that in the video below).

From here, things began to get more complex. In October of last year, I headed to Portugal for what would be an important transitional period for my work; learning how to write scripts for, and run the various analyses in, the geomorph package in R. This opened something of a Pandora’s box for me, from which it is very likely that I will never fully recover. Needless to say, shape, form, allometry and asymmetry shifted quickly from a peripheral interest to something of a primary project.

Procrustes superimposition of landmarks and sliding adaptive semilandmarks used in the analysis of Caddo ceramics.

Since then, there have been dozens of iterations and developments in my landmark and semi-landmark configurations and analyses; many of which (particularly those associated with my morphological integration inquiries) are actively evolving. I was fortunate to receive funding for much of this work through the National Center for Preservation Technology and Training (NCPTT); a group that I have really enjoyed collaborating with.

As you interact with this vessel from the Sam Kaufman site, consider where (and how) you would apply landmarks/semi-landmarks to the 3D surface.

In terms of theory, analyses of geometric morphometrics can be couched within several interesting anthropological lines of inquiry that include, but are not limited to, (1) identifying the locus of a specific innovation, (2) the spatial and temporal dynamics of morphological variation for specific elements (neck, body, base, etc.) of ceramic design, (3) identifying or refining social networks used by specific Caddo polities/groups during temporal periods previously defined—primarily—through design-based seriations, (4) intra/inter-polity/group variation of shape, form, allometry and asymmetry for ceramic design, (5) potential trade relationships based upon the presence of a specific shape/form of vessel outside of known (assumed) social boundaries, and (6) the power or influence that shifted among and between polities through time. These considerations could be woven into discussions of communities of practice, craft specialization, ceramic technological organization, politics, religion, and—possibly—inter/intra-polity disputes and warfare. Furthermore, this research design has the capacity to inform greatly upon the evolution of ceramic design as it relates to the shape, form, allometry and asymmetry that occurs in Caddo vessels, and by adding the related qualitative measures to our results we might just have the potential to bolster evidence for human behaviors associated with ceramic production and use within the larger ancestral Caddo territory.

Historic era (1680+) Caddo networks based upon ceramic types (as I tip my hat to Dr. Timothy K. Perttula). Incorporating elements of vessel shape, form, allometry and asymmetry may help us to further refine this current iteration of the Historic Caddo network.

Initially a development in the biological sciences, the study of geometric morphometrics in archaeology will no doubt include some interesting discussions regarding the various analytical and theoretical components that are most appropriate for a cultural system versus a biological system as we continue to press forward. There remains plenty of thinking left to do on this subject, but based upon the preliminary results, the capacity for geometric morphometrics to inform upon issues related to material culture and cultural systems could be enormous.

The very humble beginnings of exploring directional and fluctuating asymmetry in Caddo vessels.

Beyond the realm of empirical geometric morphometric studies, lies the domain of theoretical morphospace. Biologists have gainfully used theoretical morphospace to aid in clarifying issues of morphological change through time. They have done so by aggregating the results of geometric morphometric studies–a dialogue which would seemingly fit very well within the scope of anthropological and archaeological inquiry. By definition, theoretical morphospace represents the full range of possible morphologies for a group of artifacts; allowing investigators to posit, and contemplate, more- and less-adaptive morphologies (similarities and differences). It is within discussions of theoretical morphological transitions where I see the greatest promise for geometric morphometrics in archaeology; an ambit of inquiry in which the skeleton trees and topological properties of the artifacts tell us a much more dynamic story with regard to the progression of a particular shape (bottle, bowl, olla, etc.) through time. Within the context of my own long-term research design, theoretical morphospace seemingly holds much promise, and may represent the approach needed to identify, unlock and unpack a ceramic morphological transition that remains hidden in the various vessel shapes once employed by Caddo potters.

So, while the 3D images are fun to interact with–and have any number of preservation, access and outreach perks–my intention is to use them to bolster our discussions of shape, form, allometry and asymmetry in Caddo ceramic studies, and to use that evidence to posit a number of novel insights into the highly variable and dynamic prehistoric landscape that the Caddo people once commanded.

Many thanks to the Caddo Nation of Oklahoma and Southern Methodist University (Dr. Sunday Eiselt in particular) for the requisite permissions and access needed to scan this important artifact from the ancestral Caddo territory, and to present the 3D model here in color.


robert z selden jr, archaeology, archeology, geometric morphometric, ceramic, analysis, mathematics, statistics, 3d, 3d scan, laser profilometer, optical profilometer, incision, morphology

Laser Profilometry/Ceramics

I was recently afforded the opportunity to visit the National Center for Preservation Technology and Training (NCPTT) in Natchitoches, Louisiana to explore possible uses of profilometry for our 3D research of Caddo ceramics. After manipulating various settings and tweaking scan resolutions, we scanned an arbitrary 1.5cm square on an incised Caddo sherd from 41SY280 (41SY280-17; above and below – sherd courtesy of the United States Forest Service). Those results have provided plenty of food for thought; particularly for morphometric attributes associated with Caddo decorative elements.


The image below is of a single 1.5cm surface profile, and the four large dips seen there are incisions that a Caddo maker scored into the surface of the clay body; likely during the Late Caddo period (ca. 1450-1680) in East Texas.


One of the many useful features of the software is that it can rapidly quantify variation in the scanned surface. The image below depicts the results of that quantification when using the default settings. While I would argue for some modifications to this prior to employing those metrics in an analysis, it did make for some interesting discussions about variation in Caddo decorative elements.

So might it be possible to use this technology to better segregate between the decorative elements (engraved, punctated, incised, trailed, etc.) used by Caddo potters? Maybe. It might also help to better characterize variations in tool use by Caddo ceramicists as they sought to create (and replicate?) specific design elements.


Profilometers are not newcomers to archaeology and have been used in both historic and prehistoric applications (mainly physical properties [primarily topography] and use-wear on lithics), and a review was recently published discussing experimental studies of lithic use-wear.

In terms of ceramics, there was a recent study of Roman pottery graffiti that employed a profilometer.

This has left us with plenty to ponder in terms of the morphological attributes associated with Caddo decorative elements, and I hope to return to NCPTT in the near future to begin working to parse those out.


Many thanks to Jason Church and Tad Britt at NCPTT for taking the time to explain the various aspects of the hardware and software, and for allowing time on the profilometer.

Thanks also to Juanita Garcia and the United States Forest Service, who provided the Caddo sherd from 41SY280 that was scanned with the profilometer, and used in this post.


References made to published literature are hyperlinked within this post above the animation. Link to those by clicking on the bold/color text.



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Make 3D Cardboard Models of Caddo Ceramic Vessels!


Among the many topics that we have breached of late has been how to best augment our 3D scanning, documentation and analysis efforts with an educational component. One promising method of doing this is through the creation of (cut-out) cardboard models. This is an inexpensive process that we encourage you to try. To create the model, we used a 3D scan of a Caddo ceramic vessel in the Texas Parks and Wildlife Department’s collections from 41WD60 in Wood County, Texas (see more about this vessel here).


Using CAD-based software, we modeled the vessel and produced three easy-to-assemble cardboard reproductions that can be created by printing the .pdf’s provided in the text of this post, and simply gluing those printed pages (8.5 x 11″) to cardboard and cutting them out. Each of the slices has a number associated with it that corresponds to the adjoining piece. The first of these was created as a radial model, and produces the basic vessel form. To download the cardboard version of the radial model of the vessel, click here –> TPWD_41WD60_1976.31.7_RadialCardboard


Virtual model–center–and fabricated model–bottom left. Fabricated model made from an old moving box in our attic. Click to enlarge.

In addition to the radial model, we also created a horizontal model that can be glued together, one piece at a time by lining up the blue dots on the template pages (download directions for the horizontal model here –> TPWD_41WD60_1976.31.7_Cardboard


Future plans include exporting these designs to a laser cutter, where we can begin to incorporate different materials, like plastic (below), which may allow us to better view the design elements as well as the vessel’s shape (at least where those designs have a vertical and horizontal component).


Of course, it is also possible to build these models purely for fun – which is why we’re also providing you with plans to make a cardboard Caddo effigy vessel. This particular piece is curated at the Texas Archeological Research Laboratory (TARL) from 41UR2 (click here for the tempate –> TARL_41UR2-23 here.


We hope that you will make some time to build one (or all) of the models provided in this post while pondering the rich history associated with these designs, and we encourage you to share them with your family as well as your students and peers. In the meantime, we will continue experimenting with the various educational potential that our 3D scans can provide, and will pass along more possibilities as they become available.

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