Christopher J. Jurgens is an Affiliated Researcher with the Texas Archeological Research Lab. An excerpt of this article appeared in the December 2017 TARL Newsletter.

In 2014, Dr. Steve Black requested that I dust off my ‘research hat’ when I retired after a career in state government.  As with my own academic beginnings, Steve was a product of the undergraduate Archaeological Studies program at UT-Austin in the 1970s.  Dr. Black worked at the Texas Archeological Research Laboratory (TARL) after completing his Ph.D. at Harvard University before becoming a professor in the Anthropology Department at Texas State University.

My doctoral research focused on the Lower Pecos cultural region of the Texas borderlands and was completed in 2005.  TARL’s prolific and well-preserved collections from Arenosa Shelter (site 41VV99) formed the basis for my research (Jurgens 2005, 2008).  Bone preservation in the region’s dry rockshelters is typically very good, especially for sites with cultural materials in Holocene-age contexts.  Remember Ezekiel’s Biblical message about dry bones? As an analogy to this prophet’s ancient words, bone fragments ‘come alive’ to help us understand the prehistoric cultures in this region and, increasingly, in other regions of Texas.

Black’s “come visit” invitation came nearly a decade after completing my Ph.D. at UT-Austin.  Dr. Black invited me to join his Ancient Southwest Texas (ASWT) project research team at Texas State University, adding my research specialties of zooarchaeology and bone technology to the team.   Since then, I’ve also worked with the Center for Archaeological Studies (CAS) at Texas State University.  At CAS, I am conducting similar research for a data recovery project at the Spring Lake site in San Marcos and smaller, historic period sites in San Antonio.

Zooarchaeologists study animal (aka, faunal) remains from archaeological sites using a specifically anthropological standpoint instead of a biological or paleontological perspective (Reitz and Wing 2008).  Zooarchaeological faunal studies are also used to investigate site formation, biological processes, and cultural processes that are reflected in the particular collection (or sites) being studied.  The anthropological perspective addresses the complex interaction between humans, their environment, and the consequences of that relationship. Animal bone fragments are analyzed to identify the animals and eco-niches represented and any human modification from subsistence or bone technology activities.  Analyses begin with sorting of bone fragments into groups, based on size of animal, skeletal element, signs of burning, or other obvious evidence of butchering, skinning, or technological modification (Figure 1).

Figure 1: Bison bone fragments from Eagle Cave (41VV67, Feature 14 in basal deposits) near Langtry in the Lower Pecos region being sorted before consolidation and analysis.

As a zooarchaeologist, an important question that I must answer during research is how faunal remains enter archaeological contexts.  Are the faunal remains there strictly as a result of natural processes? Are the faunal remains spatially associated with cultural materials?  Context of faunal remains is the key to understand their role in any site.  If the faunal remains are spatially associated with cultural materials, then the zooarchaeologist must ask additional questions.  Have the faunal remains been modified by cultural behaviors processes (skinning, butchering, tool manufacture or use, bone breakage for marrow removal or bone grease production, etc.)?  If so, then the cultural filter has played a role in how the faunal materials were placed in the site. The bone fragments shown in Figure 1 are from an extinct bison recovered during 2016 excavations at Eagle Cave (41VV167) by Texas State University (Castañeda, et al. 2016). They reveal a late Paleoindian cultural filter through remnant evidence of intensive butchering.  The bison’s mandible had many cut marks resulting from muscles being cut to allow the tongue to be removed (Figure 2).  Ethnographic analogy from historic period bison hunters in the North American Great Plains mirrors this prehistoric evidence—the tongue was a prized portion of meat.  For thorough discussion of this topic and related literature, see Jurgens (2005, Chapter 3).

Figure 2: Right mandible fragment from intensively butchered extinct bison recovered during 2016 excavations at Eagle Cave (41VV167).

One reason zooarchaeological studies are important in archaeological projects is that they help us understand past environments.  Some animals only thrive in certain ecological conditions, such as upland grasslands or streamside woodlands.  Groups of animal bones from the same archaeological context allow archaeologists to infer about paleo-environmental conditions during the time period when those deposits were formed.  For example, let’s consider the presence of both jackrabbits and swamp rabbits in the same strata in archaeological sites along the southern edge of the Edwards Plateau.  These fragments point to prey being targeted in both dry and moist environmental niches by prehistoric hunters and gatherers.

Let’s go back to the saga of my post-retirement research.  Following Steve Black’s invitation, I joined the ASWT project’s collaborative team.  The ASWT project team is researching sites in Eagle Nest Canyon near Langtry in the western Lower Pecos cultural region. Incorporating the Eagle Nest Canyon data sets from the Eagle Cave, Skiles Shelter, and Kelley Cave collections allows them to be compared with that from Arenosa Shelter.  Eagle Nest Canyon joins the Rio Grande about 15 miles west of Arenosa Shelter’s location on the Pecos River near its confluence with the Rio Grande.  The Ancient Southwest Texas Project study allows me to link my Arenosa Shelter research to the ongoing Eagle Nest Canyon efforts.  The linkage expands our understanding of life-ways in the western Lower Pecos cultural region and elsewhere in Texas.

Analytical comparisons between Arenosa Shelter and the Eagle Nest Canyon sites have been focusing on Late Archaic and Late Prehistoric bone technology and subsistence economies.  Most Eagle Nest Canyon sites lack the deeply stratified deposits present in Arenosa Shelter.  In my view, this distinction is moot. As shown by my earlier Arenosa Shelter study, sixty per cent of faunal materials and bone artifacts were found in upper deposits (strata 4 – 9) with a Terminal Late Archaic context dating between about 2,300 and 1,300 years ago.  Late Archaic and Late Prehistoric faunal materials had good to excellent bone preservation, as did those in Paleoindian deposits.  Arenosa Shelter’s Middle and Early Archaic deposits (strata 12 – 36) were heavily damaged by high energy Pecos River flooding.  Most of the bone fragments that these deposits may have originally contained were removed, especially those from smaller animals.  Remaining bone in these strata also quite often has been redeposited in secondary context.

Faunal analysis utilizes techniques I’ve applied over the past 20 years.  Using standard zooarchaeo­logical procedures, skeletal materials from reference specimens of fish, birds, and mammals were used to identify the archaeological faunal material, assigning it to the most appropriate taxonomic group.  Some of the reference specimens were loaned from the UT-Austin Jackson School of Geoscience’s Vertebrate Paleontology Laboratory.  Assignment of bone fragments to the most appropriate taxonomic group requires an understanding of bone structure and skeletal anatomy of all potential animal groups, from fish and reptiles to birds and mammals.  Some of the bones are easy to identify, based on their structure and morphology.  Distinctive features allow identification of bone fragments to specific animal form and portion of skeletal element.  For example, the archaeological and reference specimen bones in Figure 3 are both identifiable as feet bones from species in the rabbit family.

Figure 3: Comparison of archaeological specimen of cottontail rabbit foot bone and modern jackrabbit specimen from Jurgens reference collection.

Microscopic examination of bone fragments is used to verify taxonomic and skeletal element assignment, especially for smaller animals.  It is also used to search for cultural modifications that may be present on fragments.

Microscopic examination uses a 10x-25x binocular microscope (Figure 4). Specialized lighting includes an overhead general light and a low sidelight low that increases contrast (Figure 5).  The sidelight reveals changes to the bone surface. Butchering damage and technological modifications made during tool or ornament manufacture and use each leave distinctive traces on the surface of bone.  The human modification may be the form of cut and chop marks, scrape marks, grinding, surface polish, and microscopic striations from use-wear.  Carnivore damage and root-etching also modify the bone surface.

Figure 4: Bone fragments being examined microscopically during faunal analysis.
Figure 5: Specialized lighting used during microscopic examination of faunal materials.

The fauna from Eagle Nest Canyon sites parallel those from Arenosa Shelter.  They appear to contain very similar faunal remains, including those of small to large mammals, fish, birds, turtles, and other reptiles. Bone preservation is variable in both locales, dependent on site formation processes and post-deposition effects of moisture on bone within the strata. The moisture present is from groundwater exiting from bedrock seeps or is from rainwater funneled from the canyon rims above the sites.

Many bone fragments showed signs of butchering or cooking by the site’s inhabitants. Skinning and butchering leave distinctive cutmarks, as does dynamic bone breakage to remove marrow.  The bone flake from the Spring Lake site in Central Texas is a good example of a result from cultural activities to harvest bone marrow during butchering (Figure 6).  Similar bone flakes are found in the Lower Pecos cultural region and elsewhere in Texas.

Figure 6: Side view of bone flake from artiodactyl leg bone found during Spring Lake Data Recovery Project faunal analysis, with impact mark and fractures showing breakage for marrow harvesting.

Some of the faunal remains and bone artifacts from the Eagle Nest Canyon sites have been burned, mirroring those in Arenosa Shelter.  Two patterns of burning are evident—roasting and disposal.  Direct heat cooking, such as grilling or roasting, leaves distinctive discoloration of bone fragments where bone was not covered by meat during cooking. The disposal pattern of burning is hypothesized to represent burning of food remains or incorporation of remnant bone into earth oven fill. Sometimes, discard pattern bone has been burned so intensely that most organic matter is removed from the bone. Bones incinerated by heat over 850o F caused this condition termed calcination.  Similar patterns are being documented in analysis of the fauna from the Spring Lake site.

The Eagle Nest Canyon/Arenosa Shelter comparisons have allowed me a clearer understanding of the western Lower Pecos cultural region.  The concurrent analysis of the Spring Lake faunal material is extending that knowledge to the eastern edge of the Edwards Plateau.  My research has documented 1) eco-niches targeted by the prehistoric inhabitants, 2) specific subsistence behaviors (e.g. filleting of fish, specific cuts to overcome defensive pectoral fin spines in catfish, and specialized skinning of mammalian carnivores), and 3) manufacturing and use of tools or ornaments from boney subsistence remnants.

A wide variety of formal bone tool and ornament types have been recorded, as have the manufacturing processes for them.  Evidence of manufacturing processes included scrape marks made to remove the periosteum layer from the bone surface; distinctive grooves cut to facilitate controlled snapping of the bone into segments; scraping and grinding to shape tool or bead preforms; and wear left by contact with plant materials, hides, or other substances during use.

Most formal tools were made from deer lower leg bones (Figures 7-9).  Other skeletal elements of deer were also used to manufacture formal tools, such as the ulna or antler times (Figure 10).  In addition, bones of smaller mammals formed the raw material for tool manufacture, as did the pectoral fin spines of catfish (Figure 11).  Informal expediency tools are rare, but manufactured from large mammal long bones during butchering and retain use-wear from meat, sinew, or hide (Figures 12 and 13).

Figure 7:  Arenosa Shelter (41VV99) spatulate tool manufactured from deer lower leg bone.
Figure 8: Bone tool fragment from Spring Lake Data Recovery Project faunal analysis showing grooving used to detach tool blank from deer or antelope long bone.
Figure 9: Fragment of Early Archaic bone tool from Spring Lake Data Recovery Project with manufacturing evidence and use-wear from silica-rich plants.
Figure 10: Deer ulna spatulate tool from Arenosa Shelter (41VV99).
Figure 11: Catfish pectoral spine tool from Arenosa Shelter (41VV99).
Figure 12: Bone expediency tool from Arenosa Shelter (41VV99).
Figure 13: Fragment of informal bone tool from Spring Lake Data Recovery Project with grooving used to detach tool blank from long bone. Narrow end has use wear from hide working.

In my research, I have adopted a bone tool typology based on tool morphology, supplemented with use-wear analyses to document the actual function. Many bone tools from the Lower Pecos cultural region have been mistermed “awls” in the literature, implying function based on the tool form. The morphology of these tool’s cross-section is generally flat and ovoid.  The main differences are in the tip (distal) section.  Measurements of width and thickness at and near the tip are used to assign the tools into types. Use-wear analysis is then conducted to determine actual function.  Use-wear studies revealed that those tools were used by prehistoric inhabitants to extract other resources from the environment or to manipulate them. Hides, desert succulent fibers, meat, wood—wear from all of these were revealed on tools or tool fragments through microscopic examination.

Figure 14: Bone bead from Eagle Nest Canyon sites in Lower Pecos.

Beads were manufactured from bird or small-medium mammal long bones, with hawk and rabbits being the most common source animals (Figure 14).  A Eureka! moment in my research came when I recognized that long bone ends from these animals retained evidence of being cut off during bead manufacture.  Linking bead cross-section to morphology of the cut-off bone ends allowed identification of species that were the most common source animals (Figure 15).

Figure 15: Bone bead manufacturing debris from Arenosa Shelter (41VV99).

During the on-going Spring Lake Site faunal analysis, I’ve noticed many parallels to the Lower Pecos study results, especially in the presence of bone technology remnants. The Spring Lake site shows that the same processes used to make the tools and ornaments in the Lower Pecos were in use in Central Texas by the Early Archaic.

One problem that I’ve come to face in the Spring Lake site study is that bone tool or ornament fragments, and evidence for their manufacture, have rarely been recognized or documented in Central Texas.  Part of that scarcity is due to the differences in site types between the Lower Pecos and Central Texas. Fewer dry rockshelters are present in Central Texas.  Bone preservation in the clay soils of Central Texas is another problem. Mechanical crushing is caused by movement in the region’s expansive clay soils. Overall bone fragment size of archaeological faunal remains in Central Texas is much smaller than in the Lower Pecos.

A separate problem is the lack of trained zooarchaeological specialists.  This problem can be addressed by appropriate interdisciplinary education in university archaeological programs. I was fortunate during my undergraduate and graduate education to be trained by paleontologists and zooarchaeologists.  These dedicated educators continue to mentor me even near the end of their careers or in retirement.  Following their examples, I am mentoring the current generation of students. Training in zooarchaeological methods is no different than training in lithic or ceramic analytical methods.  Unless students are taught the methods, how can they identify animals represented in archaeological sites, much less recognize the signals of bone technology amongst the subsistence debris?

Sites such as Arenosa Shelter, the Eagle Nest Canyon sites, and the Spring Lake site help us open doors onto the past.  Once we throw those doors open, we can begin to understand how prevalent and widespread cultural processes, such as bone technology, were in prehistory across Texas.

Ezekiel’s right: we archaeologists must open our eyes and minds to the dry bones that help us understand the remnants of prehistoric cultures that surround us.

References Cited


Castañeda, Amanda M., Christopher Jurgens, Charles W. Koenig, Stephen L. Black, J. Kevin Hanselka, and Haley Rush

2016 “Multidisciplinary Investigations of a Paleoindian Bison Butchery Event in Eagle Cave.” Paper presented at the 87th Texas Archeological Society Annual Meeting.  Nacogdoches, Texas.


Jurgens, Christopher J.

2005 “Zooarcheology and Bone Technology from Arenosa Shelter (41VV99), Lower Pecos Region, Texas.” (http://repositories.lib.utexas.edu/handle/2152/1586).  Unpublished Ph.D. Dissertation.  Department of Anthropology.  The University of Texas at Austin.


2008  “The Fish Fauna from Arenosa Shelter (41VV99), Lower Pecos Cultural Region, Texas.”  In:  Joaquín Arroyo-Cabrales and Eileen Johnson, Guest Editors, Contributions to Latin American Zooarchaeology in Honour of Oscar J. Polaco, Fryxell Award Recipient for Interdisciplinary Research. Quaternary International 185:26-33.


Reitz, Elizabeth J. and Elizabeth S. Wing

2008 Zooarchaeology (Second Edition).  Cambridge Manuals in Archaeology. Cambridge University Press, Cambridge, U.K.


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