Fauna
What do fauna remains tell us?
Animal bone remains provide valuable information about their use by humans in the past.
Zooarchaeology (or archaeozoology) is the branch of archaeology that studies the way in which humans used animals, through the remains of fauna.
What are the main archaeofaunal analyses?
The faunal analyses are mainly two:
1. Analysis of the Agents Involved in the Formation of the Record
These analyses are also called "taphonomic studies" and allow us to evaluate the degree of intervention of humans, carnivores, rodents, plants and even water in their accumulation. Thanks to them we know, for example, if the animals were used by carnivores and/or humans and in what order this use occurred.
These analyses allow us to know which animals were consumed and how they were consumed. They answer questions such as: which animals did humans process? Did they only use their meat or also resources such as their skin, tendons or bones? Were there changes in the processing of animals? Why? This type of study is based on the quantification of the different animal species, on the differential representation of their bones and on the observation of the distribution of cut and percussion marks on the bone remains.
Faunistic analysis in the upper basin of the Santa Cruz river
Faunistic studies carried out in the south of the upper basin of the Santa Cruz river have been based mainly on the analysis of two sites: Chorrillo Malo 2, currently located in the forest-steppe ecotone, and Río Bote 1, located 70 km away from the first, in the steppe east of Lago Argentino.
At both sites, studies on the use of animals suggested that the guanaco was of primary importance in the lives of hunter-gatherers throughout the time they were in this space.
What resources did human groups obtain from the guanaco?
These groups obtained from the guanaco: meat, marrow and bone fat for consumption, skins for making clothes, tendons and even bones for making instruments.
The cut marks on the middle part of the bones indicate that they were stripped. On the other hand, the presence of cut marks on the ends suggests disarticulation and the extraction of tendons. Finally, the evidence of blows on bones indicates the extraction of marrow and the fat inside. In the case of Río Bote 1, even instruments made from guanaco bones have been recovered.
What do we know today about subsistence in the area?
We know that from at least 7.000 years ago until 450 years ago, hunter-gatherer groups in the area based their diet mainly on guanaco meat - which they consumed fresh and sometimes dried -, the marrow inside the leg bones and, in some cases, the fat from the bones of the body.
However, the guanaco was not always used in the same way. The data indicate that its processing would have varied depending on the environmental conditions, which influenced the nutritional status of the prey and, consequently, affected the human groups. For example: in Río Bote 1 it was observed that, during arid periods, even small bones such as the phalanges were processed to obtain the fat inside.
Furthermore, animal consumption would also have varied depending on the way the space was used. For example, both in Río Bote 1 and in Chorrillo Malo 2 approximately 4.000 years ago – when there were already people using different environments in this area – the use of all the resources provided by the guanaco and an increase in the intensity of its processing was recorded. This was probably due to the fact that there were more people in the area and, consequently, there would have been an increase in the need to more intensively use the resources provided by each animal. Thus, thanks to this research we were able to see how ancient inhabitants would have reacted to changing environmental circumstances.
Faunistic analysis in the Chico river basin
Archaeofaunal studies are currently being carried out at several sites located south of the Deseado Massif. These analyses aim to investigate the subsistence of hunter-gatherers in relation to environmental variations and the movements of the human groups that frequented these spaces.
Our data, combined with those previously obtained by Aguerre and Durán, indicate that the guanaco would have been the main resource used by human groups in this area.
Furthermore, in sites in this area such as La Gruta 3, remains of extinct animals such as Mylodontino (a species of giant sloth) have been recorded, dating back at least 9.500 years. We are currently investigating both the reasons why the remains of this animal were found in this site, and whether or not these animals were processed by hunter-gatherer groups. To do this, we make 3D models of the bones belonging to specimens catalogued as extinct fauna, which allow us to make systematic measurements of the traces observed on the bone surfaces. In this way, we build a catalogue of traces and measurements that in the future will allow us to evaluate the existence of processing of Mylodontino by hunter-gatherer groups in this space.
3D models as an exploratory methodology in the analysis of linear marks on bone remains
This technique determines the geometric properties of an object and its position from photographs. It is an easy-to-use tool and is partially automated. It is also inexpensive compared to other specialized tools.
Once the photographs (A) were taken, they were loaded into the 3D modeling program. The processing began with the alignment of the photographs to obtain a sparse point cloud. Then the dense point cloud (B) was built and scaled and, based on the depth maps, the 3D solid model, the 3D model with texture and orthophotographs (C) and the DEM (D) were built. As a result, we were able to obtain 3D models and DEM models that can be measured in any Geographic Information System (E).
1) Photo alignment and sparse cloud construction
- Automatic camera optimization
- Gradual elimination of sparse matching points
2) Dense cloud construction
3) Elimination of low confidence points if any
4) Model scaling
5) 3D model construction
6) DEM construction
7) Orthophoto construction
On the rib of Milodontino with possible cut marks: References: Red rectangle top right: sector where the marks are located. From right to left (1,2,3,4): common photos with projection of leftovers showing at least four linear, superficial, oblique, medium and short length marks (5) root mark of a plant.
Median phalanx of Mylodontine: taking photographs with shadow projection allowed us to see a short, deep, transverse, linear imprint on the palmar surface of the distal epiphysis. Accompanied by thinner imprints on the opposite surface of the phalanx.