Multiproxy analysis of omnivore and herbivore coprolites: Inferences on Mid-Holocene dietary habits in Argentine Patagonia
Introduction
Coprolites produced by omnivores and herbivores represent a valuable source of information on past ecological and cultural interactions. Besides, plant fragments, pollen and silica phytoliths present in coprolites provide evidence of the variety of plants ingested by these animals. Omnivores can incorporate plants either directly (by consumption of different plant organs) or indirectly (by consumption of the viscera content of prey) (D'Antoni and Togo, 1974; Reinhard and Bryant, 1992; Rodrı́guez-de la Rosa et al., 1998; Alcover et al., 1999). Thus, the multiproxy analysis of coprolites may provide evidence of direct and indirect consumption of diet items and may thus help in reconstructing the ecological dynamics of past ecosystems.
Horrocks et al. (2003), for example, performed a multiproxy analysis of pollen, silica phytoliths and diatoms present in coprolites from Kohika, New Zealand, and found evidence of the diet, past vegetation, and seasonality in the use of sites, and corroborated the zoological origin of feces. Also, the multiproxy analysis of coprolites from various sources has generated information on past biological interactions, such as predator-prey relationships. Reinhard et al. (2007), for example, by analyzing bone remains present in human coprolites, found direct evidence of animal consumption. Bone remains, teeth and hairs of small mammals have also been found in coprolites of humans, foxes and dogs (Reinhard et al., 2003; Tolar and Galik, 2019).
Studies on plant inclusions in coprolites can not only provide evidence of direct consumption but also suggest evidence of indirect consumption (Alcover et al., 1999; Velázquez and Burry, 2019). Results of previous studies of our research group on plant fragments from coprolites of probable human origin found at the archaeological site Cerro Casa de Piedra Cave 7 (CCP7), Argentina, suggested that the presence of Poaceae leaves in the feces could be due to indirect consumption, by consumption of stomachs and/or intestines of camelids (probably Lama guanicoe) and their content (Martínez Tosto et al., 2016). In addition, multiproxy analyses (plant macro- and micro-remains) in coprolites of probable human origin have suggested evidence of consumption of different plants (Caruso Fermé et al., 2018). Other palynological studies of coprolites produced by hyenas (carnivores) have also suggested indirect consumption of pollen, through the consumption of stomachs and/or intestines of herbivores (Carrión et al., 2001; Pesquero et al., 2011), and/or consumption of water or food contaminated with pollen grains. More recently, Wood et al. (2016) pointed out that the presence of few pollen grains in coprolites from extinct dogs probably indicates indirect rather than direct consumption of vegetation.
In Patagonia, zooarchaeological studies of bone remains of camelids, particularly Lama guanicoe (guanaco), with processing and consumption marks by hunter-gatherer groups have allowed inferring past trophic relationships between omnivores (humans) and herbivores (camelids) (De Nigris, 2007; Fernández, 2017). The guanaco was one of the main resources for subsistence and material culture of hunter-gatherer groups that inhabited Patagonia from the late Pleistocene through to the Holocene (Miotti and Salemme, 1999; De Nigris and Mengoni Goñalons 2005; Borrero, 2013). However, foods of plant origin such as green leaves, fruits, and tubers were also important diet items in these human groups (Martínez Crovetto, 1982; Rapoport et al., 2003; Ciampagna and Capparelli, 2012; Molares and Ladio, 2014). For example, it is known that the guanaco feeds mainly on grasses and shrubs (Raedeke, 1978) and, in some cases, on trees when migrating into the forest during the winter (Bank et al., 2002). Different studies can also provide evidence on past predator-prey relationships. For example, it is known, that young guanacos may be prey of foxes (omnivores) such as Lycalopex culpaeus lycoides (red fox) and Lycalopex griseus (gray fox) (Novaro et al., 2009), whose diet consists mainly of small mammals, reptiles, arthropods and a low proportion of plant resources (fruits and seeds) (Johnson and Franklin, 1994; Zúñiga et al., 2018).
Multiproxy analysis of plant macro- and micro-remains present in coprolites and sediments from CCP7 have demonstrated the potential of this type of study to contribute to paleo-environmental reconstructions and to be a source of information on the resources used by hunter-gatherers (Caruso Fermé et al., 2018). However, the potential of coprolites multiproxy analysis to generate information on past dietary habits in Patagonia has not yet been investigated. Therefore, the aim of this work was to perform a comparative analysis of the content of plant fragments, pollen and silica phytoliths present in omnivore and herbivore coprolites from the archaeological site Cerro Casa de Piedra 5 (Perito Moreno National Park, Santa Cruz, Argentina), and discuss the potential to infer Mid-Holocene dietary habits in southern Patagonia.
Section snippets
Archaeological site
Cerro Casa de Piedra (CCP) (47°57′S; 72°05′W) is located at 900 m a.s.l. and at 400 m from the southern bank of the Roble River, close to its origin in Burmeister Lake (Fig. 1). This volcanic hill is characterized by several caves and rockshelters, including Caves 5 (CCP5) and 7 (CCP7), which present a large amount of archaeological evidence. Palynological analyses of sediments from CCP5, dated earlier than 7402 cal years BP, have shown vegetation changes reflecting more arid and colder
Coprolites
In the present study, we analyzed coprolites recovered from archaeological layer 4. Based on their morphological characteristics and contents (macro-remains), four of them, designated as samples M24, M44, M47 and M50, were assigned to omnivores (human/canid coprolites), according to Jouy-Avantin et al. (2003). We also analyzed other four coprolites in good preservation condition, designated as 452.1, 452.2, 452.3 and 452.4, which, according to their morphology, were assigned to herbivores
Human/canid coprolites
The human/canid coprolites were in good condition, had a diameter between 21 mm and 32 mm, and had brown-dark, brown-ochre and brown-green color (Fugassa, 2006). Their macroscopic analysis under the stereo binocular microscope showed macro-remains of different origins (Table 1), as well as traces of charcoal, animal hairs, leaf remains, seeds, small sections of stems and sclereids. Optical microscopy showed that the animal hairs, found in M44 and M47, corresponded to Lama guanicoe and rodents.
Discussion
The plant fragments, pollen and phytoliths found in coprolites could be the product of past trophic relationships between organisms (plants-herbivores-omnivores) and can provide information about direct and indirect diet components. Within indirect components, these proxies may also evidence past trophic relationships and interactions between living organisms and their environment, including the decisions made for foraging, the closeness and quality of food and water sources, the exposure to
Conclusions
The multiproxy analysis here performed on pollen, silica phytoliths and plant fragments found in coprolites allowed us to determine different diet items of camelids and omnivores. This analysis also led to a higher taxonomic resolution in the identification of some diet items, for example species of the family Poaceae, and revealed similarities and complementarities, in some cases, in the composition and abundance of indicators, all of which allow the proposal of new hypotheses that may help to
Author contributions
Velázquez Nadia: Conceptualization, Methodology, Formal analysis, Investigation, Writing - Original Draft preparation, Writing - Reviewing & Editing, Funding acquisition; Martínez Tosto Cecilia: Conceptualization, Methodology, Formal analysis, Investigation, Writing - Original Draft preparation, Writing - Reviewing & Editing. Benvenuto María Laura: Formal analysis, Investigation, Writing - Original Draft preparation, Writing – Reviewing & Editing. Fernández Natalia: Writing – Reviewing &
Data availability
The data that support the findings of this study are available from the corresponding author.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
We thank Carlos Aschero and his Research Team for providing the samples for this study. Funding: This work was financially supported by Agencia Nacional de Promoción de la Investigación, el Desarrollo Tecnológico y la Innovación [PICT 2015 No. 2541; PICT 2017 No 0455, No 3239] and Universidad Nacional de Mar del Plata -SECYT [EXA 754/2016–2017 and EXA 855/2018–2019], Argentina.
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