CONICET | Buscador de Institutos y Recursos Humanos

In this paper we study the relationships between plants and extinct megafauna by examiningthe characteristics of the vegetation in the central region of Argentina (i.e., Espinal, Monte andChaco phytogeographic regions). First, we study the size, shape, quantity, and characteristics offruits and seeds. We also evaluate the presence of mechanical (spinescence and wood density) and chemical (secondary metabolic compounds) defenses against high rates of herbivory. Complementarily, we assess the importance these plants had for human populations, usingarchaeological, ethnographic, and current data. A high percentage of the analyzed plants metthe criteria proposed for fruits and seeds dispersed by megafauna, together with a highfrequency of spinescence, high density woods and secondary metabolites. We propose thatthese traits cannot be explained by the herbivory pressure of extant fauna in the area, but ratherdeveloped in interaction with currently extinct fauna. We suggest that Pleistocene megafaunal extinction had important consequences in the region due to their role as ecosystem engineersand to vegetation´s characteristics, which were probably strongly shaped by megafaunaactivities. Among these consequences, we discuss the loss of certain interactions between theseanimals and vegetation, such as loss of seed dispersal mechanisms, shrub invasion, andincreased susceptibility of vegetation to fire. Other effects for hunter-gatherer groups were thegeneration of highly regulated mobility patterns and the formation of barriers for the dispersalof prey. Finally, we also discuss the importance of these plants for human populations as food,construction material, medicines and firewood. Likewise, the role of humans as "heirs" of the megafauna in the propagation of tree and shrub species is highlighted.

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