Reply to “Comment on “Isotopic insight on paleodiet of …” by Bocherens et al. (Gondwana Research, 48(1), 7–14)”

Abstract

Fariña and Varela (2018) consider that the observed pattern of differencebetween δ13C in the carbonate fraction of bioapatite and bonecollagen (Δδ13Ccarb-coll) presented for extinct giant Xenarthrans, especiallythe giant ground sloth Megatherium, do not demonstrate an herbivorousdiet, as concluded by Bocherens et al. (2017). The mainargument is that the influence of body mass on Δδ13Ccarb-coll valueswould not have been considered in Bocherens et al. (2017). However,contrary to the assertion by Fariña and Varela (2018), the possible influenceof bodymass on Δδ13Ccarb-collwas actually considered in thiswork.Indeed, small and large herbivorous as well as small and large carnivorousmammals were considered separately among the modern mammalsused as reference to compare the fossil specimens (Fig. 2 andTable 2 in Bocherens et al., 2017). Small and large carnivores on theone hand, and small and large herbivores on the other hand, presentedstatistically significant differences. Despite these differences linked tosize, small herbivores and small carnivores presented statistically significantdifferences (p b 0.0001), as did large carnivores and large herbivores(p = 0.008) (Table 2 in Bocherens et al., 2017). Therefore, thepossibility to infer dietary preferences from Δδ13Ccarb-coll in each sizeclasswas checked onmodern specimenswith known diets before inferringthe paleodiet of extinct Xenarthrans using the same approach.