Tooth tales told by dental diet proxies: An alpine community of sympatric ruminants as a model to decipher the ecology of fossil fauna

Abstract

Paleobiologists tend to use dietary information as an ecological indicator because diet is a fundamental link between an organism and its environment. However, the ecological information from fossilized hard tissues is often difficult to interpret, because links between environment, diet, and hard tissue biology are insufficiently studied in modern communities. To address this dilemma, we investigated dietary proxies commonly used by paleobiologists in a 4-ruminant community from the French Alps. Dental microwear textural analyses are applied to 82 specimens of roe deer, red deer, chamois, and mouflons. Intra-tooth serial enamel stable carbon and oxygen isotope analyses of the structurally bound carbonate were applied on eleven specimens, with isotope-based niche reconstructions, and inverse modeling of original seasonally variable oxygen isotope inputs. While microwear complexity largely overlaps, both inter-individual dispersion and heterogeneity of complexity together with the anisotropy track dietary differences. The red deer is likely more engaged in grazing than the two bovids, which both plot as mixed feeders. When combined, dental microwear and carbon stable isotope analyses accurately reflect known ecological separation between the chamois and the roe deer. Both stable isotopes suggest niche separation by increasing enrichment from roe deer to red deer, to chamois; mouflons appear to feed as generalists. In roe deer, which shows the highest enamel oxygen isotope range (5.7 ‰), variation is nevertheless constrained compared to oxygen isotope ranges observed in regional precipitation, where the mean annual range reaches 9.9 ‰. However, through inverse modeling we estimate seasonal input ranges that average 9.7 ‰, a result strikingly similar to regional values. Altogether, our data demonstrate that given appropriate sampling strategies and modeling approaches, microwear and isotopic data can be effective tools for demonstrating niche separation among multiple sympatric herbivorous taxa.

Calcium isotopic variability of cervid bioapatite and implications for mammalian physiology and diet

“…Our isotopic data are thus compatible, at the first order, with the known diet variability of this cervid population, although this estimation of 0.09 ‰ is built upon coarse approximations (notably that consumed grass δ 44/42 Ca value was exactly -0.31 ‰ lower than non-grass food δ 44/42 Ca value) and need further investigations. A higher resolution regarding the post-weaning enamel record, and a better constrain of the Ca isotope composition of food items available at Bauges NRP (especially evergreen trees which are an important food source for these red deer, Redjadj et al (2014)) would provide δ 44/42 Ca data that will be more comparable with δ 13 C records, dental micro-wear and stomach content data collected so far for this red deer population (Redjadj et al, 2014;Merceron et al, 2021). Such further studies could notably help resolving some discrepancies between dental micro-wear and stomach content estimations (i.e.…”

About inter- and intra-specific variability of dental microwear texture in rodents: Study of two sympatric Proechimys (Echimyidae) species from the Cacao locality, French Guiana

“…Indeed, questions such as seasonality, or depositional timing are important issues in paleontology but also in archaeology (Milner and Bailey, 2005;Sánchez-Hernández et al 2014). Analysis of dental microwear and its intra-sample variation can complement other approaches to assess these aspects at a site scale (Kohn et al 1998;Berlioz et al 2017;Green et al 2018;Blumenthal et al 2019;Merceron et al 2021).…”

From leaves to seeds? The dietary shift in late Miocene colobine monkeys of southeastern Europe

“…The heterogeneity of texture complexity quantifies the variation of texture complexity observed within a scan (Hasfc) and is expected to be higher for animals with a versatile diet compared for instance to species with a specialized diet (Scott et al 2012;Ramdarshan et al 2016;Merceron et al 2018). The anisotropy of the microwear texture (epLsar) measures the orientation concentration of surface roughness, which is expected to be more directional (higher epLsar) for leaf eating species, notably when their diet includes tough foliages and silica-bearing plants (Scott et al 2012;Merceron et al 2021). Finally, the textural fill volume (Tfv) is the result of an algorithm that fills a surface with square cuboids of different volumes.…”

“…2012; Merceron et al. 2021). Finally, the textural fill volume (Tfv) is the result of an algorithm that fills a surface with square cuboids of different volumes.…”