Applying tribology to teeth of hoofed mammals

Abstract

Mammals inhabit all types of environments and have evolved chewing systems capable of processing a huge variety of structurally diverse food components. Surface textures of cheek teeth should thus reflect the mechanisms of wear as well as the functional traits involved. We employed surface textures parameters from ISO/DIS 25178 and scale-sensitive fractal analysis (SSFA) to quantify dental wear in herbivorous mammals at the level of an individual wear enamel facet. We evaluated cheek dentitions of two grazing ungulates: the Blue Wildebeest (Connochaetes taurinus) and the Grevy's Zebra (Equus grevyi). Both inhabit the east African grassland savanna habitat, but they belong to fundamentally different taxonomic units. We tested the hypothesis that the foregut fermenting wildebeest and the hindgut fermenting zebra show functional traits in their dentitions that relate to their specific mode of food-composition processing and digestion. In general, surface texture parameters from SSFA as well as ISO/DIS 25178 indicated that individual enamel ridges acting as crushing blades and individual wear facets of upper cheek teeth are significantly different in surface textures in the zebra when compared with the wildebeest. We interpreted the complexity and anisotropy signals to be clearly related to the brittle, dry grass component in the diet of the zebra, unlike the wildebeest, which ingests a more heterogeneous diet including fresh grass and herbs. Thus, SSFA and ISO parameters allow distinctions within the subtle dietary strategies that evolved in herbivorous ungulates with fundamentally different systematic affinities but which exploit a similar dietary niche.

The phylogenetic signal in tooth wear: What does it mean?

“…between certain distantly related taxa), but to document differences in diet when they might not necessarily be expected based on tooth morphology alone. Differences between closely related taxa have been captured, for instance, in bovids (Scott, 2012; Ungar, Merceron, & Scott, 2007), cervids (Berlioz, Kostopoulos, Blondel, & Merceron, 2017), ungulates (Schulz, Calandra, & Kaiser, 2010), feliforms (DeSantis & Haupt, 2014; DeSantis, Tseng, et al, 2017), canids (DeSantis et al, 2015), primates (Scott et al, 2005; Ungar, Grine, & Teaford, 2008), and macropodids (DeSantis, Field, Wroe, & Dodson, 2017; Prideaux et al, 2009). Indeed, many bioarchaeological studies have demonstrated distinctive and predictable diet‐related differences in both gross dental wear and microwear within a single species, Homo sapiens (Rose & Ungar, 1998).…”

Modular Wear Facet Nomenclature for mammalian post-canine dentitions

“…Butler himself (1978, p. 451) stated: 'Let those who are contemplating the introduction of new names pause to consider whether in so doing they are advancing the subject or making it more difficult to understand' . We aim for a broader comparative nomenclature that helps to describe facets for dental occlusion analysis (Kullmer et al 2009(Kullmer et al , 2012Fiorenza et al 2011;Benazzi et al 2013) and the analysis of masticatory biomechanics (Schulz & Kaiser 2010;Calandra et al 2012; offer the opportunity to characterize facets in more detail. Kaiser and Brinkmann (2006) introduced a labeling system of occlusal enamel ridge patterns in bovids and equids as a strictly function-orientated system that numbers facets (adopted from Janis 1990).…”

“…This system refers to the sequence of the antagonistic contact of facets, and in addition indicates the longitudinal position of the facet in relation to the cusp. Schulz and Kaiser (2010) applied the labeling system of Kaiser and Brinkmann (2006) to facets of upper and lower teeth that allow 3D surface texture measurements to infer oral behavior (e.g. diet reconstruction and chewing function) based on microscopic wear features.…”

“…diet reconstruction and chewing function) based on microscopic wear features. Schulz and Kaiser (2010) nomenclature will be used for, e.g. the phase of the chewing cycle (I for 'Phase I'; II for 'Phase II').…”

Application of Optical Topometry to Analysis of the Plant Epidermis

“…Applied to biological materials, the method is nondestructive and yields information-rich data sets containing both topography and reflective intensity for each coordinate in the field of view. OT has as yet seen limited application in biology, revealing details of wear on grazing ungulate teeth in one of the few published applications (Schulz et al, 2010). Here, we apply OT technology to the analysis of the cellular makeup of the plant epidermis and, in so doing, demonstrate its high-throughput, wide spatiotemporal resolution and stunning dimensionality.…”