Wear pattern of the molar dentition of an extant and an Oligocene bat assemblage with implications on functionality

Abstract

Wear stages have been defined based on dentine exposure at the lower molar surfaces for a population of the extant bat Pipistrellus pipistrellus (6 wear stages) and for a sample of the Oligocene bat Pseudorhinolophus antiquus (4 wear stages). Wear stages 1-2, which occur in juveniles, are characterised by punctual dentine exposure on the cusps and ridges. Wear stages 3-4, found in adult individuals, are characterised by connected areas of band-shaped dentine. The last two wear stages (5-6) reflect the dental condition of old (senile) individuals, with the molar surface showing wide areas of exposed dentine and the occlusal relief drastically reduced. The defined wear stages of the P. antiquus sample are comparable to stages 3-6 of P. pipistrellus. The molars of both species show wear facets with striations that go in two directions, indicating a two-phased, bucco-lingually directed masticatory movement which gains more freedom with progressive wear. This development underlines that shear-cutting dominates in the early stages of the mastication process, whereas in later stages a crushing component becomes increasingly dominant. Based on the average age determination of individuals from the defined wear stages, about 90 % of the studied P. pipistrellus population consists of juveniles (wear stages 1-2). In contrast, wear stages 3-5 (95 %) predominate in the studied sample of P. antiquus, indicating that most of the individuals were of an adult/senile age.

When the barn-owl feasted on bats, an approach to taphonomic analysis

“…In the first case (the only one where teeth-enamel dissolution has been observed), the higher enamel corrosion could be favoured by a more accused, age-related tooth-wear in this particular individual (Fig. 1): in Pipistrellus, wearfacets mainly develop on the lateral surfaces of the talonid and the trigonid (see a detailed study in Hielscher et al, 2015). On the other hand, several possible explanations for these high-level alteration degrees observed on a few specimens could yield on the biology of the barn-owl.…”

Assessing Age Related Cranial Characteristics and Morphometrics of the Egyptian Rousette (Rousettus aegyptiacus) from Central Africa

“…These bats belong to the families Hipposideridae — Hipposideros terasensis (Cheng and Lee, 2002) and Hipposideros cineraceus (Jin et al , 2010); Phyllostomidae — Phyllostomus hastatus (Stern and Kunz, 1998) and Artibeus watsoni (Chaverri and Kunz, 2006); Pteropodidae — Rousettus leschenaulti (Elangovan et al , 2002), Cynopterus sphinx (Elangovan et al , 2003), Pteropus poliocephalus (Divljan et al , 2006; Welbergen, 2010), Pteropus sp. (Giannini et al , 2006), and Eidolon helvum (Hayman et al , 2012 b ); Molossidae — Tadarida brasiliensis (Allen et al , 2010); Thyropteridae — Thyroptera tricolor (Chaverri and Vonhof, 2011); Vespertilionidae — Myotis lucifugus (Baptista et al , 2000), Eptesicus fuscus (Hood et al , 2002), Pipistrellus pipistrellus (Hielscher et al , 2015), Scotophilus kuhlii (Chen et al , 2016), Myotis emarginatus (Eghbali and Sharifi, 2018), and Chalinolobus gouldii (Eastick et al, 2022). All these studies assessed morphological and quantifiable characteristics which can be tracked ordinally throughout the lifespan of a bat using methods that examined dental degradation, body mass growth, sexual maturity, fusion of the epiphysis, cranial bone fusion, tooth development and skeletal growth (Baptista et al , 2000; Cheng and Lee, 2002; Divljan et al , 2006; Giannini et al , 2006; Brunet-Rossinni and Wilkinson, 2009; Hielscher et al , 2015).…”

“…(Giannini et al , 2006), and Eidolon helvum (Hayman et al , 2012 b ); Molossidae — Tadarida brasiliensis (Allen et al , 2010); Thyropteridae — Thyroptera tricolor (Chaverri and Vonhof, 2011); Vespertilionidae — Myotis lucifugus (Baptista et al , 2000), Eptesicus fuscus (Hood et al , 2002), Pipistrellus pipistrellus (Hielscher et al , 2015), Scotophilus kuhlii (Chen et al , 2016), Myotis emarginatus (Eghbali and Sharifi, 2018), and Chalinolobus gouldii (Eastick et al, 2022). All these studies assessed morphological and quantifiable characteristics which can be tracked ordinally throughout the lifespan of a bat using methods that examined dental degradation, body mass growth, sexual maturity, fusion of the epiphysis, cranial bone fusion, tooth development and skeletal growth (Baptista et al , 2000; Cheng and Lee, 2002; Divljan et al , 2006; Giannini et al , 2006; Brunet-Rossinni and Wilkinson, 2009; Hielscher et al , 2015). Except for Divljan et al (2006) and Hayman et al (2012 b ), these studies used rapid, non-destructive methods that do not harm live animals or damage preserved specimens which enabled examination of either infant bats of known age (Stern and Kunz, 1998; Baptista et al , 2000; Cheng and Lee, 2002; Elangovan et al , 2002, 2003; Chaverri and Kunz, 2006; Allen et al , 2010; Chaverri and Vonhof, 2011; Eghbali and Sharifi, 2018; Eastick et al , 2022) or preserved specimens of unknown age (Giannini et al , 2006; Hielscher et al , 2015).…”

“…All these studies assessed morphological and quantifiable characteristics which can be tracked ordinally throughout the lifespan of a bat using methods that examined dental degradation, body mass growth, sexual maturity, fusion of the epiphysis, cranial bone fusion, tooth development and skeletal growth (Baptista et al , 2000; Cheng and Lee, 2002; Divljan et al , 2006; Giannini et al , 2006; Brunet-Rossinni and Wilkinson, 2009; Hielscher et al , 2015). Except for Divljan et al (2006) and Hayman et al (2012 b ), these studies used rapid, non-destructive methods that do not harm live animals or damage preserved specimens which enabled examination of either infant bats of known age (Stern and Kunz, 1998; Baptista et al , 2000; Cheng and Lee, 2002; Elangovan et al , 2002, 2003; Chaverri and Kunz, 2006; Allen et al , 2010; Chaverri and Vonhof, 2011; Eghbali and Sharifi, 2018; Eastick et al , 2022) or preserved specimens of unknown age (Giannini et al , 2006; Hielscher et al , 2015).…”

Does age matter?—Efficiency of mechanical food break down in Tupaia belangeri at different ages

“…Wear facets occur along the steep flanks of cusps on the primary enamel coat. Progressing wear removes the enamel coat and levels the crown with increasingly age [ 15 , 26 , 27 ]. Thus, teeth of insectivorous mammals with a high crown relief (with pointed cusps) are possibly losing their effectivity through wear during progressing ontogeny.…”