Incisor tooth wear and age determination in mountain gorillas from Volcanoes National Park, Rwanda

Abstract

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Robust age estimation of southern sea otters from multiple morphometrics

“…Among all features related to external morphology, the single best predictor of age after juvenile stage (≥1 year) was tooth attrition, which is consistent with other minimally invasive aging studies using known-age individuals (Chevallier et al, 2017;Delahay et al, 2011;Galbany et al, 2018;Gipson et al, 2000;Stander, 1997). Wild sea otters are primarily susceptible to dental attrition from foraging on hard-shelled invertebrates (Fisher, 1941;Kenyon, 1969;Winer, Liong, & Verstraete, 2013), many which burrow in sand.…”

“…For each age estimate, we also defined an aging error, ranging from <1 day (for a known birth event) to 3 years (for individuals first examined as aged adults). A (±) 3‐year maximum error is consistent with other studies quantifying the precision of aging carnivores from tooth wear only (Chevallier et al., 2017; Galbany et al., 2018; Gipson et al., 2000).…”

“…where L(t) is the predicted length at age t, L oo is the population mean asymptotic length, k is a growth parameter of dimension time −1 , and t 0 is the age at length = 0, or (-) gestation. The VBGF is a robust tool for modeling age to size relationships (i.e., mass, length, and girth) across multiple taxa of marine vertebrates (Estess et al, 2014;Garde, Heide-Jørgensen, Hansen, Nachman, & Forchhammer, 2007;Nielsen et al, 2016;Van Houtan, Andrews, Jones, Murakawa, & Hagemann, 2016), including sea otters (Laidre et al, 2006;Palomares & Pauly, 2008;Tinker et al, 2013Tinker et al, , 2017 3-year maximum error is consistent with other studies quantifying the precision of aging carnivores from tooth wear only (Chevallier et al, 2017;Galbany et al, 2018;Gipson et al, 2000).…”

Skeletal ageing in Virunga mountain gorillas

“…In three cases, uncertainty in birth date (and thus age) ranged between ±1.5 and ±4 years (see electronic supplementary material, table S1 for details). Ages for 10 other individuals were estimated from incisor tooth wear using population-specific formulae developed for the MGSP sample [33] and for one individual from dental developmental maturity [34]. One additional individual was included in lumbar vertebral but not long bone analyses; its age was estimated from tooth wear [33].…”

“…Ages for 10 other individuals were estimated from incisor tooth wear using population-specific formulae developed for the MGSP sample [33] and for one individual from dental developmental maturity [34]. One additional individual was included in lumbar vertebral but not long bone analyses; its age was estimated from tooth wear [33]. Age distributions by sex are shown in figure 1.…”