Similar Associations of Tooth Microwear and Morphology Indicate Similar Diet across Marsupial and Placental Mammals

Abstract

Low-magnification microwear techniques have been used effectively to infer diets within many unrelated mammalian orders, but the extent to which patterns are comparable among such different groups, including long extinct mammal lineages, is unknown. Microwear patterns between ecologically equivalent placental and marsupial mammals are found to be statistically indistinguishable, indicating that microwear can be used to infer diet across the mammals. Microwear data were compared to body size and molar shearing crest length in order to develop a system to distinguish the diet of mammals. Insectivores and carnivores were difficult to distinguish from herbivores using microwear alone, but combining microwear data with body size estimates and tooth morphology provides robust dietary inferences. This approach is a powerful tool for dietary assessment of fossils from extinct lineages and from museum specimens of living species where field study would be difficult owing to the animal’s behavior, habitat, or conservation status.

Feeding ecology has a stronger evolutionary influence on functional morphology than on body mass in mammals

“…A prerequisite for using functional morphologies as ecological proxies, however, is the identification of ecomorphological traits that can be applied to higher level clades. Strong links between tooth morphology and diet have been previously established in mammals (Evans et al 2007;Boyer 2008;Christensen 2014;Pineda-Munoz et al 2017;Berthaume et al 2019), proving to be especially valuable for paleontological studies (Van Valkenburgh 1988;Janis 1995;Wilson et al 2012;Slater 2015;Grossnickle and Newham 2016;Chen et al 2019). The jaw correlates of diet presented in this study, especially JAPr distance and JAPr angle, may offer new functional traits that can be easily applied to broad studies of extant and fossil mammals.…”

“…For instance, extensive studies of mammalian dentitions have shown strong associations between mammalian tooth shape and diet, including convergent morphological evolution in distantly related taxa that occupy similar ecological niches (Evans et al. ; Boyer ; Christensen ; Pineda‐Munoz et al. ; Berthaume et al.…”

“…Further, investigations of jaw morphology and diet across Mammalia are rare, especially in comparison to similar studies of mammalian tooth shape (Evans et al. ; Boyer ; Christensen ; Pineda‐Munoz et al. ; Berthaume et al.…”

“…I examine mammalian jaw morphology because of its direct functional link to feeding ecology (Maynard Smith and Savage 1959;Turnbull 1970;Grossnickle and Polly 2013). Further, investigations of jaw morphology and diet across Mammalia are rare, especially in comparison to similar studies of mammalian tooth shape (Evans et al 2007;Boyer 2008;Christensen 2014;Pineda-Munoz et al 2017;Berthaume et al 2019). And a majority of studies on mammalian jaw shape and diet are qualitative (e.g., Maynard Smith and Savage 1959), lack statistical correction for phylogenetic non-independence (e.g., Grossnickle and Polly 2013), or focus on mammalian subclades rather than all of Mammalia (Radinsky 1981;Radinsky 1985;Anapol and Lee 1994;Janis 1995;Mendoza et al 2002;Nogueira et al 2005;Figueirido et al 2010;Meloro and O'Higgins 2011;Monteiro and Nogueira 2011;Ross et al 2012;Lazagabaster et al 2016;Maestri et al 2016;Arregoitia et al 2017).…”

A large carnivorous mammal from the Late Cretaceous and the North American origin of marsupials

“…It is quantified by counting pits and scratches on the enamel of the occlusal surface of the teeth and has been widely used to study the diet of a variety of mammals6970. These features reflect the material properties of the food and exogenous items eaten71.…”