Vol.:(0123456789) 1 3 Journal of Mammalian Evolution https://doi.org/10.1007/s10914-022-09645-1 ORIGINAL PAPER Suction causes novel tooth wear in marine mammals, with implications for feeding evolution in baleen whales Felix G. Marx 1,2  · David P. Hocking 3,4  · Travis Park 5  · Tahlia I. Pollock 4,7  · William M. G. Parker 4,6  · James P. Rule 4,5  · Erich M. G. Fitzgerald 4,6  · Alistair R. Evans 4,6 Accepted: 2 December 2022 © The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature 2023 Abstract Teeth are the primary tool used by most mammals to capture and process food. Over the lifetime of an individual, they pro- gressively wear through contact with each other (attrition) and with food (abrasion), creating distinctive patterns that refect function and diet. Unlike their terrestrial cousins, many marine mammals capture prey via suction, which so far has not been associated with a specifc wear pattern. Here, we describe two new types of tooth wear across 18 species of modern marine mammal (beaked whales, belugas, killer whales, globicephalines, and various seals) that likely stem from this behaviour: “glossowear”, which primarily afects the lingual side of the crown and plausibly records piston-like tongue movements dur- ing suction feeding; and “hydrowear”, which wraps around the sides of the crown and occurs as water is expelled from the mouth. Both wear types difer from attrition and biting-related abrasion in their surface characteristics and location on the crown. Horizontal scratches suggest a physical wear process, rather than dental erosion (acid corrosion) and tooth abfraction (microfracture). Since suction specifcally exploits the liquid properties of water, physical evidence of this behaviour may help to elucidate marine mammal feeding ecology and evolution. For example, glossowear is found in the toothed ancestors of baleen whales (mammalodontids, at least one aetiocetid, and likely Mystacodon), where it suggests an important role for suction in the emergence of flter feeding. By contrast, it is absent in most long-snouted toothed whales and dolphins, indicating that these animals mostly bite, rather than suck in, their prey. Keywords Abrasion · Cetacea · Mysticeti · Pinniped · Glossowear · Hydrowear Introduction Mammalian teeth are complex tools used for acquiring and pro- cessing food (Ungar 2010). Their elaborate shapes and occlusal relationships are unique among vertebrates, and often charac- teristic of particular feeding ecologies (Ungar 2015; Evans and Pineda-Munoz 2018). Most adult mammalian teeth are permanent, and therefore subject to a lifetime of physical and chemical assaults. The key mechanical stressors on a tooth are attrition, which is tooth-on-tooth wear, and abrasion, which is due to exogenous solids like food and grit that are forced onto the tooth during biting (Grippo et al. 2004). The resulting dam- age is characteristic of tooth function, diet, and habitat, and may afect – or even determine – feeding capabilities (Ungar 2015). Marine mammals like seals, whales, and dolphins are unu- sual in having simple teeth thought to function mainly in pierc- ing prey, which is then swallowed whole (Werth 2000b; Hocking et al. 2017b). In many living species, including numerous true seals (Marshall et al. 2008; Hocking et al. 2013; Marshall et al. 2014; Kienle et al. 2018; Kienle and Berta 2019), walruses Felix G. Marx and David P. Hocking are co-frst authors. * Felix G. Marx felix.marx@tepapa.govt.nz 1 Museum of New Zealand Te Papa Tongarewa, Wellington, New Zealand 2 Department of Geology, University of Otago, Dunedin, New Zealand 3 Tasmanian Museum and Art Gallery, Hobart, Australia 4 School of Biological Sciences, Monash University, Vic, Australia 5 Department of Life Sciences, Natural History Museum, London, UK 6 Museums Victoria, Melbourne, Vic, Australia 7 Department of Anatomy and Developmental Biology, Monash University, Vic, Australia