Dental macro- and microwear in Carinodens belgicus, a small mosasaur from the type Maastrichtian

Abstract

Teeth of the small durophagous mosasaur Carinodens belgicus are known from Maastrichtian Atlantic-Tethyan deposits worldwide. The peculiar dentition of Carinodens inspired debate and speculation on its dietary niche ever since its first description. In this contribution, we describe the macro- and microwear pattern in five well-preserved isolated teeth, allowing further and independent evaluation of aspects of feeding behaviour and diet. Macroscopically, wear is concentrated on the apex and mesiodistal sides. Microwear was mapped using Scanning Electron Microscopy at several magnifications and can be characterised as scratches and pits. Coarse scratches were found to be the most common and pits were found to be the least common feature. Scratch orientation is primarily along the mesiodistal plane or in the labiolingual plane with an angle of ~130°. These microwear features can be explained either by oral processing or passive abrasion by sediments or food. As scratch width only indicates the minimum width of the abrading particle, the material causing the wear here could have ranged from silica-based silts to larger abrasives. However, in this case, abrasion by sediments might not explain this wear because of the biocalcarenitic nature of the type Maastrichtian sediments; siliciclastics are virtually absent. Therefore it is more likely that hard food particles, such as benthic organisms with hard exoskeletons, caused the wear on the enamel of Carinodens, or Carinodens ventured out to more sandy areas to forage as well. The mesiodistal and labiolingual direction of the microwear scratches might suggest that Carinodens showed more complexity in the use of its teeth than simple grasping, and that a gripping and pulling motion during feeding similar to that employed by modern varanids may have been the cause.

Xenodens calminechari gen. et sp. nov., a bizarre mosasaurid (Mosasauridae, Squamata) with shark-like cutting teeth from the upper Maastrichtian of Morocco, North Africa

“…Stable isotopes confirm that these diverse tooth structures reflect diverse diets (Polcyn et al, 2013;. Tooth wear similarly implies diverse feeding strategies (Holwerda et al, 2013).…”

“…The new mosasaurid exhibits a dental battery with numerous small, short, bladelike teeth packed together to form a saw-like cutting edge. Features of the jaws and teeth suggest affinities with the mosasaurid Carinodens, a taxon with crushing teeth (Bardet et al, 2008;Schulp et al, 2009;Holwerda et al, 2013;Mulder et al, 2013;Milàn et al, 2018).…”

Masticatory mechanisms, dental function, and diet in Triassic trilophosaurids (Reptilia: Allokotosauria)

“…Graph of pit-to-scratch ratios. Black points indicate mean ratios across taxa, gray points indicate singular taxon ratios (from Pinto Llona (2006) [ o , p ]; Holwerda et al (2013) [ n ]; Kubo & Kubo (2014) [ c – m , q – t ], yellow points indicate ratios of specimens from this study, vertical black lines indicate the range of values across taxa, horizontal orange lines indicate the value of the point they pass through, and the gray horizontal box indicates the range of values found for Trilophosaurus buettneri and Trilophosaurus phasmalophos . a: mean pit-to-scratch ratios for Trilophosaurus buettneri with both teeth, distal tooth, and distal side of distal tooth in descending value; b: mean ratios for Trilophosaurus phasmalophos with PEFO 42082 and DMNH PAL 2018-05-0012 in descending value; c: mean ratio for the unnamed taxon (PEFO 43837); d: data for grazers; e: data for mixed feeders; f: data for browsers; g: data for folivores (i.e.…”

“…Though its use in living and extinct mammals (especially primates) is well established, its application to living and extinct reptiles is burgeoning ( Ungar 2015; Bestwick et al 2019; Winkler et al 2019). Dental microwear analysis in living lizards (e.g., Winkler et al 2019), living and extinct crocodylians (e.g., Ősi & Weishampel 2009; Young et al 2012; Bestwick et al 2019), extinct lepidosaurs (e.g., Holwerda et al 2013; Gere et al 2021), and extinct archosauromorphs ( Fiorillo 1998; Williams & al. 2009; Ősi & Weishampel 2011; Mallon & Anderson 2014; Ősi & Weishampel et al 2014; Varriale 2016; Rivera-Sylva et al 2019; Kubo et al 2021) found that microwear patterns are linked to dietary preference and jaw movement in reptiles just as they are in mammals.…”

Controlled feeding experiments with juvenile alligators reveal microscopic dental wear texture patterns associated with hard-object feeding

“…Because diet proxies based on tooth-wear patterns can enable inferences of niche partitioning among sympatric species (Fiorillo, 1998;Mallon and Anderson, 2014), they can enhance reconstructions of paleoecosystems. Several studies have linked microscopic (2D microwear) and macroscopic tooth wear to paleodiet in extinct archosauriforms (Schubert and Ungar, 2005;Williams et al, 2009;Varriale, 2016;Virag and Osi, 2017) and squamates (Holwerda et al, 2013;Gere et al, 2021). Therefore, comparisons of DMT observed in extant reptiles could also be helpful for the reconstruction of the paleoecology of taxa such as dinosaurs, with extant toothed archosaurs (crocodylians) likely being the best candidates to study as a model for theropod dental wear.…”