Ecomorphology of toothed whales (Cetacea, Odontoceti) as revealed by 3D skull geometry

Abstract

Extant odontocetes (toothed whales) exhibit differences in body size and brain mass, biosonar mode, feeding strategies, and diving and habitat adaptations. Strong selective pressures associated with these factors have likely contributed to the morphological diversification of their skull. Here, we used 3D landmark geometric morphometric data from the skulls of 60 out of ~ 72 extant odontocete species and a well-supported phylogenetic tree to test whether size and shape variation are associated with ecological adaptations at an interspecific scale. Odontocete skull morphology exhibited a significant phylogenetic signal, with skull size showing stronger signal than shape. After accounting for phylogeny, significant associations were detected between skull size and biosonar mode, body length, brain and body mass, maximum and minimum prey size, and maximum peak frequency. Brain mass was also strongly correlated with skull shape together with surface temperature and average and minimum prey size. When asymmetric and symmetric components of shape were analysed separately, a significant correlation was detected between sea surface temperature and both symmetric and asymmetric components of skull shape, and between diving ecology and the asymmetric component. Skull shape variation of odontocetes was strongly influenced by evolutionary allometry but most of the associations with ecological variables were not supported after phylogenetic correction. This suggests that ecomorphological feeding adaptations vary more between, rather than within, odontocete families, and functional anatomical patterns across odontocete clades are canalised by size constraints.

Skull morphology of bottlenose dolphins worldwide and patterns of adaptation between coastal and offshore environments

“…A Procrustes fit was carried out to standardize the effects of size, orientation and positioning, with skulls aligned to their principal axis. Odontocete skulls are often asymmetric (Laeta et al., 2021), and previous studies have shown that the patterns of asymmetry can be complex (Galatius & Goodall, 2016) and show distinct variation patterns relative to symmetrical shape component (Vicari et al., 2023). Therefore, the asymmetrical component was separated from the symmetrical component for both dorsal and ventral analyses using the function ‘bilat.symmetry’ to average both sides of the skull across the midline.…”

An Enhanced Methodology for Creating Digital Twins within a Paleontological Museum Using Photogrammetry and Laser Scanning Techniques

“…Numerous projects and applications have emerged, showcasing the effectiveness of photogrammetry and laser scanning in the realm of natural history digitization [11][12][13][14][15][16][17][18][19][20][21][22]. These initiatives have demonstrated the extensive array of possibilities and advancements within this field.…”

“…For example, an exemplary project [13] demonstrates the feasibility of using structured light scanners to capture field data and create high-resolution, interactive 3D models of at-risk natural history resources. Additionally, in a study involving toothed whales [21], 3D landmark geometric morphometric data were used from the skulls of 60 out of 72 extant odontocete species and a well-supported phylogenetic tree to test whether size and shape variation are associated with ecological adaptations at an interspecific scale.…”