Wonky whales: the evolution of cranial asymmetry in cetaceans

Coombs, Ellen J.; Clavel, Julien; Park, Travis; Churchill, Morgan; Goswami, Anjali

doi:10.1186/s12915-020-00805-4

Table 2 List of the five landmarks with the greatest variation across the cranium for all cetaceans, archaeocetes, odontocetes, mysticetes, and terrestrial artiodactyls

From: Wonky whales: the evolution of cranial asymmetry in cetaceans

Suborder	Average asymmetry in the skull (x̄ρ)	1st highest landmark of variation		2nd highest landmark of variation		3rd highest landmark of variation		4th highest landmark of variation		5th highest landmark of variation		Specimen showing top 5 landmarks (red)
Suborder	Average asymmetry in the skull (x̄ρ)	Landmark description	x̄ρ_land	Landmark description	x̄ρ_land	Landmark description	x̄ρ_land	Landmark description	x̄ρ_land	Landmark description	x̄ρ_land	Specimen showing top 5 landmarks (red)
All cetaceans	0.268	L74: Dorsal medial maxilla (suture with nasal and premaxilla)	0.010	L68: Posterior lateral corner of nasal	0.009	L71: Posterior dorsal premaxilla	0.009	L121: Posterior point of nasal	0.008	L67: Left anterior lateral nasal	0.007
Archaeocetes	0.251	L72: Anterior lateral ventral premaxilla	0.007	L69: Tip of rostrum, anterior dorsal side, anterior midline of tooth row	0.007	L70: Anterior dorsal premaxilla	0.007	L82: Jugal posterior ventral	0.006	L73: Anterior lateral ventral maxilla	0.006
Odontocetes	0.290	L74: Dorsal medial maxilla (suture with nasal and premaxilla)	0.013	L68: Posterior lateral corner of nasal	0.011	L71: Posterior dorsal premaxilla	0.010	L121: Posterior point of nasal	0.009	L67: Left anterior lateral nasal	0.009
Mysticetes	0.191	L78: Posterior ventral lateral most point of maxilla (near orbit)	0.005	L79: Posterior tooth row lateral maxilla	0.005	L72: Anterior lateral ventral premaxilla	0.005	L71: Posterior dorsal premaxilla	0.005	L122: Anterior medial frontal	0.005
Terrestrial artiodactyls	0.171	L83: Lateral posterior frontal (posterior lateral parietal suture)	0.006	L87: Anterior medial parietal	0.005	L97: Posterior lateral most point of the mandibular articular process	0.005	L80: Jugal anterior dorsal	0.005	L98: Lateral posterior squamosal (occipital suture)	0.004

ρ is the radius value calculated as the Euclidean distance between the computer-mirrored landmark and the manually placed landmark. The larger the value for ρ, the more it is displaced, indicating asymmetry between the two sides of the cranium. x̄ρ is the average of the total radii (∑ρ) values across the skull for all the specimens in that group. x̄ρ_land is the average radii across all specimens in that group for that landmark. Each image shows the position of the five landmarks of greatest variation for each respective group. Skulls not to scale

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ISSN: 1741-7007

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