Ontogenetic allometry underlies trophic diversity in sea turtles (Chelonioidea)

Abstract Despite only comprising seven species, extant sea turtles (Cheloniidae and Dermochelyidae) display great ecological diversity, with most species inhabiting a unique dietary niche as adults. This adult diversity is remarkable given that all share the same juveniles. These ontogenetic shifts in diet, well dramatic increase body size, make an excellent group to examine how morphological arises by allometric processes life habit specialisation. Using three-dimensional geometric morphometrics, we characterise allometry skulls of evaluate variation context phylogenetic history diet. Among sample, olive ridley ( Lepidochelys olivacea ) has seemingly average turtle skull shape generalised whereas green Chelonia mydas hawksbill Eretmochelys imbricata show different extremes snout associated their modes food gathering (grazing vs. grasping, respectively). Our findings corroborate previous suggestions leatherback Dermochelys coriacea paedomorphic, having similar proportions hatchlings other retaining hatchling-like diet relatively soft bodied organisms. The flatback Natator depressus shows but less extreme pattern. By contrast, loggerhead Caretta caretta peramorphic signal increased jaw muscle volumes allow predation on hard shelled prey. Kemp’s kempii compared its sister ridley, includes harder prey items such crabs. We suggest may be significant factor driving differences among species. Although small number limits statistical power, shape, are consistent hypothesis trajectory facilitated diversification observed increasing vertebrate groups.