Supplementary material from "Molecular clocks indicate turnover and diversification of modern coleoid cephalopods during the Mesozoic Marine Revolution"

Coleoid cephalopod molluscs comprise squids, cuttlefish and octopuses, and represent nearly the entire diversity of modern cephalopods. Sophisticated adaptations such as the use of colour for camouflage and communication (Mather 2008 Conscious. Cogn. 17, 37–48 (doi:10.1016/j.concog.2006.11.006 )), jet propulsion (Wells, O'Dor 1991 Bull. Mar. Sci. 49, 419–432) and the ink sac highlight the unique nature of the group. Despite these striking adaptations, there are clear parallels in ecology between coleoids and bony fishes (Packard 1972 Biol. Rev. Camb. Philos. Soc. 47, 241–307 (doi:10.1111/j.1469-185X.1972.tb00975.x); O'Dor, Webber 1986 Can. J. Zool. 64, 1591–1605 (doi:10.1139/z86-241)). The coleoid fossil record is limited, however, hindering confident analysis of the tempo and pattern of their evolution. Here we use a molecular dataset (180 genes, approx. 36 000 amino acids) of 26 cephalopod species to explore the phylogeny and timing of cephalopod evolution. We show that crown cephalopods diverged in the Silurian–Devonian, while crown coleoids had origins in the latest Palaeozoic. While the deep-sea vampire squids and dumbo octopuses have ancient origins extending to the Early Mesozoic Era, 242 ± 38 Ma, incirrate octopuses and the decabrachian coleoids (10-armed squid) diversified in the Jurassic Period. These divergence estimates highlight the modern diversity of coleoid cephalopods emerging in the Mesozoic Marine Revolution (Vermeij 1977 Paleobiology 3, 245–258 (doi:10.1017/S0094837300005352)), a period that also witnessed the radiation of most ray-finned fish groups (Near et al. 2012 Proc. Natl Acad. Sci. USA 109, 13 698–13 703 (doi:10.1073/pnas.1206625109)) in addition to several other marine vertebrates. This suggests that that the origin of modern cephalopod biodiversity was contingent on ecological competition with marine vertebrates.