Data from: Decoupled diversification dynamics of feeding morphology following a major functional innovation in marine butterflyfishes

The diversity of fishes on coral reefs is influenced by the evolution of feeding innovations. For instance, the evolution of an intramandibular jaw joint has aided shifts to corallivory in Chaetodon butterflyfishes following their Miocene colonization of coral reefs. Today, over half of all Chaetodon species consume coral, by far the largest concentration of corallivores in any reef fish family. In contrast to Chaetodon, other chaetodontids remain less intimately associated with coral and mainly consume other invertebrate prey. Here, we test (i) if intramandibular joint evolution in Chaetodon accelerated diversification of feeding morphology, and (ii) if cranial and post-cranial traits were affected similarly. We measured 19 cranial functional morphological traits, gut length and body elongation for 33 Indo-Pacific species. Comparisons of Brownian motion rate parameters revealed that cranial diversification was about four times slower in Chaetodon butterflyfishes with the intramandibular joint, as compared to other chaetodontids. However, rate of gut length evolution was significantly faster in Chaetodon, with no group-differences for body elongation. The contrasting patterns of cranial and postcranial morphological evolution stress the importance of comprehensive datasets in ecomorphology. The intramandibular joint appears to enhance coral feeding ability in Chaetodon and represents a design break-through that facilitates this trophic strategy. Meanwhile, variations in gut anatomy may reflect diversity in how coral tissues are procured and assimilated. Bannerfishes, by contrast retain a relatively unspecialized gut for processing invertebrate prey, but have evolved some of the most extreme cranial mechanical innovations among bony fishes for procuring elusive prey.