Data from: Herbivorous dinosaur jaw disparity and its relationship to extrinsic evolutionary drivers

Morphological responses of nonmammalian herbivores to external ecological
drivers have not been quantified over extended timescales. Herbivorous
nonavian dinosaurs are an ideal group to test for such responses, because
they dominated terrestrial ecosystems for more than 155 Myr and included
the largest herbivores that ever existed. The radiation of dinosaurs was
punctuated by several ecologically important events, including extinctions
at the Triassic/Jurassic (Tr/J) and Jurassic/Cretaceous (J/K) boundaries,
the decline of cycadophytes, and the origin of angiosperms, all of which
may have had profound consequences for herbivore communities. Here we
present the first analysis of morphological and biomechanical disparity
for sauropodomorph and ornithischian dinosaurs in order to investigate
patterns of jaw shape and function through time. We find that
morphological and biomechanical mandibular disparity are decoupled:
mandibular shape disparity follows taxonomic diversity, with a steady
increase through the Mesozoic. By contrast, biomechanical disparity builds
to a peak in the Late Jurassic that corresponds to increased functional
variation among sauropods. The reduction in biomechanical disparity
following this peak coincides with the J/K extinction, the associated loss
of sauropod and stegosaur diversity, and the decline of cycadophytes. We
find no specific correspondence between biomechanical disparity and the
proliferation of angiosperms. Continual ecological and functional
replacement of pre-existing taxa accounts for disparity patterns through
much of the Cretaceous, with the exception of several unique groups, such
as psittacosaurids that are never replaced in their biomechanical or
morphological profiles.