Data from: Crocodylomorph cranial shape evolution and its relationship with body size and ecology

Crocodylomorpha, which includes living crocodylians and their extinct
relatives, has a rich fossil record, extending back for more than 200
million years. Unlike modern semi-aquatic crocodylians, extinct
crocodylomorphs exhibited more varied lifestyles, ranging from marine to
fully terrestrial forms. This ecological diversity was mirrored by a
remarkable morphological disparity, particularly in terms of cranial
morphology, which seems to be closely associated with ecological roles in
the group. Here, I use geometric morphometrics to comprehensively
investigate cranial shape variation and disparity in Crocodylomorpha. I
quantitatively assess the relationship between cranial shape and ecology
(i.e. terrestrial, aquatic, and semi-aquatic lifestyles), as well as
possible allometric shape changes. I also characterise patterns of cranial
shape evolution and identify regime shifts. I found a strong link between
shape and size, and a significant influence of ecology on the observed
shape variation. Terrestrial taxa, particularly notosuchians, have
significantly higher disparity, and shifts to more longirostrine regimes
are associated with large-bodied aquatic or semi-aquatic species. This
demonstrates an intricate relationship between cranial shape, body size
and lifestyle in crocodylomorph evolutionary history. Additionally,
disparity-through-time analyses were highly sensitive to different
phylogenetic hypotheses, suggesting the description of overall patterns
among distinct trees. For crocodylomorphs, most results agree in an early
peak during the Early Jurassic and another in the middle of the
Cretaceous, followed by nearly continuous decline until today. Since only
crown-group members survived through the Cenozoic, this decrease in
disparity was likely the result of habitat loss, which narrowed down the
range of crocodylomorph lifestyles.