Data from: Convergence and constraint in the cranial evolution of mosasaurid reptiles and early cetaceans

The repeated return of tetrapods to aquatic life provides some of the
best-known examples of convergent evolution. One comparison which has
received relatively little focus is that of mosasaurids (a group of Late
Cretaceous squamates) and archaic cetaceans (the ancestors of modern
whales and dolphins), both of which show high levels of craniodental
disparity, similar initial trends in locomotory evolution, and global
distributions. Here we investigate convergence in skull ecomorphology
during the initial aquatic radiations of these groups. A series of
functionally informative ratios were calculated from 38 species, with
ordination techniques used to reconstruct patterns of functional
ecomorphospace occupation. The earliest fully aquatic members of each
clade occupied different regions of ecomorphospace, with basilosaurids and
early russellosaurines exhibiting marked differences in cranial functional
morphology. Subsequent ecomorphological trajectories notably diverge:
mosasaurids radiated across ecomorphospace with no clear pattern and
numerous reversals, whereas cetaceans notably evolved towards shallower,
more elongated snouts, perhaps as an adaptation for capturing smaller
prey. Incomplete convergence between the two groups is present among
megapredatory and longirostrine forms, suggesting stronger selection on
cranial function in these two ecomorphologies. Our study highlights both
the similarities and divergences in craniodental evolutionary trajectories
between archaic cetaceans and mosasaurids, with convergences transcending
their deeply divergent phylogenetic affinities.