Data from: Frog limbs in deep time: is jumping locomotion at the roots of the anuran Bauplan?

The unique body plan of frogs (Lissamphibia: Anura) has been largely
conserved from at least 200 Myr and its evolution from a more generalized
tetrapod condition is still poorly understood, in part due to the scarce
early fossil record of Salientia, the anuran total-group. The origin of
the anuran Bauplan has been classically explained as an adaptation to
jumping, but recent studies incorporating new data in a phylogenetic
context have challenged the popular jumping hypothesis. Here we revisit
and test this hypothesis from a palaeobiological perspective by
integrating limb data from a wide range of extant and fossil frogs. We
first explored the evolution of limb proportions from the Jurassic to the
Paleogene to understand when the present limb diversity originated and
whether, and to what extent, limb proportions have been conserved over the
last 200 Myr. We then inferred the locomotor capabilities of extinct
species by phylogenetic flexible discriminant analysis and, from these
inferences, we studied the locomotor diversity of frogs over geological
time and reconstructed the ancestral state for frog-like salientians. The
evolution of limb proportions is characterized by an early diversification
that was underway in the Jurassic, followed by a repeated convergence over
a limited area of the morphospace that was already explored by the Early
Cretaceous. In agreement with this early limb diversity, the Jurassic stem
species were also locomotory diverse and their inferred locomotor modes do
not support the jumping hypothesis. We propose that the patterns found
herein of repeated convergent evolution of both limb proportions and
locomotor capabilities over geological time hamper any attempt to
confidently infer the ancestral locomotion mode and, therefore, it might
be time to start focusing on other hypotheses on the origin of the anuran
Bauplan that are not related to locomotion.