Data from: Sustained miniaturization and anatomical innovation in the dinosaurian ancestors of birds

Recent discoveries have highlighted the dramatic evolutionary
transformation of massive, ground-dwelling theropod dinosaurs into light,
volant birds. Here, we apply Bayesian approaches (originally developed for
inferring geographic spread and rates of molecular evolution in viruses)
in a different context: to infer size changes and rates of anatomical
innovation (across up to 1549 skeletal characters) in fossils. These
approaches identify two drivers underlying the dinosaur-bird transition.
The theropod lineage directly ancestral to birds undergoes sustained
miniaturization across 50 million years and at least 12 consecutive
branches (internodes) and evolves skeletal adaptations four times faster
than other dinosaurs. The distinct, prolonged phase of miniaturization
along the bird stem would have facilitated the evolution of many novelties
associated with small body size, such as reorientation of body mass,
increased aerial ability, and paedomorphic skulls with reduced snouts but
enlarged eyes and brains.