Research on birds indicates that the occurrence of beak keratin and teeth are mutually
exclusive, and both traits are widely distributed across Dinosauria. The macroevolution of …

Teeth evolved early in vertebrate evolution, and their morphology reflects important
specializations in diet and ecology among species. The toothless jaws (edentulism) in extant …

We are seldom able to directly observe evidence of soft tissue morphology or feeding
behavior of extinct species; thus, reconstructing their ecologies is notoriously difficult, and …

The keratinous beak is inferred to have evolved multiple times in the Archosauria and in
Aves. Unfortunately, this feature rarely preserves in the fossil record. Here we examine a …

Beaks are innovative structures characterizing numerous tetrapod lineages, including birds,
but little is known about how developmental processes influenced the macroevolution of …

Primates have a most idiosyncratic cranial form when compared with other terrestrial
mammals. Yet, primate cranial form is also widely variable among primate groups, while …

Recent discoveries of exquisitely preserved nonavialan and avialan theropod dinosaurs
have not only prompted studies of theropod tooth morphologies, but have also provided …

The research presented here is an examination of the morphology and histology of several
broad categories of skin structures in living amniotes, together with analyses of the …

Feathers of today's birds are constructed of beta (β)‐keratins, structural proteins of the
epidermis that are found solely in reptiles and birds. Discoveries of “feathered dinosaurs” …

Over the last two decades, the dinosaur fossil record has revealed much about the nature of
their epidermal structures. These data challenged long-standing hypotheses of widespread …