Late Cretaceous bird from Madagascar reveals unique development of beaks Project ID: 00000C894 Public

25 Media · 1 Specimen · Managed by: Patrick OConnor, Joseph Groenke

Mesozoic birds display considerable diversity in size, flight adaptations and feather organization, but exhibit relatively conserved patterns of beak shape and development. Although crown group birds also exhibit constraint on facial development, they have comparatively diverse beak morphologies associated with a range of feeding and behavioural ecologies, in contrast to Mesozoic birds. Falcatakely forsterae from the Late Cretaceous epoch of Madagascar possesses a long and deep rostrum, an expression of beak morphology previously unknown among Mesozoic birds and superficially similar to that of a variety of crown-group birds (for example, toucans). The rostrum of Falcatakely is composed of an expansive edentulous maxilla and a small tooth-bearing premaxilla. Morphometric analyses of individual bony elements and three-dimensional rostrum shape reveal the development of a neornithine-like facial anatomy despite the retention of a maxilla–premaxilla organization that is similar to that of nonavialan theropods. The patterning and increased height of the rostrum in Falcatakely reveals a degree of developmental lability and increased morphological disparity that was previously unknown in early branching avialans. Expression of this phenotype (and presumed ecology) in a stem bird underscores that consolidation to the neornithine-like, premaxilla-dominated rostrum was not an evolutionary prerequisite for beak enlargement.