Late Cretaceous bird from Madagascar reveals unique development of beaks

• Published in: Nature (London) Vol. 588; no. 7837; pp. 272 - 276
• Main Authors: O’Connor, Patrick M., Turner, Alan H., Groenke, Joseph R., Felice, Ryan N., Rogers, Raymond R., Krause, David W., Rahantarisoa, Lydia J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10-12-2020; Nature Publishing Group
• Subjects: 631/181/414; 704/181; Adaptation; Animals; Beak; Beak - anatomy & histology; Beaks; Biological Evolution; Birds; Birds - anatomy & histology; Birds - classification; Cretaceous; Ecology; Edentulous; Enlargement; Extinct birds; Feeding behavior; Fossils; Humanities and Social Sciences; Lability; Madagascar; Maxilla; Mesozoic; Morphology; multidisciplinary; Natural history; New species; Pattern formation; Phenotypes; Phylogenetics; Phylogeny; Physiological aspects; Rostrum; Science; Science (multidisciplinary); Stems; Madagascar
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-020-2945-x

Mesozoic birds display considerable diversity in size, flight adaptations and feather organization
1
–
4
, but exhibit relatively conserved patterns of beak shape and development
5
–
7
. Although Neornithine (that is, crown group) birds also exhibit constraint on facial development
8
,
9
, they have comparatively diverse beak morphologies associated with a range of feeding and behavioural ecologies, in contrast to Mesozoic birds. Here we describe a crow-sized stem bird,
Falcatakely forsterae
gen. et sp. nov., from the Late Cretaceous epoch of Madagascar that possesses a long and deep rostrum, an expression of beak morphology that was previously unknown among Mesozoic birds and is 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.
A crow-sized stem bird,
Falcatakely forsterae
, possesses a long and deep rostrum—a beak morphology that was previously unknown among Mesozoic birds and is similar to that of some crown-group birds, such as toucans.