With more than 11,000 living species, birds are one of the most diverse groups of vertebrates on Earth. As the only surviving lineage of theropod dinosaurs, birds have fascinated both the public and scientists for decades. They offer valuable insight into evolution, revealing how anatomical transformations gave rise to the incredible diversity of species we see today. A new study led by a researcher at the Natural History Museum Bern (NMBE) sheds new light on the morphological evolution of birds.
Different evolutionary paths in modern birds
Modern birds are divided into two main groups: palaeognaths (such as ostriches and emus) and neognaths (nearly all other birds) and they differ notably in the morphology of the palate, the bones forming the roof of the mouth. For decades, palaeognaths were thought to retain a more dinosaur-like condition. But recent fossil discoveries challenge this view, suggesting that their palate may instead reflect more recent evolutionary changes rather than an ancient trait. Other researchers have also proposed that these differences might be explained by changes that arise during development. However, palate morphological change through development has remained largely unexplored.
For the first time, researchers from the NBME and Cambridge University have examined how palate morphology changes after hatching in 70 bird species, some of them coming from the NMBE collection, representing all major groups of living birds. By measuring and comparing how palate shape changes during bird growth, they demonstrate that palaeognaths and neognaths follow distinct developmental pathways from the earliest post-hatching stages to adulthood.
The role of developmental modes
Birds are well known for their great differences in developmental strategies. Some species are precocial, meaning their chicks hatch relatively mature, able to walk and move independently soon after emerging from the egg, as in ostriches. Others are altricial, with chicks that hatch vulnerable and remain in the nest for extended periods, relying on their parents for food and protection, as seen in many small songbirds. The team’s findings show that post-hatching development plays a key role in shaping an important functional part of the bird skull, which may have driven differences in evolutionary diversification across modern birds.
