Hoatzin nestling locomotion: Acquisition of quadrupedal limb coordination in birds Affiliations

Anick Abourachid (1) , Anthony Herrel (1) , Thierry Décamps (1) , Fanny Pages (1) , Anne-Claire Fabre (1) , Luc Van Hoorebeke , Dominique Adriaens (2) , Maria Alexandra Garcia Amado

1 MECADEV - Mécanismes Adaptatifs et Evolution
2 UGENT - Universiteit Gent = Ghent University

The evolution of flight in birds involves 1) a decoupling of the primitive quadrupedal locomotor coordination, with a new synchronized flapping motion of the wings while conserving alternating leg movements and 2) the reduction of the wing digits and the loss of functional claws. Our observations show that the hoatzin nestlings move with an alternated walking coordination of the four limbs using the mobile claws on their wings to anchor themselves to the substrate. When swimming, hoatzin nestlings use a coordinated motion of the four limbs involving synchronous or alternated movements of the wings, indicating a versatile motor pattern. Finally the proportions of the claws and phalanges in juvenile hoatzin are radically divergent from those in adults, yet strikingly similar to those of Archaeopteryx. The locomotor plasticity observed in the Hoatzin suggests that transitional forms that retained claws on the wings could have also use them for locomotion.

Domains: Life Sciences [q-bio]; Animal biology

Anick Abourachid, Anthony Herrel, Thierry Décamps, Fanny Pages, Anne-Claire Fabre, et al.. Hoatzin nestling locomotion: Acquisition of quadrupedal limb coordination in birds Affiliations. Science Advances , 2019, 22, ⟨10.1126/sciadv.aat0787⟩. ⟨mnhn-02496736⟩