Neuroanatomy of South American Coraciimorphae: morphological differences of the endocranium of Piciformes and Galbuliformes

DEMMEL FERREIRA, M. M; DEGRANGE, F. J.; TIRAO, G. A.; TAMBUSSI, C. P.

Congreso; XVlll Reunión Argentina de Ornitología; 2019

Although endocranial morphology varies across Aves, variation among related taxa still remains largely unknown. There is no consensus on the relationship between Galbulidae, Bucconidae, Picidae and Ramphastidae, since they were all first included in the order Piciformes but now are separated into Galbuliformes (Galbulidae and Bucconidae) and Piciformes (Picidae and Ramphastidae). The aim of this work is to explore the endocranial morphology of Neotropical Coracimorphae, in an attempt to elucidate morphological differences that will benefit future phylogenetic analyses. Eleven skulls of adult Piciformes and Galbuliformes were CT scanned and 3D endocast models of the brain were generated. Regression analysis show that only Galbulidae have a smaller brain than expected for a bird of its body mass. All specimens have an airencephalic type of brain, laterally expanded telencephalic hemispheres (less marked in Picidae), small olfactory bulbs and elongated cerebellum with marked folia. Galbuliformes show long although poorly dorsally developed wulsts, contrasting with Piciformes which have very developed wulsts. The orientation of the hypophysis (regarding the horizontal semi-circular canal of the inner ear) in Galbuliformes is variable among taxa, while in Piciformes has a vertical disposition. Galbuliformes show large optic lobes, displaced rostrally in Bucconidae but caudally in Galbulidae. In Picidae, the optic lobes are partially overlapped by ventrolateral projections of the telencephalic hemispheres, whereas in Ramphastidae they are rostrally displaced and are kidney-shaped. The contact between cerebellum and telencephalon has a slightly ?V? shape in Galbulidae and Picidae, whereas is more straightened in Bucconidae and Ramphastidae. Flocculi are small and poor projected laterally in Bucconidae and Picidae, but are more robust in Galbulidae and Ramphastidae, where they are observable from dorsal view. The morphological differences found provide key information that can be applied in phylogenetic studies that could potentially reveal the evolution of the Coracimorphae.