The imagery on this page is the basis for a paper entitled Massive, Solidified Bone in the Wing of a Volant Courting Bird, by K.S. Bostwick, M.L. Riccio and J.M. Humphries (2012, Biology Letters, 8, 760-763). The abstract is as follows:
One pervasive morphological feature of tetrapods is the pipe-like, often marrow-filled, structure of the limb or long bones. This ‘hollow’ form maximizes flexural strength and stiffness with the minimum amount of bony material, and is exemplified by truly hollow (air-filled), or pneumatic, humeri in many modern birds. High-resolution microCT scans of the wings of two male club-winged manakins (Machaeropterus deliciosus) uncovered a notable exception to the hollow-tube rule in terrestrial vertebrates; males exhibited solidified ulnae more than three times the volume of birds of comparable body size, with significantly higher tissue mineral densities. The humeri exhibited similar (but less extreme) modifications. Each of the observed osteological modifications increases the overall mass of the bone, running counter to pervasive weight-reducing optimizations for flight in birds. The club-winged manakin is named for a pair of unique wing feathers found in adult males; these enlarged feathers attach directly to the ulna and resonate to produce a distinctive sound used in courtship displays. Given that the observed modifications probably assist in sound production, the club-winged manakin represents a case in which sexual selection by female choice has generated an ecologically ‘costly’ forelimb morphology, unique in being specialized for sound production at a presumed cost in flight efficiency.
About the Species
This whole specimen was collected from Bocas del Toro, Panama by J.T. Weir on 9 March 2003. It was made available to The University of Texas High-Resolution X-ray CT Facility for scanning by Dr. Kim Bostwick of Cornell University and Dr. Timothy Rowe of the Department of Geological Sciences, The University of Texas at Austin. Funding for scanning was provided by a National Science Foundation Digital Libraries Initiative grant to Dr. Rowe.
About this Specimen
This specimen was scanned by Matthew Colbert on 7 July 2004 along the coronal axis for a total of 415 slices. Each 1024x1024 pixel slice is 0.0576 mm thick, with an interslice spacing of 0.0576 mm and a field of reconstruction of 26 mm.
YouTube video showing Dr. Bostwick demonstrating the interesting moonwalk of the red-capped manakin