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Abstract:
The use of differing definitions of homology has led to controversies about the identity of bony elements in vertebrate skulls. An example is the controversy concerning the identity of the avian frontal, which has been assigned that name based on its location and shape. However, developmentally, it has been suggested to be a fusion of the frontal and parietal (i.e. frontoparietal). To assist in resolving this controversy, a search for a suture in the gap between the two ossification centres of the chicken's frontal was attempted. The production of a staging table of the chicken skull revealed a putative suture would be found between stages HH36 and 37. Histological examination of the developing frontal failed to find any evidence of a frontal-parietal suture, leading to the conclusion that the avian frontal is a single element formed from two ossification centers and is not a frontoparietal.