Biological Evolution; Neuropeptides/metabolism; Parathyroid Glands/embryology; Parathyroid Glands/metabolism; Trans-Activators/metabolism; Amino Acid Sequence; Animals; Chick Embryo; DNA-Binding Proteins; Dogfish/embryology; Dogfish/genetics; Dogfish/metabolism; Gills/embryology; Gills/metabolism; Gnathostoma/embryology; Gnathostoma/genetics; Gnathostoma/metabolism; Humans; Molecular Sequence Data; Neuropeptides/genetics; Organ Specificity; Parathyroid Hormone/chemistry; Parathyroid Hormone/genetics; Pharynx/embryology; Pharynx/metabolism; Phylogeny; Sequence Alignment; Trans-Activators/genetics; Transcription Factors; Zebrafish/embryology; Zebrafish/genetics; Zebrafish/metabolism; Zebrafish Proteins