The defining characteristic of a vertebrate is the vertebral column, formed in the development of the segmented series of vertebrae.
ðə dᵻfˈaɪnɪŋ kˌæɹɪktɚɹˈɪstɪk əvə vˈɜːɾɪbɹˌeɪt ɪz ðə vˈɜːɾɪbɹəl kˈɑːlʌm, fˈɔːɹmd ɪnðə dɪvˈɛləpmənt ʌvðə sɛɡmˈɛntɪd sˈɪɹiz ʌv vˈɜːɾɪbɹˌiː.