ðə pˈɛktɚɹəl fˈɪnz wɜː ɪnstˈɛd ɹᵻplˈeɪst baɪ bˈoʊni spˈaɪnz, pˈɑːsᵻbli fɔːɹ pɹətˈɛkʃən ɐɡˈɛnst pɹˈɛdəɾɚz, ænd ðɛɹwˌʌz ɐ ɹˈoʊ ʌv spˈaɪnz ɐlˈɔŋ ðə bˈæk.
The pectoral fins were instead replaced by bony spines, possibly for protection against predators, and there was a row of spines along the back.