Another reason for their size is associated with their rapid metamorphosis, which seems to have evolved only in the ancestors of lissamphibia; in all other known lines the development was much more gradual.
ɐnˈʌðɚ ɹˈiːzən fɔːɹ ðɛɹ sˈaɪz ɪz ɐsˈoʊsɪˌeɪɾᵻd wɪð ðɛɹ ɹˈæpɪd mˌɛɾəmˈoːɹfəsˌɪs, wˌɪtʃ sˈiːmz tə hæv ɪvˈɑːlvd ˈoʊnli ɪnðɪ ˈænsɛstɚz ʌv lˌɪsɐmfˈɪbiə; ɪn ˈɔːl ˈʌðɚ nˈoʊn lˈaɪnz ðə dɪvˈɛləpmənt wʌz mˈʌtʃ mˈoːɹ ɡɹˈædʒuːəl.