ðɪ ˈoʊldɪst nˈoʊn dˌɪnəsˈɔːɹəmˌoːɹf ɪz ɐsˌɪlɪsˈɔːɹəs, ɐ saɪlsˈɔːɹɪd wˌɪtʃ mˌeɪhɐv lˈɪvd æz ˈɜːli æz ðɪ ænˈɪʒən ˈeɪdʒ ʌvðə mˈɪdəl tɹaɪˈæsɪk pˈiəɹɪəd, ɐbˌaʊt tˈuːhˈʌndɹɪd fˈoːɹɾi fˈaɪv mˈɪliən jˈɪɹz ɐɡˈoʊ, ɔːlðˈoʊ ɪɾ ɪz pˈɑːsᵻbəl ðæt nˌaɪɐsɐsˈɔːɹəs ɪz ɐ dˈaɪnəsˌɔːɹ ʌvðə sˈeɪm ˈeɪdʒ, pˈʊʃɪŋ ðɪ ˈɔːɹɪdʒˌɪnz ʌvðə ɡɹˈuːps bˈæk fˈɜːðɚ.
The oldest known dinosauromorph is Asilisaurus, a silesaurid which may have lived as early as the Anisian age of the middle Triassic period, about 245 million years ago, although it is possible that Nyasasaurus is a dinosaur of the same age, pushing the origins of the groups back further.