ðə pˈeɪlɪˌoʊtˈɛθiz ɔːɹ pˈæliːˌoʊtˈɛθiz ˈoʊʃən wʌz ɐn ˈoʊʃən loʊkˈeɪɾᵻd ɐlˈɔŋ ðə nˈɔːɹðɚn mˈɑːɹdʒɪn ʌvðə pˌeɪliːoʊkˈɑːntɪnənt ɡəndwˈɑːnə ðæt stˈɑːɹɾᵻd tʊ ˈoʊpən dˈʊɹɹɪŋ ðə mˈɪdəl kˈæmbɹiən, ɡɹˈuː θɹuːˈaʊt ðə pˌeɪliːoʊzˈoʊɪk, ænd fˈaɪnəli klˈoʊzd dˈʊɹɹɪŋ ðə lˈeɪt tɹaɪˈæsɪk; ɛɡzˈɪstɪŋ fɔːɹ ɐbˌaʊt fˈoːɹhˈʌndɹɪd mˈɪliən jˈɪɹz.
The Paleo-Tethys or Palaeo-Tethys Ocean was an ocean located along the northern margin of the paleocontinent Gondwana that started to open during the Middle Cambrian, grew throughout the Paleozoic, and finally closed during the Late Triassic; existing for about 400 million years.