wˈʌn baɪvˈælv ɡɹˈuːp, ðə ɹˈuːdɪsts, bɪkˌeɪm mˈeɪdʒɚ ɹˈiːfbˈɪldɚz ɪnðə kɹɛtˈeɪʃəs, bˌʌt bɪkˌeɪm ɛkstˈɪŋkt ɪnðə kɹɛtˈeɪʃəs pˌeɪliːoʊdʒˈiːn ɛkstˈɪŋkʃən ᵻvˈɛnt.
One bivalve group, the rudists, became major reef-builders in the Cretaceous, but became extinct in the Cretaceous–Paleogene extinction event.