Phylogenetic analyses published during the 2000s cast doubt on the idea that many traditional metriorhynchid genera formed natural groups (i.e., include all descendants of a common ancestor).
fˌaɪloʊdʒnˈɛɾɪk ˈænɐlˌaɪzᵻz pˈʌblɪʃt dˈʊɹɹɪŋ ðə tˈuː θˈaʊzənd z kˈæst dˈaʊt ɔnðɪ aɪdˈiə ðæt mˈɛni tɹɐdˈɪʃənəl mˈɛtɹɪɹhˌɪntʃɪd dʒˈɛnɚɹə fˈɔːɹmd nˈætʃɚɹəl ɡɹˈuːps ˈaɪ.ˈiː., ɪŋklˈuːd ˈɔːl dᵻsˈɛndənts əvə kˈɑːmən ˈænsɛstɚ.