ðɪs dʒˈɛnəs ɪz nˈoʊn fɹʌm pˌeɪliːoʊdʒˈiːn fˈɑːsəlz fɹʌm ˈiːəsˌiːn ænd ˈɑːlɪɡˌoʊsiːn stɹˈɑːɾə ʌv nˈɔːɹθ ɐmˈɛɹɪkə, ɪŋklˈuːdɪŋ ðɪ ɐlˈɛnbi fɔːɹmˈeɪʃən ænd ðə flˈɔːɹɪsənt fɔːɹmˈeɪʃən, ænd pˌeɪliːoʊsˈiːn tʊ ˈɑːlɪɡˌoʊsiːn stɹˈɑːɾə ʌv ɹˈʌʃə.
This genus is known from Paleogene fossils from Eocene and Oligocene strata of North America, including the Allenby Formation and the Florissant Formation, and Paleocene to Oligocene strata of Russia.