Aetiocetus

Deméré, Thomas A. & Berta, Annalisa, 2008, Skull anatomy of the Oligocene toothed mysticete Aetioceus weltoni (Mammalia; Cetacea): implications for mysticete evolution and functional anatomy, Zoological Journal of the Linnean Society 154 (2), pp. 308-352 : 344

AETIOCETUS

This clade is diagnosed by two unequivocal synapomorphies: anterior and posterior denticles on posterior upper teeth three or fewer, small and simple (23) and anterior and postcanine teeth weakly heterodont (32; transformation from 1 to 2). An additional four characters are potentially diagnostic of this clade: triangular anterior extension of parietal–frontal suture (4), vertical enamel ridges only on lingual surface of postcanine teeth (22; reversal from 1 to 0), teeth with wide diastemata (24; reversal from 1 to 0) and rostral width at antorbital notch (base) relative to occipital condyle width> 170% (40). This clade is not well supported (bootstrap value 58%). Aetiocetus cotylalveus is identified as the most basal Aetiocetus species and is diagnosed by a single equivocal character: supraorbital process of frontal with deeply concave orbital rim (6). The later diverging species of Aetiocetus ( A. weltoni + A. polydentatus ) are diagnosed by two equivocal synapomorphies: intertemporal region narrow (8; reversal from 1 to 0) and sagittal crest reduced (9). Aetiocetus weltoni is diagnosed by two equivocal characters: deeply concave orbital rim (6) and posteriormost edge of ascending process of maxilla terminates at the posterior border of the supraorbital process of frontal (7; transformation from 0 to 2). Aetiocetus polydentatus is diagnosed by four equivocal characters: broad nasals (5; transformation from 1 to 2), a high tooth count (21; transformation from 1 to 2), lambdoidal crests overhanging temporal wall (34) and posterior extension of premaxilla posterior to posterior extremity of maxilla (38; transformation from 2 to 1).