Because of the complexity of the crown, Goin and colleagues identified the tooth as a mammal; although some non-mammalian groups, like crocodylians, may have complex teeth, none approach the level of complexity seen in LACM 149371. They could find no resemblance to australosphenidans including monotremes, metatherians including marsupials, xenarthrans, and some related groups.Goin et al., 2004, p. 151 They did see some general resemblances to the upper premolars of the early South American ungulates, but the cusp arrangement is different from that of any ungulate.Goin et al., 2004, pp. 151–152 There are also some resemblances to the early rodents Ivanantonia from Asia and Nonomys from North America, but Ivanantonia has a central groove and lacks fossae, and Nonomys has a prominent cingulum (shelf) at the edges of the tooth and also lacks the fossae of LACM 149371.Goin et al., 2004, p. 152
