SPECIES SCORED: † Mayulestes ferox (type and only described species).

GEOLOGICAL PROVENANCE OF SCORED SPECIMENS: Tiupampa, Santa Lucía Formation, Bolivia.

AGE OF SCORED SPECIMENS: Early or middle Paleocene (see † Pucadelphys above).

ASSIGNED AGE RANGE: 65.118 –59.200 Mya.

REMARKS: † Mayulestes ferox was described by Muizon (1994; 1998) as the earliest and most plesiomorphic known member of the order † Sparassodonta (= “Borhyaenoidea” in Muizon’s [1994, 1998] usage), an exclusively South American clade of carnivorously adapted forms that survived until the Pliocene (Argot, 2004; Prevosti and Forasiepi, 2018). A number of phylogenetic analyses have failed to recover † Mayulestes within † Sparassodonta (Rougier et al., 1998, 2004, 2015; Forasiepi, 2009; Engelman and Croft, 2014; Forasiepi et al., 2014a; Suarez et al., 2015; Ni et al., 2016; Wilson et al., 2016; Engelman et al., 2020). However, Muizon et al. (2018) argued strongly in favor of † Mayulestes as a plesiomorphic sparassodont, which they placed together with † Allqokirus (see below) and † Patene in the family † Mayulestidae. We follow Muizon et al. (2018) in considering † Mayulestes to be a member of † Sparassodonta, within the superorder †Pucadelphyda (see † Pucadelphys above).

Like † Pucadelphys (see above), † Mayulestes has been consistently recovered inside Marsupialiformes sensu Beck (2017a; see also Vullo et al., 2009) but outside Marsupialia in published phylogenetic analyses, regardless of whether it has been placed within † Sparassodonta or not (Rougier et al., 1998, 2004, 2015; Luo et al., 2003, 2011; Asher et al., 2004; Ladevèze and Muizon, 2007; Sánchez-Villagra et al., 2007; Beck et al., 2008, 2014; Horovitz et al., 2008, 2009; Forasiepi, 2009; Ladevèze and Muizon, 2010; Luo et al., 2011; Beck, 2012, 2017b; Williamson et al., 2012, 2014; Engelman and Croft, 2014; Forasiepi et al., 2014a; Suarez et al., 2015; Lorente et al., 2016; Ni et al., 2016; Wilson et al., 2016; Carneiro and Oliveira, 2017a, 2017b; Maga and Beck, 2017; Bi et al., 2018; Carneiro et al., 2018; Muizon et al., 2018; Abello and Candela, 2019; Carneiro, 2019; Rangel et al., 2019; Engelman et al., 2020; Ladevèze et al., 2020; Muizon and Ladevèze, 2020; Zimicz and Goin, 2020). This, together with the excellent preservation of the holotype and only known specimen— MNHC 1249, which comprises a nearly complete cranium and associated left and right mandibles (Muizon, 1994, 1998)—renders it a suitable outgroup taxon for our study.