Potoroidae Gray 1821

Potoroidae Gray, 1821

CONTENTS: Aepyprymnus, Bettongia,? Bettongia † moyesi, Caloprymnus, and Potorous (fig. 54).

STEM AGE: 19.3 Mya (95% HPD: 18.0–22.0 Mya).

CROWN AGE: 15.7 Mya (95% HPD: 11.7–22.0 Mya).

UNAMBIGUOUS CRANIODENTAL SYNAPOMORPHIES: None.

COMMENTS: Monophyly of Potoroidae is strongly supported in our molecular (figs. 27–29) and total-evidence (figs. 32, 33) analyses, as it has been in other recent molecular and total-evidence studies (Meredith et al., 2009a, 2009b, 2009 c, 2011; Llamas et al., 2015; Mitchell et al., 2014; May-Collado et al., 2015; Duchêne et al., 2018; Cascini et al., 2019; Celik et al., 2019; Álvarez-Carretero et al., 2021). However, morphological studies have failed to consistently support potoroid monophyly (Kear et al., 2007; Kear and Pledge, 2008; Prideaux and Warburton, 2010; Black et al., 2014c; Travouillon et al., 2014b, 2015 a, 2016; Cooke et al., 2015; Butler et al., 2016, 2018; Cascini et al., 2019), and our craniodental analyses similarly did not recover a monophyletic Potoroidae (figs. 30, 31). Perhaps unsurprisingly, no craniodental feature optimizes as an unambiguous synapomorphy of Potoroidae in our dated total-evidence analysis. However, one highly homoplastic dental feature optimizes as a potoroid synapomorphy under Delayed Transformation: m3 hypoconid lingual to salient protoconid (char. 173: 0→1; ci = 0.045).

As discussed (see Macropodidae + Potoridae above), at least one putative potoroid— † Gumardee —is known from late Oligocene (Faunal Zone A) sites at Riversleigh World Heritage Area (Flannery et al., 1983; Travouillon et al., 2016) and possibly also from the late Oligocene Namba Formation (Flannery and Rich, 1986). † Gumardee (not included in our analyses due to its fragmentary preservation) has been recovered as a stem potoroid in one published phylogenetic analysis (Travouillon et al., 2016), although not in others (Butler et al., 2016, 2018; Travouillon et al., 2022). Thus, † Gumardee, together with various “bulungamayines” († Bulungamaya, † Cookeroo, † Ganguroo and † Wabularoo; at least some of which are probably stem macropodids) from Riversleigh Faunal Zone A, and possible additional potoroid material from the Namba Formation (Flannery and Rich, 1986), suggest a late Oligocene split between Macropodidae and Potoroidae. However, we recovered a somewhat younger (early Miocene estimate) for this split in our analyses (see Macropodidae + Potoroidae above), and even if † Gumardee is a stem potoroid, it is not informative about the timing of divergences within crown-clade Potoroidae. At present, the oldest known crown-clade potoroid is probably † Milliyowi bunganditj from the early Pliocene (~4.46 Mya) Hamilton Local Fauna in Victoria (Flannery et al., 1992; Turnbull et al., 2003), which has not been included in the current analysis. Prideaux (1999) concluded that † Milliyowi is more closely related to Aepyprymnus than to any other extant potoroid genus, although this was not tested using a formal phylogenetic analysis. 37 Nevertheless, this is compatible with our estimated divergence dates, which suggest that crown-clade Potoroidae began to diversify during the middle to late Miocene.

Our undated (fig. 32) and dated (fig. 33) totalevidence analyses disagree with regard to the affinities of the only fossil potoroid that we included, the middle Miocene? Bettongia † moyesi (described by Flannery and Archer, 1987b): this taxon was found to be sister to Aepyprymnus + Bettongia in our undated analysis, but it falls outside the potoroid crown clade in our dated analysis. Again, this may be the result of our use of the Fossilized Birth Death model in our dated analysis, as this will tend to reconstruct fossil terminals as originating deeper in the tree (see Dated Total-Evidence Analysis in the Discussion section for more detail). However, as already discussed, we prefer the results of our dated analysis regarding relationships within Macropodiformes (based on their greater congruence with other recent studies of macropodiform systematics), so we tentatively recognize? Bettongia † moyesi as a stem potoroid, as also found by Travouillon et al. (2016). As noted by Flannery and Archer (1987b) in their original description,? Bettongia † moyesi closely resembles living Bettongia species (particularly B. lesueur); if this fossil is, indeed, a stem potoroid, then it seems likely that a Bettongia -like morphology may have been ancestral for crown potoroids.