Hypsiprymnodontidae Collett, 1887

Beck, Robin M. D., Voss, Robert S. & Jansa, Sharon A., 2022, Craniodental Morphology And Phylogeny Of Marsupials, Bulletin of the American Museum of Natural History 2022 (457), pp. 1-353 : 249-251

Hypsiprymnodontidae Collett, 1887

CONTENTS: Hypsiprymnodon † bartholomaii and H. moschatus (fig. 52).

STEM AGE: 27.7 Mya (95% HPD: 23.6–32.1 Mya).

CROWN AGE: 16.9 Mya (95% HPD: 11.7–22.0 Mya).

UNAMBIGUOUS CRANIODENTAL SYNAPOMORPHIES: Cristid obliqua with strongly developed “buccal kink” (char. 168: 0→1; ci = 0.333).

COMMENTS: Ride (1993) recognized the family Hypsiprymnodontidae as comprising two subfamilies: Hypsiprymnodontinae (for the extant genus Hypsiprymnodon only) and †Propleopinae (for † Ekaltadeta , † Jackmahoneya , and † Propleopus ). This arrangement has been followed by most subsequent authors ( Wroe and Archer, 1995; Kirsch et al., 1997; Ride et al., 1997; Wroe, 1997c; Cooke and Kear, 1999; Kear and Cooke, 2001; Long et al., 2002; Cooke, 2006; Black et al., 2012b; Bates et al., 2014; Jackson and Groves, 2015). However, Wroe et al. (1998) suggested, based on a study of the cranial morphology of † Ekaltadeta , that propleopines might be more closely related to balbarids than to Hypsiprymnodon . Our dated total-evidence analysis failed to support monophyly of Hypsiprymnodontidae sensu Ride (1993) ; instead, Hypsiprymnodon , † Ekaltadeta , † Balbaridae , and Macropodidae + Potoroidae form a polytomy at the base of Macropodiformes. We therefore restrict Hypsiprymnodontidae to Hypsiprymnodon only. We note that, of our macropodiform terminals, † Ekaltadeta is uniquely plesiomorphic in retaining p2 and P2 into adulthood, whereas these teeth are lost in all the others, including balbarids and Hypsiprymnodon ; however, Hypsiprymnodon is unusual among macropodiforms in retaining P2 for a short period after dP3 has been replaced by P3 (see char. 117).

Monophyly of Hypsiprymnodontidae in this restricted sense (comprising just Hypsiprymondon moschatus and H. † bartholomaii ) is unambiguously supported only by the derived presence of a “buccal kink” in the cristid obliqua of the lower molars. However, this feature is also found in phalangerids, as well as in some fossil phalangeroids, Dactylopsila , possibly Burramys , and Pseudochirulus (see char. 168). Although the presence of a buccally kinked cristid obliqua is interpreted as independently derived in Hypsiprymnodon and phalangerids based on our analyses, this interpretation may change if additional fossil phalangeridans (e.g., ektopodontids, miralinids) were to be included in future datasets.

The oldest known hypsiprymnodontid fossils, in our restricted sense of the family, are an undescribed species of Hypsiprymnodon from late Oligocene (Faunal Zone A) sites at Riversleigh World Heritage Area ( Archer et al., 2006; Black et al., 2012b; Butler et al., 2017) and “Hypsiprymnodontinae indet.” from the late Oligocene Namba Formation ( Flannery and Rich, 1986). Both records are congruent with our Oligocene estimate for the divergence of Hypsiprymnodon from other macropodoids. However, the presence of probable stem macropodids in the late Oligocene (e.g., Bulungamaya , Cookeroo , and Ngamaroo ; Prideaux and Warburton, 2010; Phillips, 2015; Butler et al., 2016, 2017) suggests that the divergence between Macropodidae and Potoroidae had already occurred by this time, in which case our estimate for the divergence between Hypsiprymnodontidae and Macropodidae + Potoroidae , which must have been earlier, would appear to be too young.