Macropodidae Gray, 1821

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 : 253-255

Macropodidae Gray, 1821

CONTENTS: † Bohra , Dendrolagus , Dorcopsis , Dorcopsulus , † Ganguroo , † Hadronomas , Lagorchestes , Lagostrophus (fig. 53), Macropus , Notamacropus , Onychogalea , Osphranter , Petrogale , † Rhizosthenurus , Setonix , Thylogale , and Wallabia .

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

CROWN AGE: 18.2 Mya (95% HPD: 17.8–19.7 Mya).

UNAMBIGUOUS CRANIODENTAL SYNAPOMORPHIES: Parietal and alisphenoid in contact on lateral aspect of braincase (char. 26: 1→0; ci = 0.071); principal labial and lingual cusps of upper molars connected by well-developed lophs (char. 144: 1→2; ci = 0.200); midpoints of protoloph and metaloph connected by a “midlink” (char. 145: 0→1; ci = 0.500); and entocristid indistinct or absent (char. 176: 0→1; ci = 0.077).

COMMENTS: As already discussed, monophyly of Macropodidae (sensu Kear and Cooke, 2001) was not supported in our undated total-evidence analysis (fig. 32) due to the surprising (and almost certainly erroneous) position of the balbarids † Balbaroo and † Ganawamaya in a clade with the macropodids Dorcopsis , Dorcopsulus , † Ganguroo , † Hadronomas , and † Rhizosthenurus . The following discussion therefore applies to the clade recovered by our dated total-evidence analysis ( fig. 33), in which balbarids were constrained to fall outside Macropodidae + Potoroidae , in agreement with all recent published phylogenetic analyses focused on macropodiform relationships ( Kear and Cooke, 2001; Cooke, 2006; Kear et al., 2007; Kear and Pledge, 2008; Bates et al., 2014; Black et al., 2014c; Travouillon et al., 2014b, 2015 a, 2016, 2022; Cooke et al., 2015; Butler et al., 2016, 2018; den Boer and Kear, 2018). Contact of the parietal and alisphenoid on the lateral aspect of the braincase, which optimizes as an unambiguous synapomorphy of Macropodidae in our dated total-evidence analysis, is a consistent feature among macropodids and its relevance for macropodiform systematics has often been discussed ( Pearson, 1950; Archer, 1984c; Case, 1984; Flannery et al., 1984; Flannery and Archer, 1987b, 1987c; Flannery, 1989; Burk et al., 1998; Cooke, 1999, 2000; Kear and Cooke, 2001; Kear et al., 2007; Prideaux and Warburton, 2010). However, alisphenoid-parietal versus frontal-squamosal contact is highly homoplastic within Marsupialia as a whole (see char. 26) with a very low consistency index (0.071, see above), and the presence of alisphenoid-parietal contact in the fossil hypsiprymnodontid Hypsiprymnodon † bartholomaii indicates that this character is also homoplastic within Macropodiformes ( Flannery and Archer, 1987b, 1987c; Flannery, 1989; Burk et al., 1998; Cooke, 1999, 2000; Kear et al., 2007). Presence of well-developed lophs connecting the principal labial and lingual cusps of the upper molars also optimizes as a synapomorphy of Macropodidae , as does presence of a midlink, but this may be influenced by our decision to enforce monophyly of Macropodidae + Potoroidae to the exclusion of Balbaridae (which are also fully lophodont and have a midlink; see chars. 144, 145 and “† Balbaridae ” above). Nevertheless, Cooke (1997a, 1997 b, 1997c) presented evidence that macropodids and balbarids did indeed independently acquire fully lophodont molars.

Our dated analysis placed the fossil terminals † Ganguroo , † Hadronomas , and † Rhizosthenurus within total-clade Macropodidae but outside the crown clade (= Lagostrophus + Macropodinae). Of these, † Hadronomas and † Rhizosthenurus are currently recognized as plesiomorphic members of the extinct macropodid subfamily † Sthenurinae ( Murray, 1991, 1995; Kear and Cooke, 2001; Kear, 2002; Kirkham, 2004; Prideaux, 2004; Prideaux and Warburton, 2010), which achieved considerable diversity during the Plio-Pleistocene ( Long et al., 2002; Prideaux, 2004; Prideaux and Warburton, 2010; Black et al., 2012b; Couzens and Prideaux, 2018). The placement of † Hadronomas and † Rhizosthenurus in a clade that falls outside crown-clade Macropodidae here is congruent with their membership in † Sthenurinae .

Within the macropodid crown clade, we found Lagostrophus (the only extant lagostrophine) to be sister to our remaining terminals (which collectively comprise Macropodinae). By contrast, other studies have placed Lagostrophus in a clade with sthenurines ( Flannery, 1983, 1989; Llamas et al., 2015: fig. 1c; Cascini et al., 2019) or outside †Sthenurine + Macropodinae ( Prideaux and Warburton, 2010; Prideaux and Tedford, 2012; Llamas et al., 2015: fig. 1a). The topology found here may be the result of our use of the Fossilized Birth Death model (see Dated Total-Evidence Analysis in the Discussion section for more detail), with † Rhizosthenurus (late Miocene) and † Hadronomas (late Miocene or earliest Pliocene) recovered as branching deeper within Macropodidae than the extant Lagostrophus . This hypothesis could be tested by inclusion of younger sthenurines or older lagostrophines; however, whereas well-preserved remains of sthenurines are known from the Pleistocene ( Prideaux, 2004), the oldest known lagostrophine (the Pliocene † Tjukuru wellsi ) is known only from a single partial lower jaw ( Prideaux and Tedford, 2012).

As discussed above (see Macropodidae + Potoroidae ), the oldest known macropodids appear to be the “bulungamayines” † Bulungamaya , † Cookeroo , † Ganguroo , and † Wabularoo , which are known from the late Oligocene (Faunal Zone A) sites at Riversleigh World Heritage Area ( Cooke, 1997 b, 1997 c, 2006; Travouillon et al., 2014b; Butler et al., 2016, 2017). However, these taxa consistently fall outside crown-clade Macropodidae (as found for † Ganguroo here) in published analyses ( Kear et al., 2001a, 2001 b, 2007; Kear and Cooke, 2001; Kear, 2002; Kear and Pledge, 2008; Prideaux and Warburton, 2010; Prideaux and Tedford, 2012; Black et al., 2014c; Phillips, 2015; Travouillon et al., 2014b, 2015 a, 2016; Butler et al., 2016, 2018; Cascini et al., 2019). Thus, they do not provide insight on the timing of divergences within the macropodid crown clade ( Phillips, 2015). We estimate the split between Lagostrophinae and Macropodinae to have occurred during the middle or late Miocene, with Macropodinae beginning to radiate during the late Miocene. These estimated dates are congruent with the known fossil record ( Couzens and Prideaux, 2018): the oldest crownclade macropodid currently known is probably the fossil dorcopsin macropodine † Dorcopsoides fossilis from the late Miocene Alcoota Local Fauna in the Northern Territory ( Woodburne, 1967; Prideaux and Warburton, 2010; Butler et al., 2018). They are also broadly similar (but overall somewhat younger) to dates from recent molecular- and total-evidence clock analyses ( Meredith et al., 2009a, 2009b; Llamas et al., 2015; Mitchell et al., 2014; Dodt et al., 2017; Nilsson et al., 2018; Cascini et al., 2019; Celik et al., 2019; Álvarez-Carretero et al., 2021).