Balbaroo fangaroo, Cooke, 2000

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 : 337-338

† Balbaroo

SPECIES SCORED: † Balbaroo fangaroo .

GEOLOGICAL PROVENANCE OF SCORED SPECIMENS: Riversleigh Faunal zones A and B, Riversleigh World Heritage Area, Queensland, Australia.

AGES OF SCORED SPECIMENS: Riversleigh Faunal zones A and B are interpreted to be late Oligocene and early Miocene, respectively, based on biostratigraphy (see above). In the absence of radiometric dates, we have assumed the entire span of the late Oligocene to the early Miocene (Chattian to Burdigalian; Cohen et al., 2013 [updated]) for this terminal.

ASSIGNED AGE RANGE: 27.820 –15.970 Mya.

REMARKS: Flannery et al. (1983) described † Balbaroo camfieldensis (the type species) from the?middle Miocene Bullock Creek Local Fauna, and † B. gregoriensis from the G Site of Riversleigh Faunal Zone A, and referred them to a new macropodid subfamily, †Balbarinae. Flannery et al. (1983: 295) concluded that “balbarines appear to represent the most primitive macropodids known.” Later, Kear and Cooke (2001) ranked balbarines as a family-level clade based on the work of Cooke (1997a, 1997b, 1997c), which indicated that balbarids evolved fully lophodont molars independently from macropodids. Subsequent phylogenetic analyses have typically recovered † Balbaridae outside a clade that includes the extant macropodoid families Macropodidae and Potoroidae (Kear et al., 2007; Kear and Pledge, 2008; Bates et al., 2014; Black et al., 2014c; Travouillon et al., 2014b, 2015a, 2016; Cooke et al., 2015; Butler et al., 2016, 2018). However, the affinities of balbarids are otherwise somewhat unstable, with different analyses finding a close relationship with † Ekaltadeta and (when included) other propleopines (Kear et al., 2007; Kear and Pledge, 2008; Butler et al., 2016, 2018), with both † Ekaltadeta (and other propleopines, if included) and Hypsiprymnodon (Travouillon et al., 2014b, 2015a; Cooke et al., 2015; den Boer and Kear, 2018: figs. S5, S9-S11), or with neither (Travouillon et al., 2016; den Boer and Kear, 2018: figs. S4, S6, S8). The morphological analysis of Travouillon (2016: fig. 7) and the tip-and-node dated total-evidence analysis of Cascini et al. (2019: fig. 5) differ from other published analyses in finding † Balbaridae to be paraphyletic rather than monophyletic, and, in Cascini et al.’s (2019: fig. 5) analysis only, closer to Macropodidae than to Potoroidae .

Cooke (2000) described relatively complete craniodental material of two individuals of † Balbaroo fangaroo , both of which we examined to score this taxon. One specimen (QM F30456) reveals the presence of hypertrophied upper canines, a surprising morphology apparently convergent on that seen in some extant artiodactyls (e.g., Tragulus and Moschus), in which this feature is sexually dimorphic. The two other species † Balbaroo species described by Flannery et al. (1983) —† B. camfieldensis and † B. gregoriensis —have not been used for scoring purposes here.