Vombatiformes Woodburne, 1984

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 : 227-228

Vombatiformes Woodburne, 1984

CONTENTS: †Diprotodontoidea, † Ilariidae , † Muramura , † Namilamadeta , Phascolarctidae , and Vombatidae .

STEM AGE: 39.8 Mya (95% HPD: 35.5–45.2 Mya).

CROWN AGE: 32.4 Mya (95% HPD: 29.1–36.4 Mya).

UNAMBIGUOUS CRANIODENTAL SYNAPOMORPHIES: Lacrimal exposure with one or more distinct tubercles (char. 8: 0→1; ci = 0.118); paroccipital process is a large erect process usually directed ventrally (char. 93: 1→2; ci = 0.100); P1 absent (char. 114: 0→1; ci = 0.200); P2 absent (char. 116: 0→1; ci = 0.333); distinct posterolingual cusp on semi- or fully sectorial P3 present (char. 125: 0→1; ci = 0.250); second lower premolar absent (char. 154: 0→1; ci = 1.000); entostylid labial to the entoconid present and cusplike (char. 174: 0→1; ci = 0.333).

COMMENTS: Beck et al. (2020: table 1 ) defined Vombatiformes as the most inclusive clade including Vombatus ursinus and Phascolarctos cinereus but not Phalanger orientalis . The family † Thylacoleonidae has usually been considered to be a member of Vombatiformes (e.g., Archer, 1984c; Aplin and Archer, 1987; Aplin, 1987; Marshall et al., 1990; Munson, 1992; Szalay, 1994; Archer and Hand, 2006; Gillespie, 2007; Black et al., 2012a, 2012b; but see Murray et al., 1987, for an alternative view), within which it is usually placed closer to Vombatus than to Phascolarctos —in other words, as a member of Vombatomorphia sensu Beck et al. (2020; see below). However, as noted above, † Thylacoleonidae was placed as the sister to all other vombatiforms (i.e., outside Vombatomorphia) in our undated total-evidence analysis (fig. 32; a relationship also found by Gillespie et al., 2016; Beck et al., 2020), and it was recovered in a trichotomy at the base of Diprotodontia together with Vombatiformes and Phalangerida in our dated total-evidence analysis ( fig. 33). Based on these results, we suggest that † Thylacoleonidae is best considered as Diprotodontia incertae sedis. Thus, in our dated total-evidence analysis, Vombatiformes sensu Beck et al. (2020) is restricted to †Diprotodontoidea, † Ilaria , Phascolarctidae , Vombatidae , † Muramura , and † Namilimadeta. Members of the families † Maradidae , † Palorchestidae , and † Mukupirnidae have not been included here, but have been recovered within Vombatiformes in recent phylogenetic analyses ( Black et al., 2012a; Brewer et al., 2015; Gillespie et al., 2016; Beck et al., 2020). Among the unambiguous synapomorphies of this restricted Vombatiformes are loss of P1, P2, and p2 (see above); all these teeth are retained in plesiomorphic thylacoleonids ( Gillespie et al., 2016; Beck et al., 2020).

The oldest known definitive vombatiforms are from the late Oligocene of Australia ( Archer et al., 1999; Long et al., 2002; Archer and Hand, 2006; Black et al., 2012b). This is congruent with our estimated divergence dates, which suggest that the initial diversification of vombatiforms took place during the late Eocene or early Oligocene.