Vombatiformes Woodburne 1984
Creators: name: Beck, Robin M. D.
name: Voss, Robert S.
name: Jansa, Sharon A.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Vombatiformes

description: 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.
description: Published as part of Beck, Robin M. D., Voss, Robert S. & Jansa, Sharon A., 2022, Craniodental Morphology And Phylogeny Of Marsupials, pp. 1-353 in Bulletin of the American Museum of Natural History 2022 (457) on pages 227-228, DOI: 10.1206/0003-0090.457.1.1, http://zenodo.org/record/6971356