Vombatidae Burnett, 1830

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 : 232-234

Vombatidae Burnett, 1830

CONTENTS: Lasiorhinus , Vombatus (fig. 45), and † Warendja .

STEM AGE: 22.3 Mya (95% HPD: 17.0–27.9 Mya).

CROWN AGE: 11.4 Mya (95% HPD: 3.7–19.1 Mya).

UNAMBIGUOUS CRANIODENTAL SYNAPOMORPHIES: Masseteric process absent (char. 6: 1→0; ci = 0.125); hypotympanic sinus floor formed by squmosal only (char. 56: 0→1; ci = 0.667); postglenoid process of squamosal absent (char. 75: 0→1; ci = 0.200); P3 open-rooted (char. 123: 1→3; ci = 0.385); and molars with open roots, the crowns growing throughout adulthood (char. 128: 0→1; ci = 1.000).

COMMENTS: All our morphological, molecular, and total-evidence analyses recover monophyly of Vombatidae ( figs. 27–33 ). We have included only hypselodont vombatids among our terminals, and hence the presence of open-rooted P3 and open-rooted molars optimize as unambiguous synapomorphies for the family; however, putative vombatids with rooted P3 and rooted molars are known ( Stirton et al., 1967b; Murray, 1998; Brewer, 2008; Brewer et al., 2008, 2015, 2018), so the inclusion of such plesiomorphic taxa in future analyses may erode dental character support for the family. The other two unambiguous craniodental synapomorphies identified here are in the glenoid region (namely absence of a masseteric process and absence of a postglenoid process of the squamosal) and are presumably correlated with the unusual masticatory pattern of hypselodont vombatids, in which jaw movement during the power stroke of mastication is primarily or exclusively transverse ( Ferreira et al., 1989; Murray, 1998; Crompton et al., 2008; Brewer et al., 2015). The oldest vombatids known from dental material (the early Miocene † Nimbavombatus and † Rhizophascolonus ; Stirton et al., 1967b; Murray, 1998; Brewer et al., 2008, 2015, 2018) are not hypselodont, and they appear to have had an orthal component to their power stroke; however, the morphology of the glenoid region of these taxa, which might be expected to be less specialized than those of hypselodont vombatids, is currently unknown.

Our estimate for the divergence between † Warendja and extant vombatids ( Vombatus and Lasiorhinus ) is poorly constrained, with the 95% HPD extending into the Pliocene; this raises the possibility that the late Miocene † Warendja encorensis may not belong to this genus (see Brewer et al., 2007, 2018: fig. 19).

Figures

FIG. 27. Fifty-percent majority rule consensus of post-burn-in trees that results from Bayesian analysis of our nuclear sequence-only dataset. Black dots at nodes indicate ≥0.95 Bayesian posterior probability (“strong support”); dark gray dots indicate 0.75–0.94 Bayesian posterior probability (“moderate support”); light gray dots indicate 0.50–0.74 Bayesian posterior probability (“weak support”).

FIG. 28. Fifty-percent majority rule consensus of post-burn-in trees that results from undated Bayesian analysis of our mitochondrial sequence-only dataset. Black dots at nodes indicate ≥0.95 Bayesian posterior probability (“strong support”); dark gray dots indicate 0.75–0.94 Bayesian posterior probability (“moderate support”); light gray dots indicate 0.50–0.74 Bayesian posterior probability (“weak support”).

FIG. 29. Fifty-percent majority rule consensus of post-burn-in trees that results from undated Bayesian analysis of our combined nuclear and mitochondrial sequence dataset. Black dots at nodes indicate ≥0.95 Bayesian posterior probability (“strong support”); dark gray dots indicate 0.75–0.94 Bayesian posterior probability (“moderate support”); light gray dots indicate 0.50–0.74 Bayesian posterior probability (“weak support”).

FIG. 30. Strict consensus of 99,999 most parsimonious trees (each of 949 steps, consistency index =0.269, retention index = 0.815) that result from maximum parsimony analysis of our morphological dataset. Black dots at nodes indicate ≥70% bootstrap support (“strong support”); dark gray dots indicate 50%–69% bootstrap support (“moderate support”); light gray dots indicate <50 bootstrap support (“weak support”).

FIG. 31. Fifty-percent majority rule consensus of post-burn-in trees that results from undated Bayesian analysis of our morphological dataset. Black dots at nodes indicate ≥0.95 Bayesian posterior probability (“strong support”); dark gray dots indicate 0.75–0.94 Bayesian posterior probability (“moderate support”); light gray dots indicate 0.50–0.74 Bayesian posterior probability (“weak support”).

FIG. 32. Fifty-percent majority rule consensus of post-burn-in trees that results from undated Bayesian analysis of our total evidence dataset. Black dots at nodes indicate ≥0.95 Bayesian posterior probability (“strong support”); dark gray dots indicate 0.75–0.94 Bayesian posterior probability (“moderate support”); light gray dots indicate 0.50–0.74 Bayesian posterior probability (“weak support”).