Ilaria

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 : 331

† Ilaria

SPECIES SCORED: † Ilaria illumidens (type species), † I. lawsoni .

GEOLOGICAL PROVENANCE OF SCORED SPECIMENS: AMNH site B, Zone B (Pinpa Local Fauna) Namba Formation, Lake Pinpa, South Australia († I. illumidens ); AMNH SIAM locality, unit 6, Zone B (Ditjimanka Local Fauna), Lake Palankarinna, Etadunna Formation, South Australia († I. lawsoni );

AGE OF SCORED SPECIMENS: Based on palaeomagnetic data, Metzger and Retallack (2010) estimated the Etadunna Formation to span 26.1– 23.6 Mya. Zone A of the Etadunna Formation and the Pinpa Local Fauna of the Namba Formation appear to be stratigraphic equivalents (Woodburne et al., 1994). However, in the absence of radiometric dates, we have assumed the entire span of the late Oligocene (Chattian; Cohen et al., 2013 [updated]) for this terminal.

ASSIGNED AGE RANGE: 27.820 –23.030 Mya.

REMARKS: † Ilaria illumidens is represented by craniodental and associated postcranial elements of several individuals, while the slightly larger † I. lawsoni is known from a single partial right dentary only (Tedford and Woodburne, 1987). Both species are characterized by large size (estimated body mass of † Ilaria illumidens is ~ 215 kg; Beck et al., 2020) and several unusual craniodental features. The upper molars are strongly selenodont, while the lower molars are incipiently lophodont with prominent neomorphic cuspids present; Tedford and Woodburne (1987) identified the “central cuspid” between the metaconid and protoconid, and a second between the hypconid and entoconid, as neomorphic, but could not rule out the possibility that it is in fact the lingual cuspids (the putative “metaconid” and “entoconid”) are the neomorphs (Tedford and Woodburne, 1987: 415), and we have treated the homologies of these structures as unknown in this study. † Ilaria is also unusual in that the mandibular symphysis is fused, a feature otherwise seen only in a few other vombatiforms (see char. 97). Another ilariid, the much smaller (estimated body mass ~ 16 kg; Beck et al., 2020) † Kuterintja ngama , is known from the Ngama Local Fauna (Zone D of the Etadunna Formation; Pledge, 1987b; Woodburne et al., 1994) and the Riversleigh Faunal Zone A White Hunter Site (Myers and Archer, 1997), both of which are late Oligocene (see above); however, † K. ngama specimens is currently represented by fragmentary dental material only, and so has not been included here.