Badjcinus turnbulli Muirhead & Wroe 1998

SPECIES SCORED: † Badjcinus turnbulli (type and only described species).

GEOLOGICAL PROVENANCE OF SCORED SPECIMENS: White Hunter Site (Riversleigh Faunal Zone A), Riversleigh World Heritage Area, Queensland, Australia.

AGE OF SCORED SPECIMENS: Riversleigh Faunal Zone A is currently interpreted to be late Oligocene based on biostratigraphy (Archer et al., 1989, 1994, 1995, 1997, 2006; Creaser, 1997; Myers and Archer, 1997; Travouillon et al., 2006; Black, 2010; Black et al., 2012b, 2013; Woodhead et al., 2014; Arena et al., 2015). Specifically, Myers and Archer (1997) correlated it with the Ngama Local Fauna, which occurs in Zone D of the Etadunna Formation at Mammalon Hill, South Australia, based on the shared presence of the ilariid † Kuterintja ngama. Based on palaeomagnetic data presented by Woodburne et al. (1994), Metzger and Retallack (2010) estimated the Etadunna Formation to span 26.1–23.6 Mya, so a similar age range for Riversleigh Faunal Zone A seems plausible. However, pending the publication of absolute dates, a more conservative approach is to use the entire range of the late Oligocene (Chattian; Cohen et al., 2013 [updated]) for this taxon.

ASSIGNED AGE RANGE: 27.820 –23.030 Mya.

REMARKS: † Badjcinus turnbulli is the oldest fossil dasyuromorphian represented by relatively wellpreserved craniodental material. It is currently known from a single partial cranium that includes a well-preserved auditory region (QM F30408) and additional dental specimens (Muirhead and Wroe, 1998). † Badjcinus turnbulli differs from all other known dasyuromorphians in lacking both a squamosal epitympanic sinus and a distinct rostral tympanic process of the petrosal, although there is some debate as to whether these features are plesiomorphic or apomorphic (Muirhead and Wroe, 1998; Murray and Megirian, 2006a).

Muirhead and Wroe (1998) identified † Badjcinus as a thylacinid, and thylacinid affinities for this taxon have been supported in most phylogenetic analyses (Wroe and Musser, 2001; Murray and Megirian, 2006a; Yates, 2014, 2015b; Archer et al., 2016; Kealy and Beck, 2017; Rovinsky et al., 2019). However, the craniodental analysis of Wroe et al. (2000) placed † Badjcinus closer to Dasyuridae than to Thylacinus, and the dated total evidence analyses of Kealy and Beck (2017) recovered † Badjcinus as sister to all other dasyuromorphians, and hence outside the crown clade (Dasyuroidea sensu Kealy and Beck, 2017: table 1). We therefore follow Kealy and Beck (2017) as classifying † Badjcinus as? Thylacinidae.