Yarala burchfieldi, a plesiomorphic bandicoot (Marsupialia, Peramelemorphia) from Oligo-Miocene deposits of Riversleigh, northwestern Queensland

Abstract

Yarala burchfieldi n. gen. and sp. is described from Oligo-Miocene deposits of Riversleigh Station, northwestern Queensland. Although the smallest and most plesiomorphic bandicoot known, it shares unique synapomorphies with other peramelemorphs, such as the posteriorly orientated preparacrista on M2, posterolingual location of the hypoconulids, and the buccal position of the centrocrista. However, Y. burchfieldi lacks synapomorphies that would unambiguously allow it to be placed in any of the modern families as currently understood. In its plesiomorphic features, Y. burchfieldi provides a structural link between peramelemorphs and dasyuromorphs and appears to be a descendant of an annectant group that separated long prior to the origin of “typical” bandicoots. This species is present in many sites within the Riversleigh area. It possibly filled an insectivorous-carnivorous niche presently occupied by small dasyurids that are relatively more abundant today than they were when the Riversleigh deposits accumulated.

Sexually Dimorphic Bandicoots (Marsupialia: Peramelemorphia) From the Oligo-Miocene of Australia, First Cranial Ontogeny for Fossil Bandicoots and New Species Descriptions

“…Peramelemorphian systematics follows Muirhead (1994Muirhead ( , 2000, Muirhead and Filan (1995), Travouillon et al (2010), and Westerman et al (2012). Cranial and dental terminology follows Archer (1976), Muirhead (1994Muirhead ( , 2000, Muirhead and Filan (1995), Turnbull et al (2003), Voss and Jansa (2003), Wible (2003), , and Travouillon et al (2010). Molar and dP3 loci homology follows Luckett (1993).…”

“…If this is the case, squamosal/frontal contact would be a synapomorphy for all modern peramelemorphians and a feature that rationalizes the monophyly of a clade that includes Madju with these modern taxa to the exclusion of Yarala, Galadi, and Bulungu. It is noteworthy to mention that the interruption of the upper molar centrocrista used to be a defining character for peramelemorphians but a remnant of a connected centrocrista is present in Peroryctes broadbenti (Aplin et al 2010) and variations in the connection of the centrocrista exist in various fossil taxa (e.g., Muirhead and Filan 1995;Gurovich et al 2013;Travouillon et al 2010Travouillon et al , 2013aTravouillon et al , 2013b.…”

Phylogenetic Relationships and Classification of Didelphid Marsupials, an Extant Radiation of New World Metatherian Mammals

“…The upper molars of Recent peramelemorphians differ from those of didelphids in several respects, most notably by having a discontinuous centrocrista: instead of forming a '-shaped (labially inflected) crest with an apex that is lingual to the stylar shelf, the postparacrista and the premetacrista of modern peramelemorphians terminate on the labial margin of the tooth, where they are separated by a small gap (Muirhead and Filan [1995] referred to this trait as the result of the centrocrista ''breaching'' the ectoloph). Additionally, all modern peramelemophians have a large posterolingual cusp on M1-M3; in most genera (e.g., Echymipera, Perameles) this is a hypertrophied metaconule, but in Macrotis it is the metacone (Archer, 1976b).…”

A revised faunal list and geological setting for Bullock Creek, a Camfieldian site from the Northern Territory of Australia

“…While a complete centrocrista is a character shared between yaraloid bandicoots and dasyuromorphs, in yaralids, a smaller angle is formed between the postparacrista and the premetacrista, such as is observed here. The centrocrista is also more buccally positioned than in dasyuromorphs (Muirhead and Filan, 1995). This tooth, although quite worn, appears most similar to Yarala kida, allowing for the removal of stylar cusp B through wear.…”

“…The lower teeth of peramelemorphians are not easily assigned, particularly where isolated teeth are concerned. This makes the identifications of those teeth above as yaraloid bandicoot, on the basis of their similarities to Yarala kida from Kangaroo Well (Schwartz, 2006a) and Y. burchfieldi from Riversleigh (Muirhead and Filan, 1995), less certain than the identification that is based on the upper molar. Gurovich et al (2014) Determination.…”