New specimens of ektopodontids (Marsupialia: Ektopodontidae) from South Australia

Abstract

Knowledge about the extinct phalangeroid family Ektopodontidae is increased by the discovery of new material from several localities. Previously unknown teeth of Chunia illuminata and Ektopodon stirtoni are described respectively from White Sands Basin and Mammalon Hill, Lake Palankarinna, Lake Eyre Basin, South Australia, with M 1 being recorded for the first time for any species of Chunia., and a full maxilla of Ektopodon stirtoni showing the positional relationship between P3 and M1 for the first time; this is even more extreme than the arrangement postulated previously. Another species Ektopodon litolophus has been described on the basis of an M 1 found at the Leaf Locality, Lake Ngapakaldi, Lake Eyre Basin. Material from Lake Tarkarooloo, referred to Ektopodon stirtoni, is redescribed as a new species Ektopodon tommosi. Comparisons of M 1 of Chunia and Ektopodon species now allow evolutionary trends, such as increasing number of cusps on the molar lophs, and simplification of the cusps, to be discerned.

A new ektopodontid possum (Diprotodontia, Ektopodontidae) from the Oligocene of central Australia, and its implications for phalangeroid interrelationships

“…Similarly, in C. pledgei , the wide m1 with sub-pyramidal rather than anteroposteriorly oriented cuspids on the protolophid are interpreted to reflect a functional division along the molar row, performing an initial puncture-crushing phase during mastication. We consider this to be generally congruent with the idea (Pledge, 1986, 1991) that ektopodontids may have occupied a granivorous and/or frugivorous niche.…”

“…The structures on the m1 trigonid of ektopodontid species have ambiguous homology to those in other phalangeroids. Previous authors have regarded, on the basis of their relative placement: the buccal- and lingual-most cuspids on m1 as the protoconid and metaconid, respectively; the anterolingual cuspid as a parastylid; and the cingulid spanning the anterior margin to be a precingulid (e.g., Pledge, 1986; Rich, 1986; Woodburne & Clemens, 1986a). We consider it more parsimonious that the buccal-most cuspid is instead a protostylid because: (1) the protoconid in other basal phalangeroids is more lingually positioned, and (2) the structure does not link caudally to the remnant lingual kink to the cristid obliqua in the new ektopodontid taxon described below.…”

“…The Ektopodontidae are an extinct family of enigmatic, phalangeroid possums known from the upper Oligocene through Lower Pleistocene of mainland Australia (e.g., Stirton et al, 1967;Rich, 1986;Woodburne & Clemens, 1986a;Pledge, 2016). Ektopodontids are characterized by a highly complex, serrated, lophodont dentition, a short face, and large anteriorly oriented orbits (Pledge, 1982(Pledge, , 1991(Pledge, , 2016. The family comprises three genera: Ektopodon Stirton, Tedford and Woodburne, 1967;Chunia Woodburne and Clemens, 1986a;and Darcius Rich, 1986 (Table 1: for review see Pledge, 2016).…”

“…Ektopodontids are characterized by a highly complex, serrated, lophodont dentition, a short face, and large anteriorly oriented orbits (Pledge, 1982(Pledge, , 1991(Pledge, , 2016. The family comprises three genera: Ektopodon Stirton, Tedford and Woodburne, 1967;Chunia Woodburne and Clemens, 1986a;and Darcius Rich, 1986 (Table 1: for review see Pledge, 2016). Each genus is characterized by a distinct molar morphology (Stirton et al, 1967;Rich, 1986;Woodburne & Clemens, 1986b).…”

An exceptional partial skeleton of a new basal raptor (Aves: Accipitridae) from the late Oligocene Namba formation, South Australia

“…The accepted age of the Namba and Etadunna Formations has varied (see Pledge 2016). The Etadunna Formation, and therefore by proxy the Namba Formation, was initially considered to be of Oligocene age when it was first identified (Stirton et al 1961).…”