Ngapakaldia

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 : 329

† Ngapakaldia

SPECIES SCORED: † Ngapakaldia tedfordi (type species), † N. bonythoni ; † Ngapakaldia sp.

GEOLOGICAL PROVENANCE OF SCORED SPECIMENS: Ngapakaldi Local Fauna, Etadunna Formation, Lake Ngapakaldi, South Australia, Australia († Ngapakaldia bonythoni , † N. tedfordi , and † Ngapakaldia sp. ); AL Site, D Site, Hiatus, Hiatus South, Jeanette’s Amphitheatre, Lee Sye’s Outlook (LSO), Sticky Beak, Upper Burnt Offering, and White Hunter sites (Riversleigh Faunal Zone A), and Bone Reef, Camel Sputum, Dirk’s Towers, Dunsinane, and Mike’s Potato Patch sites (Riversleigh Faunal Zone B), Riversleigh World Heritage Area, Queensland Australia († N. bonythoni ).

AGES OF SCORED SPECIMENS: Based on palaeomagnetic data, Metzger and Retallack (2010) estimated the Etadunna Formation to span 26.1–23.6 Mya. Riversleigh Faunal zones A and B are interpreted as late Oligocene and early Miocene, respectively, based on biostratigraphy (see above).

ASSIGNED AGE RANGE: 27.820 –15.970 Mya.

REMARKS: In his original description of † Ngapakaldia tedfordi and † N. bonythoni, Stirton (1967) suggested a close relationship between these taxa and † Palorchestes, placing them together in the diprotodontid subfamily †Palorchestinae. More recent studies (e.g., Murray, 1990; Black and Archer, 1997a; Black, 2010) have suggested that † Ngapakaldia is more appropriately placed in the subfamily †Diprotodontinae and that the similarities between † Ngapakaldia and † Palorchestes (now usually placed in a separate family, † Palorchestidae ) are plesiomorphies. Both † N. tedfordi and † N. bonythoni were originally described based on material from the †Ngapakaldi Local Fauna (Faunal Zone C of the Etadunna Formation; Stirton, 1967; Woodburne et al., 1994), but Black (2010) referred additional specimens from Riversleigh Faunal zones A and B to † N. bonythoni . We used Ngapakaldi specimens of † N. tedfordi , and Ngapakaldi and Riversleigh specimens of † N. bonythoni , to score a composite † Ngapakaldia terminal. Rich and Vicker-Rich (1987) listed additional fragmentary specimens of both species from various sites in the Etadunna and Namba formations, but we did not use this material for scoring purposes.