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The little red kaluta (Dasykaluta rosamondae) is a small, insectivorous-carnivorous dasyurid marsupial found in and spinifex grasslands of northwestern Australia. Kalutas resemble other dasyurids in many aspects of their physiology. Body temperature (T-b; 33.5 degrees C; 1.5 degrees C lower than predicted), wet thermal conductance (1.6 J g(-1) h(-1) degrees C-1; 91% of predicted), and dry thermal conductance (1.22 J g(-1) h(-1) degrees C-1; 55% of predicted) are not significantly different from allometric predictions for marsupials in the thermoneutral zone (26-33 degrees C). A significantly lower-than-expected basal metabolic rate (0.55 ml O-2 g(-1) h(-1); 58% of allometric prediction) and evaporative water loss (1.11 mg g(-1) h(-1); 39% of predicted) can be attributed to the combined effect of low T-b and phylogeny. Physiological adaptation to aridity is further reflected by a substantially smaller body mass (35 g) than predicted by phylogeny (200 g), a thermolabile T-b and use of torpor, which confer significant energy and water savings, and a high point of relative water economy (16.1 degrees C).