The highest BS estimate adjusted for body mass were in two extinct marsupial lions, Thylacoleo carnifex (194) and Priscileo roskellyae (196). The lowest was also in a fossil marsupial, Thylacosmilus atrox (41). Among extant carnivorous mammals the highest BFQ was in the Tasmanian devil, Sarcophilus harrisii (181). For placentals, BFQ was greatest in the Pleistocene dire wolf, Canis dirus (163). Another canid, the African hunting dog, Lycaon pictus, had the highest BFQ for living Carnivora (142).
Mean BFQ was higher in marsupials than placentals (158 versus 98), although marsupials do not have larger heads—relationships between head lengths and body masses in dasyuromorphians were similar to those of canids, and thylacoleonids were similar to felids (). However, relative to body mass, CBS was significantly higher in dasyuromorphians than in canids (F1,13=33.51, p<0.01) and significantly higher in thylacoleonids than in cats (F1,11=11.84, p<0.01).
Basal skull length (BSL) plotted against body mass (BoM). Power regressions are shown for felids (black dashed line), canids (grey solid line), dasyuromorphians (grey dashed line), thylacoleonids (black solid line). Symbols as in .
The average BFQ for Felidae (104) was slightly less than in Canidae (110) and dogs had greater head to body size (), but the difference in this instance was not significant. Across all taxa, skull width was a better predictor of CBS
than skull length (r2
=0.92 and 0.78, respectively; Thomason 1991
was considerable for specialist bone-crackers included in our study, the spotted and brown hyaenas (Crocuta crocuta
and Hyaena hyaena
) and the Tasmanian devil (S. harrisii
). However, in the two hyaenids, BFQ at the canine was exceeded by several non-osteophagous carnivorans (; ) and BFQ for the Tasmanian devil was not much above average for dasyuromorphians and less than in two marsupial lions. BFQ at the carnassial teeth followed a similar pattern (Electronic Appendix, section C), an expected result because the position of the carnassial varies little among mammalian predators (Greaves 1983
As an upper restriction on niche, a predator's maximal prey size is an important component of its ecology and is likely to be strongly influenced by its biomechanical limits. Predator body mass has been shown to correlate with maximal prey size in mammals (Meers 2002
). Among extant canids, the four hypercarnivores that often prey on animals larger than themselves, the grey wolf (Canis lupus lupus
), dingo (C. l. dingo
), African hunting dog (L. pictus
) and the dhole (Canis alpinus
), have the highest BFQ (108–142). BFQ was consistently lower in the five more solitary, omnivorous foxes, jackals and coyote characterized by relatively low maximal prey sizes (80–97). Thus, although the ability to bring down large prey in canids is related to cooperative hunting, it is still reflected in a higher BFQ. Within living Felidae, BFQ values were 57 and 75 for the two species that specialize in relatively small prey, while BFQ was 94 or greater for the seven known to take relatively large prey (). BS
adjusted for body mass was also low in bears (44–78), which are restricted to relatively small prey (Meers 2002
). BFQ was higher in extant dasyuromorphian marsupials, but the same trends were evident. The lowest BFQ was in the eastern quoll (Dasyurus viverrinus
), which takes comparatively smaller prey and is less carnivorous than the other marsupials considered (see below). Overall, BFQ was 100 or higher in 15 of the 16 extant placental and marsupial carnivores sampled that take prey larger than their own maximal body masses. In 12 of the 14 extant species where maximal prey size was less than the species' mean body mass, BFQ was less than 100 (). The difference between large and small prey specialists was significant (t
<0.01) and hypercarnivores had significantly higher values for BFQ than more omnivorous species (t
Table 2 Bite force adjusted for body mass allometry (BFQ), maximal prey size and feeding category in 31 extant mammalian carnivores. (RMPS, maximal prey size (1, greater than maximal body mass of predator; 2, less than maximal body mass of predator); FC, feeding (more ...)