Molar crests and body mass as dietary indicators in marsupials

Abstract

The discovery of ecomorphological relationships in mammals is important not only in its own right, but also for its potential in shedding light on the ecology of extinct and poorly known species. Two such potential relationships are the proposed connection between molar shear crests and body mass to diet. Research on primates suggests that, owing to the digestive challenges of structural carbohydrates (in foliage and insects), folivores and insectivores differ from other species in needing relatively long molar shear crests. These studies also suggest that metabolic constraints force folivores to be consistently larger than insectivores, with 500-700 g being the proposed body mass boundary between the two. This study tests these proposed ecomorphological links in a diverse sample of 64 marsupial species. As predicted, folivores and insectivores have significantly relatively longer molar shear crests than other species. Similarly, folivores are significantly larger than insectivores, as predicted, though the proposed body mass boundary was not supported. These results suggest that shear crest length and body mass are indeed linked to diet in the proposed manner. It may now be possible to use these findings to gain a greater understanding of the feeding behaviours of a variety of extinct marsupials and other therians.

Craniomandibular Variation in Phalangeriform Marsupials: Functional Comparisons with Primates

“…Cartmill related these features to the use of the anterior upper incisors in biting through wood to extract wood-boring insect larvae. Additionally, Hogue (2008) found that marsupial folivores show an increase in the vertical bending strength of the mandibular corpus similar to results predicted from the primate literature, and Kay and Hylander (1978) and Hogue and ZiaShakeri (2010) found that molar morphology in marsupials replicates patterns previously observed in primates with regard to the summed length of molar crests.…”

Chewed out: an experimental link between food material properties and repetitive loading of the masticatory apparatus in mammals

“…One issue not addressed by our study is the potentially important role that dental form plays in chewing investment and cyclical loading. Mammals that masticate tough leaves tend to have long, well-developed molar shearing crests, whereas species that exploit hard fruits and seeds tend to have bunodont teeth with much shorter and blunter crests ( Kay, 1975 ; Kay, 1978 ; Walker & Murray, 1975 ; Sheine & Kay, 1977 ; Sheine & Kay, 1982 ; Strait, 1998 ; Hogue & ZiaShakeri, 2010 ). Because “the working surface of the molars have a strong effect on the physiological rate of breakdown” ( Lucas, 2004 , p. 167), it is likely that variation in molar relief translates into intra- and interspecific disparities in chewing investment for different types of foods.…”

Similar Associations of Tooth Microwear and Morphology Indicate Similar Diet across Marsupial and Placental Mammals

“…The minimum body size for obligate marsupial and placental browsers is ∼500 g [94], [95]. Obligate insectivores require body sizes smaller than the threshold for browsers due to the size and patchiness of their food sources, with the exception of specialists feeding on colonial insects (i.e.…”